CMP Journal 2025-04-29
Statistics
Nature Materials: 1
Nature Nanotechnology: 1
Nature Reviews Materials: 1
Physical Review Letters: 10
Physical Review X: 2
arXiv: 108
Nature Materials
All-electrical perpendicular switching of chiral antiferromagnetic order
Original Paper | Electronic and spintronic devices | 2025-04-28 20:00 EDT
Zhenyi Zheng, Lanxin Jia, Zhizhong Zhang, Qia Shen, Guowei Zhou, Zhiwei Cui, Lizhu Ren, Zhiteng Chen, Nur Fadilah Jamaludin, Tieyang Zhao, Rui Xiao, Qihan Zhang, Yi Du, Liang Liu, Silvija Gradečak, Kostya S. Novoselov, Weisheng Zhao, Xiaohong Xu, Yue Zhang, Jingsheng Chen
Antiferromagnets as active components in devices have been attracting attention due to their negligible stray field and ultrafast magnetic dynamics, which are promising for high-density and fast memory devices. Although the switching of antiferromagnetic (AFM) order by current-induced spin-orbit torque (SOT) has already been realized, field-free SOT-induced bidirectional switching of AFM order in perpendicular geometry has been elusive. Here we experimentally demonstrate field-free perpendicular switching of the magnetic octupole moct in chiral AFM Mn3Sn by combining in-plane and out-of-plane SOTs generated by two-dimensional van der Vaals WTe2. The out-of-plane SOT breaks the in-plane inversion symmetry and leads to deterministic bidirectional switching of moct in polycrystalline Mn3Sn even without a fixed perpendicular moct easy axis. The switching ratio reaches up to 80% compared to 20-30% in polycrystalline Mn3Sn and the critical current density is reduced by an order of magnitude to around 1 MA cm-2. Our work promotes the development of chiral AFM devices toward practical application.
Electronic and spintronic devices, Magnetic properties and materials, Spintronics
Nature Nanotechnology
Nanofabrication of silk microneedles for high-throughput micronutrient delivery and continuous sap monitoring in plants
Original Paper | Materials science | 2025-04-28 20:00 EDT
Yunteng Cao, Doyoon Kim, Sally Shuxian Koh, Zheng Li, Federica Rigoldi, Julia Eva Fortmueller, Kasey Goh, Yilin Zhang, Eugene J. Lim, Hui Sun, Elise Uyehara, Raju Cheerlavancha, Yangyang Han, Rajeev J. Ram, Daisuke Urano, Benedetto Marelli
Biomaterials bridging the biotic-abiotic interface in plants offer the opportunity to precisely deliver agrochemicals and continuously monitor plant health, with the goals of increasing resilience to climate change, enhancing crop production and mitigating environmental impact. In this study we report the manipulation of silk fibroin assembly with inorganics nucleation at their phase front to nanomanufacture porous and hollow microneedles that can be interfaced with plants. Plant growth analysis and quantification of wounding gene expression show a non-significant systemic wounding response to the injection of silk microneedles in tomato plants. Microneedles with a hollow structure enable the systemic delivery of plant micronutrients to treat chlorosis in tomato plants and crop biofortification through transport of human micronutrients injected in the petiole and loaded into tomato fruits. Hollow microneedles also provide access to plant vasculature for sap sampling, enabling continuous monitoring and early detection of phytoaccumulation of environmental contaminants such as cadmium.
Materials science, Nanoscience and technology
Nature Reviews Materials
Designing supramolecular catalytic systems for mammalian synthetic metabolism
Review Paper | Biomimetics | 2025-04-28 20:00 EDT
Jingjing Han, Martin Fussenegger
Synthetic biology aims to use interchangeable and independent components to develop specialized systems within cellular and cell-free environments to reconfigure natural genetic systems and create innovative tools for biomedicine and industry. Supramolecular nanocatalysts, which use various mechanisms to enhance catalytic reactions, are being explored as components of synthetic gene circuits to optimize metabolic pathways. In this Review, we discuss progress in the incorporation of supramolecular nanocatalysts into cellular systems. We focus on their design, the types of interactions that serve to maintain their supramolecular structure and especially their integration into mammalian cells, as exemplified by actual and potential applications for energy production, energy conversion and novel therapeutics. We also discuss the interactions between supramolecular nanocatalysts and cellular components in metabolic processes and the potential of such combined systems to underpin future breakthroughs in biotechnology and medicine.
Biomimetics, Catalysis, Supramolecular chemistry, Synthetic biology
Physical Review Letters
In Situ Measurements of Dark Photon Dark Matter Using Parker Solar Probe: Going beyond the Radio Window
Research article | Extensions of gauge sector | 2025-04-28 06:00 EDT
Haipeng An, Shuailiang Ge, Jia Liu, and Mingzhe Liu
Researchers have turned NASA’s Parker Solar Probe into a dark-matter detector, taking advantage of its close encounters with the Sun to search for dark-photon signals.
Phys. Rev. Lett. 134, 171001 (2025)
Extensions of gauge sector, Particle dark matter, Radio frequency techniques, Radio, microwave, & sub-mm astronomy, Hypothetical gauge bosons
Surface Kinematics and the Canonical Yang-Mills All-Loop Integrand
Research article | Gauge theories | 2025-04-28 06:00 EDT
Nima Arkani-Hamed, Qu Cao (曹趣), Jin Dong (董晋), Carolina Figueiredo, and Song He (何颂)
A formulation of gluon scattering amplitudes in terms of curves on surfaces leads to new recursion relations for loop integrands in the Yang-Mills theory without supersymmetry.
Phys. Rev. Lett. 134, 171601 (2025)
Gauge theories, Quantum field theory, Scattering amplitudes
Precise Predictions for Event Shapes in Diphoton Production at the LHC
Research article | Perturbative QCD | 2025-04-28 06:00 EDT
Federico Buccioni, Xuan Chen, Wei-Jie Feng, Thomas Gehrmann, Alexander Huss, and Matteo Marcoli
Photon pair production is an important benchmark process at the LHC, entering Higgs boson studies and new physics searches. It has been measured to high accuracy, allowing for detailed studies of event shapes in diphoton final states. To enable precision physics with diphoton event shapes, we compute the second-order QCD corrections, $\mathcal{O}({\alpha }_{s}^{3})$, to them and study their phenomenological impact.
Phys. Rev. Lett. 134, 171901 (2025)
Perturbative QCD, Photon production, QCD phenomenology
Ultralow ${Q}_{\beta }$ Value for the Allowed Decay of ${^{110}\mathrm{Ag}}^{m}$ Confirmed via Mass Measurements
Research article | Binding energy & masses | 2025-04-28 06:00 EDT
J. Ruotsalainen, M. Stryjczyk, M. Ramalho, T. Eronen, Z. Ge, A. Kankainen, M. Mougeot, and J. Suhonen
The mass of the electron-antineutrino can be determined in dedicated measurements of the $\beta $ spectral shape near the $\beta $ end point of a ${\beta }^{- }$ transition, with a low $Q$ value enhancing the sensitivity of the measurement. One such low $Q$ value candidate is the transition between the ${6}^{+}$ isomer of $^{110}\mathrm{Ag}$ and the ${5}{2}^{+}$ state in $^{110}\mathrm{Cd}$ (${Q}{\beta ,m}^{\ast}=- 0.12(131)\text{ }\text{ }\mathrm{keV}$). To reduce the uncertainty of the $Q$ value, we have used the phase-imaging ion-cyclotron-resonance technique with the JYFLTRAP double Penning trap and performed a high-precision atomic mass measurement of $^{109}\mathrm{Ag}$ with $^{110}\mathrm{Cd}$ as a reference. Combined with the known spectroscopic data, we obtain a reevaluated value ${Q}{\beta ,m}^{\ast}=405(135)\text{ }\text{ }\mathrm{eV}$ for the $^{110}\mathrm{Ag}({6}{\mathrm{m}}^{+})\rightarrow ^{110}\mathrm{Cd}({5}{2}^{+})$ transition. This represents the lowest ${Q}{\beta }$ value for any allowed transition observed to date. In order to estimate the partial half-life (${t}{1/2}$) and branching ratio (Br) of the transition, nuclear shell model calculations were performed using the $jj45pnb$ Hamiltonian in combination with state-of-the-art atomic calculations. The computed values of ${t}{1/2}=2.2{3}{- 1.28}^{+5.24}\times{}{10}^{7}\text{ }\text{ }\mathrm{years}$ and $\mathrm{Br}=3.0{7}{- 2.15}^{+4.16}\times{}{10}^{- 8}$, along with the thermal-neutron capture on stable $^{109}\mathrm{Ag}$ as a viable production method, make $^{110}{\mathrm{Ag}}^{m}$ a promising candidate for future antineutrino mass measurements.
Phys. Rev. Lett. 134, 172501 (2025)
Binding energy & masses, Isomer decays, 90 ≤ A ≤ 149
Quantum Geometric Kohn-Luttinger Superconductivity
Research article | Superconductivity | 2025-04-28 06:00 EDT
Gal Shavit and Jason Alicea
Coulomb repulsion can, counterintuitively, mediate Cooper pairing via the Kohn-Luttinger mechanism. However, it is commonly believed that observability of the effect requires special circumstances, e.g., vicinity of the Fermi level to Van Hove singularities, significant lattice-induced band distortions, or nontrivial Fermi surface topologies. Here, we establish that quantum geometric properties of the constituent electrons can dramatically promote pairing from repulsion via dependence of screening on the quantum metric. We demonstrate quantum-geometry-enhanced superconductivity in two microscopic models with tunable quantum geometry, highlighting the crucial roles of quantum metric anisotropy and inhomogeneity. Our analysis provides an experimentally accessible figure of merit for the importance of quantum geometry to inducing unconventional superconductivity, indicating its relevance to graphene multilayers.
Phys. Rev. Lett. 134, 176001 (2025)
Superconductivity, Unconventional superconductors, BCS theory
Strongly Hybridized Phonons in One-Dimensional van der Waals Crystals
Research article | Phonons | 2025-04-28 06:00 EDT
Shaoqi Sun, Qingyun Lin, Yihuan Li, Daichi Kozawa, Huizhen Wu, Shigeo Maruyama, Pilkyung Moon, Toshikaze Kariyado, Ryo Kitaura, and Sihan Zhao
The phenomena of pronounced electron-electron and electron-phonon interactions in one-dimensional (1D) systems are ubiquitous, which are well described by frameworks of Luttinger liquid, Peierls instability, and concomitant charge density wave. However, the experimental observation of strongly hybridized phonons in 1D was not demonstrated. Herein we report the first observation of strongly hybridized phonons in 1D condensed matters by using double-walled carbon nanotubes (DWNTs), representative 1D van der Waals crystals, by combining the spectroscopic and microscopic tools as well as the ab initio density functional theory (DFT) calculations. We observe uncharted phonon modes in one commensurate and three incommensurate DWNT crystals, three of which concurrently exhibit strongly reconstructed electronic band structures. Our DFT calculations for the experimentally observed commensurate DWNT (7, 7) @ (12, 12) reveal that this new phonon mode originates from a (nearly) degenerate coupling between two transverse acoustic modes (ZA modes) of constituent inner and outer nanotubes having approximately trigonal and pentagonal rotational symmetry along the nanotube circumferences. Such coupling strongly hybridizes the two phonon modes in different shells and leads to the formation of a unique lattice motion featuring evenly distributed vibrational amplitudes over inner and outer nanotubes, distinct from any known phonon modes in 1D systems. All four DWNTs that exhibit the pronounced new phonon modes show small chiral angle twists, closely matched diameter ratios of $\frac{3}{5}$ and decreased frequencies of new phonon modes with increased diameters, all supporting the uncovered coupling mechanism. Our discovery of strongly hybridized phonons in DWNTs opens new opportunities for engineering phonons and exploring novel phonon-related phenomena in 1D condensed matters.
Phys. Rev. Lett. 134, 176101 (2025)
Phonons, 1-dimensional systems, Nanotubes, Density functional theory, Electron diffraction, Raman spectroscopy, Rayleigh scattering
Site-Selective Polar Compensation of Mott Electrons in a Double-Perovskite Heterointerface
Research article | Heterostructures | 2025-04-28 06:00 EDT
Nandana Bhattacharya, Arpita Sen, Ke Qu, Arijit Sinha, Ranjan Kumar Patel, Siddharth Kumar, Jianwei Zhang, Prithwijit Mandal, Suresh Chandra Joshi, Shashank Kumar Ojha, Jyotirmay Maity, Zhan Zhang, Hua Zhou, Fanny Rodolakis, Padraic Shafer, Christoph Klewe, John William Freeland, Zhenzhong Yang, Umesh Waghmare, and Srimanta Middey
Double-perovskite oxides (DPOs) with two transition metal ions (${A}{2}BB’{\mathrm{O}}{6}$) offer a fascinating platform for exploring exotic physics and practical applications. Studying these DPOs as ultrathin epitaxial films on single crystalline substrates can add another dimension to engineering electronic, magnetic, and topological phenomena. Understanding the consequence of polarity mismatch between the substrate and the DPO would be the first step toward this broad goal. We investigate this by studying the interface between a prototypical insulating DPO ${\mathrm{Nd}}{2}{\mathrm{NiMnO}}{6}$ and a wide band gap insulator ${\mathrm{SrTiO}}_{3}$. The interface is found to be insulating in nature. By combining several experimental techniques and density functional theory, we establish a site-selective charge compensation process that occurs explicitly at the Mn site of the film, leaving the Ni sites inert. We further demonstrate that such surprising selectivity, which cannot be explained by existing mechanisms of polarity compensation, is directly associated with their electronic correlation energy scales. This study establishes the crucial role of Mott physics in polar compensation process and paves the way for designer doping strategies in complex oxides.
Phys. Rev. Lett. 134, 176201 (2025)
Heterostructures, Thin films, Density functional theory, Physical vapor deposition, Scanning transmission electron microscopy, X-ray absorption spectroscopy, X-ray diffraction
Spin-Transfer Torque in Altermagnets with Magnetic Textures
Research article | Domain wall motion | 2025-04-28 06:00 EDT
Hamed Vakili, Edward Schwartz, and Alexey A. Kovalev
We predict the existence of anisotropic spin-transfer torque effect in textured altermagnets. To this end, we generalize the Zhang-Li torque to incorporate the symmetry associated with prototypical $d$-wave altermagnets and identify the spin-splitter adiabatic and nonadiabatic torques. Applying our results to domain wall dynamics induced by spin-transfer torque, we find that, in certain regimes, the spin-splitter adiabatic torque can induce domain wall precession, significantly slowing down domain wall motion. The response of the domain wall also becomes anisotropic, reflecting the $d$-wave symmetry of the altermagnet. Furthermore, we observe that the spin-splitter adiabatic torque modifies skyrmion dynamics, inducing anisotropic skyrmion Hall effect. The above phenomena can serve as a hallmark of altermagnetism in textured magnets, distinguishing it from the behavior of ordinary antiferromagnets.
Phys. Rev. Lett. 134, 176401 (2025)
Domain wall motion, Magnetic texture, Spin current, Altermagnets, Thiele equation
Hybrid-Order Skin Effect from Loss-Induced Nonreciprocity
Research article | Phononic crystals | 2025-04-28 06:00 EDT
Jien Wu, Yejian Hu, Zhaojian He, Ke Deng, Xueqin Huang, Manzhu Ke, Weiyin Deng, Jiuyang Lu, and Zhengyou Liu
Skin effects, the phenomena of the bulk states collapsing toward open boundaries, have mostly been revealed in non-Hermitian systems hosting nonreciprocity. Either the first-order or the higher-order of skin effects have been observed. Here, we report our first discovery of a hybrid-order of skin effects, of which the utilized two-dimensional system exhibits not only the first-order skin modes, but also the second-order skin modes respectively on the edges and the corners, the different type of open boundaries. We propose a universal approach to achieving nonreciprocal couplings by virtue of the loss and bilayer degree of freedom, as the critical role it plays. Our models are implemented in square- and diamond-shaped phononic crystals, and the hybrid order of acoustic skin modes is evidenced in experiment. Our Letter may foster the development of non-Hermitian physics.
Phys. Rev. Lett. 134, 176601 (2025)
Phononic crystals, Topological phases of matter, Acoustic metamaterials, Non-Hermitian systems
Critical Clusters in Liquid Crystals: Fractal Geometry and Conformal Invariance
Research article | Nonequilibrium statistical mechanics | 2025-04-28 06:00 EDT
Renan A. L. Almeida and Jeferson J. Arenzon
During phase ordering, twisted nematic liquid crystals self-generate critical clusters in the percolation universality class.
Phys. Rev. Lett. 134, 178101 (2025)
Nonequilibrium statistical mechanics, Percolation, Liquid crystals, Nematic liquid crystals
Physical Review X
Quantum-Enhanced Sensing of Axion Dark Matter with a Transmon-Based Single Microwave Photon Counter
Research article | Axions | 2025-04-28 06:00 EDT
C. Braggio, L. Balembois, R. Di Vora, Z. Wang, J. Travesedo, L. Pallegoix, G. Carugno, A. Ortolan, G. Ruoso, U. Gambardella, D. D’Agostino, P. Bertet, and E. Flurin
A quantum sensing technique to scan for axion dark matter using superconducting qubits boosts search speed 20-fold by circumventing quantum noise limits. This scalable approach enables dark matter experiments with unprecedented sensitivity.
Phys. Rev. X 15, 021031 (2025)
Axions, Dark matter, Quantum metrology, Superconducting qubits, Precision measurements
Controllable Highly Oriented Skyrmion Track Array in Bulk ${\mathrm{Fe}}{3}{\mathrm{GaTe}}{2}$
Research article | Magnetism | 2025-04-28 06:00 EDT
Yunhao Wang, Shiyu Zhu, Chensong Hua, Guojing Hu, Linxuan Li, Senhao Lv, Jianfeng Guo, Jiawei Hu, Runnong Zhou, Zizhao Gong, Chengmin Shen, Zhihai Cheng, Jinan Shi, Wu Zhou, Haitao Yang, Weichao Yu, Jiang Xiao, and Hong-Jun Gao
Precision control of magnetic fields facilitates the creation of skyrmion track arrays in Fe3GaTe2, paving the way for scalable, ordered skyrmion structures for energy-efficient computing and next-generation data storage.
Phys. Rev. X 15, 021032 (2025)
Magnetism, Skyrmions
arXiv
Threshold Switching in Vertically Aligned MoS${_2}$/SiO${_x}$ Heterostructures based on Silver Ion Migration
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Jimin Lee, Rana Walied Ahmad, Sofía Cruces, Dennis Braun, Lukas Völkel, Ke Ran, Joachim Mayer, Stephan Menzel, Alwin Daus, Max C. Lemme
Threshold switching (TS) is a phenomenon where non-permanent changes in electrical resistance of a two-terminal device can be controlled by modulating the voltage bias. TS based on silver (Ag) conductive filaments has been observed in many materials, including layered two-dimensional (2D) transition metal dichalcogenides (TMDs). 2D TMDs are particularly promising for metal ion movement due to their van der Waals (vdW) gaps between their sheets, facilitating ion migration and filament formation without disturbing covalent chemical bonds. In this work, we demonstrate the heterostructure growth of vertically aligned molybdenum disulfide (VAMoS$ {_2}$ ) with an amorphous silicon oxide (SiO$ {_x}$ ) layer on top after sulfurization. We show that Ag ions migrate through this material stack, enabling TS. Our Ag/SiO$ {_x}$ /VAMoS$ {_2}$ /gold (Au) devices exhibit TS at low voltages of ~0.63 V, with high on-state currents over 200 $ {\mu}$ A and stable switching exceeding 10$ {^4}$ cycles. Moreover, we identify two rate-limiting steps for filament formation through a physics-based dynamical model and simulate the switching kinetics. Our devices show a fast on-switching time of 311 ns and spontaneous relaxation in 233 ns. These findings deepen the understanding of SiOx/MoS$ {_2}$ -based RS devices and demonstrate the promise for applications in emerging memories and neuromorphic computing systems.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
39 pages
Cracking in polymer substrates for flexible devices and its mitigation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Anush Ranka, Madhuja Layek, Sayaka Kochiyama, Cristina Lopez-Pernia, Alicia M. Chandler, Conrad A. Kocoj, Erica Magliano, Aldo Di Carlo, Francesca Brunetti, Peijun Guo, Subra Suresh, David C. Paine, Haneesh Kesari, Nitin P. Padture
Mechanical reliability plays an outsized role in determining the durability of flexible electronic devices because of the significant mechanical stresses they can experience during manufacturing and operation. These devices are typically built on sheets comprising stiff thin-film electrodes on compliant polymer substrates, and it is generally assumed that the high-toughness substrates do not crack easily. Contrary to this widespread assumption, here we reveal severe, pervasive, and extensive cracking in the polymer substrates during bending of electrode/substrate sheets, which compromises the overall mechanical integrity of the entire device. The substrate-cracking phenomenon appears to be general, and it is driven by the amplified stress intensity factor caused by the elastic mismatch at the film/substrate interface. To mitigate this substrate cracking, an interlayer-engineering approach is designed and experimentally demonstrated. This approach is generic, and it is potentially applicable to myriad flexible electronic devices that utilize stiff films on compliant substrates, for improving their durability and reliability.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
22 pages, 5 main figures, 7 supplementary figures, 2 supplementary tables, 2 supplementary notes
Interaction-driven quantum phase transitions between topological and crystalline orders of electrons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
André Haug, Ravi Kumar, Tomer Firon, Misha Yutushui, Kenji Watanabe, Takashi Taniguchi, David F. Mross, Yuval Ronen
Topological and crystalline orders of electrons both benefit from enhanced Coulomb interactions in partially filled Landau levels. In bilayer graphene (BLG), the competition between fractional quantum Hall liquids and electronic crystals can be tuned electrostatically. Applying a displacement field leads to Landau-level crossings, where the interaction potential is strongly modified due to changes in the orbital wave functions. Here, we leverage this control to investigate phase transitions between topological and crystalline orders at constant filling factors in the lowest Landau level of BLG. Using transport measurements in high-quality hBN-encapsulated devices, we study transitions as a function of displacement field near crossings of $ N=0$ and $ N=1$ orbitals. The enhanced Landau-level mixing near the crossing stabilizes electronic crystals at all fractional fillings, including a resistive state at $ \nu = \frac{1}{3}$ and a reentrant integer quantum Hall state at $ \nu = \frac{7}{3}$ . On the $ N=0$ side, the activation energies of the crystal and fractional quantum Hall liquid vanish smoothly and symmetrically at the transition, while the $ N=1$ transitions out of the crystal appear discontinuous. Additionally, we observe quantized plateaus forming near the crystal transition at half filling of the $ N=0$ levels, suggesting a paired composite fermion state stabilized by Landau level mixing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 4 figures, 27 pages supplemental, 20 supplemental figures
Charge Transfer Dynamics in an Electron-Hole Bilayer Device: Capacitance Oscillations and Hysteretic Behavior
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Miranda Leigh Davis, Simon Parolo, Sandro Agostini, Christian Reichl, Werner Dietsche, Werner Wegscheider
The capacitance and differential conductance of MBE-grown AlGaAs/GaAs p-i-n diodes are investigated. In these diodes, the p-doped layer, an adjacent intrinsic spacer, and a central barrier are made of AlGaAs. Capacitance oscillations and hysteretic behavior are observed and understood to be consequences of the AlGaAs spacer properties. These findings have significant implications for the design of heterostructures aimed at achieving electrically contacted, closely spaced electron and hole layers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Interface Magnetism in Vanadium-doped MoS$_2$/Graphene Heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Diem Thi-Xuan Dang, Yen Thi-Hai Pham, Da Zhou, Dai-Nam Le, Mauricio Terrones, Manh-Huong Phan, Lilia M. Woods
Magnetism in two-dimensional materials is of great importance in discovering new physical phenomena and developing new devices at the nanoscale. In this paper, first-principles simulations are used to calculate the electronic and magnetic properties of heterostructures composed of Graphene and MoS$ _2$ considering the influence of point defects and Vanadium doping. It is found that the concentration of the dopants and the types of defects can result in induced magnetic moments leading to ferromagnetically polarized systems with sharp interfaces. This provides a framework for interpreting the experimental observations of enhanced ferromagnetism in both MoS$ _2$ /Graphene and V-doped MoS$ _2$ /Graphene heterostructures. The computed electronic and spin polarizations give a microscopic understanding of the origin of ferromagnetism in these systems and illustrate how doping and defect engineering can lead to targeted property tunability. Our work has demonstrated that through defects engineering, ferromagnetism can be achieved in V-doped MoS$ _2$ /Graphene heterostructures, providing a potential way to induce magnetization in other TMDC/Graphene materials and opening new opportunities for their applications in nano-spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
27 pages, 8 pages, 1 table. Submitted
Classifying destructive quantum interference in molecular junctions: Towards molecular quantum rulers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Lukas Krieger, Gert-Ludwig Ingold, Fabian Pauly
Destructive quantum interference in molecular junctions might be used to build molecular quantum rulers, allowing to quantify changes in external control parameters electrically. For this reason, it is important to understand which patterns of destructive quantum interference can occur inside the electronic excitation gap of a molecule, coupled to conducting electrodes. By considering a four-level model, we show that much more complex destructive quantum interference behavior can arise than expected for just two levels. We classify the destructive quantum interferences analytically and show that they may even occur in regions forbidden by the standard orbital rule for electron transport. Our results suggest that appropriate molecular design may indeed allow to construct highly sensitive molecular quantum rulers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
10 pages, 9 figures
Magnetic excitations from the hexagonal spin clusters in the S = 1/2 distorted honeycomb lattice antiferromagnet Cu2(pymca)3(ClO4)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Masaaki Matsuda, Alexander I. Kolesnikov, Zentaro Honda, Tokuro Shimokawa, Sho Inoue, Yasuo Narumi, Masayuki Hagiwara
Cu2(pymca)3(ClO4) (pymca: pyrimidine-2-carboxylate) consists of a slightly distorted honeycomb lattice of Cu2+ spins, which shows no long-range magnetic order down to 0.6 K. A magnetization study revealed 1/3 and 2/3 plateau phases [A. Okutani et al., J. Phys. Soc. Jpn. 88, 013703 (2019)], which is not expected for regular honeycomb antiferromagnets. Inelastic neutron scattering experiments were performed using a powder sample to investigate the exchange interactions of this material. The spin excitations from the singlet ground state to the first three triplet states, predicted from the antiferromagnetic hexagonal spin cluster interacting with 3.9 meV, were observed. Using the exact diagonalization mothods, the intercluster coupling was estimated from the excitation peak width to be about 20% of the intracluster interaction, which is consistent with the previously reported value. Our exchange path model explains the anisotropic exchange interactions in the distorted honeycomb plane.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
6 pages, 6 figures
Ab initio Complex Langevin computation of the roton gap for a dipolar Bose condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Philipp Heinen, Wyatt Kirkby, Lauriane Chomaz, Thomas Gasenzer
We compute from first principles the dispersion relation $ \omega(k)$ of a dipolar Bose gas of erbium atoms close to the roton instability by employing the Complex Langevin (CL) algorithm. Other than the path integral Monte Carlo algorithm, which samples the quantum mechanical path integral in the $ N$ -particle basis, CL samples the field-theoretic path integral of interacting bosons and can be evaluated for experimentally realistic atom numbers. We extract the energy of roton excitations as a function of the s-wave scattering length, and compare our results to those from Gross-Pitaevskii theory, with and without quantum fluctuation corrections.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat)
10 pages, 6 figures
Higgs-mode electromagnon in the spin-spiral multiferroic CuBr${}_2$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Bryan T. Fichera, Ajesh Kumar, Baiqing Lv, Zongqi Shen, Karna Morey, Qian Song, Batyr Ilyas, Tianchuang Luo, Riccardo Comin, T. Senthil, Nuh Gedik
Below a continuous symmetry breaking phase transition, the relevant collective excitations are due to longitudinal and transverse fluctuations of the order parameter, which are referred to as Higgs and Goldstone modes, respectively. In solids, these modes may take on a different character than the equivalent excitations in particle physics due to the diverse vacuum states accessible in condensed matter. However, the Higgs mode in particular is quite difficult to observe experimentally as it decays quickly into the lower-energy Goldstone bosons and thus has a negligible lifetime in most systems. In this work, we report evidence for a novel Higgs mode in the multiferroic material CuBr$ {}_2$ , which shows up as a coherent oscillation in the time-resolved second harmonic generation signal upon excitation with a femtosecond light pulse. Since the spiral spin order in CuBr$ {}_2$ induces a nonzero electric dipole moment in equilibrium, the Higgs mode–which is due to fluctuations in the amplitude of the on-site spin expectation value–is an electromagnon, and thus acquires an inversion quantum number of -1. This is in stark contrast to the Higgs boson of particle physics, which has even parity. Moreover, the excitation described here represents an entirely new type of electromagnon, distinct from the traditional electromagnon in linear spin wave theory which is due to the Goldstone mode.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
29 pages, 10 figures
A Unified Predictive and Generative Solution for Liquid Electrolyte Formulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Zhenze Yang, Yifan Wu, Xu Han, Ziqing Zhang, Haoen Lai, Zhenliang Mu, Tianze Zheng, Siyuan Liu, Zhichen Pu, Zhi Wang, Zhiao Yu, Sheng Gong, Wen Yan
Liquid electrolytes are critical components of next-generation energy storage systems, enabling fast ion transport, minimizing interfacial resistance, and ensuring electrochemical stability for long-term battery performance. However, measuring electrolyte properties and designing formulations remain experimentally and computationally expensive. In this work, we present a unified framework for designing liquid electrolyte formulation, integrating a forward predictive model with an inverse generative approach. Leveraging both computational and experimental data collected from literature and extensive molecular simulations, we train a predictive model capable of accurately estimating electrolyte properties from ionic conductivity to solvation structure. Our physics-informed architecture preserves permutation invariance and incorporates empirical dependencies on temperature and salt concentration, making it broadly applicable to property prediction tasks across molecular mixtures. Furthermore, we introduce – to the best of our knowledge – the first generative machine learning framework for molecular mixture design, demonstrated on electrolyte systems. This framework supports multi-condition-constrained generation, addressing the inherently multi-objective nature of materials design. This unified framework advances data-driven electrolyte design and can be readily extended to other complex chemical systems beyond electrolytes.
Materials Science (cond-mat.mtrl-sci)
Engineering Graphene Nanoribbons via Periodically Embedding Oxygen Atoms
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Yan Zhao, Li-Xia Kang, Yi-Jun Wang, Yi Wu, Guang-Yan Xing, Shi-Wen Li, Jinliang Pan, Nie-Wei Wang, Yin-Ti Ren, Ying Wang, Ya-Cheng Zhu, Xing-Qiang Shi, Mengxi Liu, Xiaohui Qiu, Pei-Nian Liu, Deng-Yuan Li
Heteroatom doping is an important method for engineering graphene nanoribbons (GNRs) because of its ability to modify electronic properties by introducing extra electrons or vacancies. However, precisely integrating oxygen atoms into the lattice of GNRs is unexplored, and the resulting electronic properties remain elusive. Here, we achieve the precise embedding of oxygen atoms into the lattice of GNRs via in situ formation of pyrans, synthesizing two types of oxygen-doped GNRs (O-doped chevron-GNR and O-doped chiral (2,1)-GNR). Using scanning tunneling microscopy, non-contact atomic force microscopy, and density functional theory calculations, the atomic structures and electronic properties of O-doped GNRs are determined, demonstrating that both GNRs are direct bandgap semiconductors with different sensitivities to oxygen dopants. Oxygen dopants have a minor impact on the bandgap of chevron-GNR but a significant effect on the bandgap of chiral (2,1)-GNR, which is attributed to the difference in density of states near the Fermi level between substituted intrinsic carbon atoms and their pristine counterparts. Compared with the pristine chiral (2,1)-GNR, the band structure of O-doped chiral (2,1)-GNR exhibits unexpected band edges transition, which is ascribed to sp2-hybridized oxygen atoms which introduces additional electrons to the conduction band of chiral (2,1)-GNR, leading to the upward shift of Fermi surface.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Robust Wave Splitters Based on Scattering Singularities in Complex non-Hermitian Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Jared Erb, Nadav Shaibe, Tsampikos Kottos, Steven M. Anlage
Coherent perfect absorption (CPA) is well-known as a phenomenon where all the energy of a specific injected wavefront is completely absorbed by losses in a system, independent of details. This has applications in wavefront shaping, communication, filtering, wireless power transfer, etc. We have discovered an application of coherent perfect absorption enabling conditions as a tunable splitter that is robust to any change in relative amplitude or phase of an arbitrary injected waveform. We show experimentally that the fixed splitting ratios and output phases at CPA enabling conditions are robust to 100 dB of relative power and 2$ \pi$ phase changes of the input waves to a complex non-Hermitian two-port system. We also demonstrate that the splitting power ratio can be tuned by multiple orders of magnitude and the CPA enabling conditions can be tuned to any desired frequency with suitable tunable perturbations embedded in the system. Although this phenomenon is realized in two-port systems, tunable robust splitting can be achieved between any two ports of multiport systems. These results are general to all wave scattering phenomena and hold in generic complex scattering systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chaotic Dynamics (nlin.CD), Optics (physics.optics)
Three-Dimensional Fermi Surface, Van Hove Singularity and Enhancement of Superconductivity in Infinite-Layer Nickelates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Chengliang Xia, Shengjie Zhou, Hanghui Chen
Recent experiments reveal a three-dimensional (3D) Fermi surface with a clear $ k_z$ dispersion in infinite-layer nickelates, distinguishing them from their cuprate superconductor counterparts. However, the impact of this difference on the superconducting properties of nickelates remains unclear. Here, we employ a combined random-phase-approximation and dynamical-mean-field-theory (RPA+DMFT) approach to solve the linearized gap equation for superconductivity. We find that, compared to the cuprate-like two-dimensional (2D) single-orbital Fermi surface, the van Hove singularities on the 3D Fermi surface of infinite-layer nickelates strengthen spin fluctuations by driving the system closer to antiferromagnetic instabilities, thereby significantly enhancing superconductivity. Our findings underscore the critical role of the van Hove singularities in shaping the superconducting properties of infinite-layer nickelates and, more broadly, highlight the importance of subtle Fermi surface features in modeling material-specific unconventional superconductors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 4 figures
The Global Diffusion Limit for the Space Dependent Variable-Order Time-Fractional Diffusion Equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-29 20:00 EDT
Christopher N. Angstmann, Daniel S. Han, Bruce I. Henry, Boris Z. Huang, Zhuang Xu
The diffusion equation and its time-fractional counterpart can be obtained via the diffusion limit of continuous-time random walks with exponential and heavy-tailed waiting time distributions. The space dependent variable-order time-fractional diffusion equation is a generalization of the time-fractional diffusion equation with a fractional exponent that varies over space, modelling systems with spatial heterogeneity. However, there has been limited work on defining a global diffusion limit and an underlying random walk for this macroscopic governing equation, which is needed to make meaningful interpretations of the parameters for applications. Here, we introduce continuous time and discrete time random walk models that limit to the variable-order fractional diffusion equation via a global diffusion limit and space- and time- continuum limits. From this, we show how the master equation of the discrete time random walk can be used to provide a numerical method for solving the variable-order fractional diffusion equation. The results in this work provide underlying random walks and an improved understanding of the diffusion limit for the variable-order fractional diffusion equation, which is critical for the development, calibration and validation of models for diffusion in spatially inhomogeneous media with traps and obstacles.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Quantitative Methods (q-bio.QM)
Magnetic Dipole Trapping Potential between Infinite Superconducting Plates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
We derive the exact analytic form of the potential experienced by a magnetic dipole trapped between two infinite parallel superconducting plates using the method of image dipoles, providing a benchmark for numerical methods and a foundation for studying the stability and dynamics of magnetically levitated systems in precision measurements and fundamental physics experiments.
Superconductivity (cond-mat.supr-con), Applied Physics (physics.app-ph)
4 pages, 2 figures
Predicting Stress in Two-phase Random Materials and Super-Resolution Method for Stress Images by Embedding Physical Information
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Tengfei Xing, Xiaodan Ren, Jie Li
Stress analysis is an important part of material design. For materials with complex microstructures, such as two-phase random materials (TRMs), material failure is often accompanied by stress concentration. Phase interfaces in two-phase materials are critical for stress concentration. Therefore, the prediction error of stress at phase boundaries is crucial. In practical engineering, the pixels of the obtained material microstructure images are limited, which limits the resolution of stress images generated by deep learning methods, making it difficult to observe stress concentration regions. Existing Image Super-Resolution (ISR) technologies are all based on data-driven supervised learning. However, stress images have natural physical constraints, which provide new ideas for new ISR technologies. In this study, we constructed a stress prediction framework for TRMs. First, the framework uses a proposed Multiple Compositions U-net (MC U-net) to predict stress in low-resolution material microstructures. By considering the phase interface information of the microstructure, the MC U-net effectively reduces the problem of excessive prediction errors at phase boundaries. Secondly, a Mixed Physics-Informed Neural Network (MPINN) based method for stress ISR (SRPINN) was proposed. By introducing the constraints of physical information, the new method does not require paired stress images for training and can increase the resolution of stress images to any multiple. This enables a multiscale analysis of the stress concentration regions at phase boundaries. Finally, we performed stress analysis on TRMs with different phase volume fractions and loading states through transfer learning. The results show the proposed stress prediction framework has satisfactory accuracy and generalization ability.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Machine Learning (cs.LG)
Percolation in the two-dimensional Ising model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-29 20:00 EDT
Tao Chen, Jinhong Zhu, Wei Zhong, Sheng Fang, Youjin Deng
The study of the Ising model from a percolation perspective has played a significant role in the modern theory of critical phenomena. We consider the celebrated square-lattice Ising model and construct percolation clusters by placing bonds, with probability $ p$ , between any pair of parallel spins within an extended range beyond nearest neighbors. At the Ising criticality, we observe two percolation transitions as $ p$ increases: starting from a disordered phase with only small clusters, the percolation system enters into a stable critical phase that persists over a wide range $ p_{c_1} < p < p_{c_2}$ , and then develops a long-ranged percolation order with giant clusters for both up and down spins. At $ p_{c1}$ and for the stable critical phase, the critical behaviors agree well with those for the Fortuin-Kasteleyn random clusters and the spin domains of the Ising model, respectively. At $ p_{c2}$ , the fractal dimension of clusters and the scaling exponent along $ p$ direction are estimated as $ y_{h2} = 1.958,0(6)$ and $ y_{p2} = 0.552(9)$ , of which the exact values remain unknown. These findings reveal interesting geometric properties of the two-dimensional Ising model that has been studied for more than 100 years.
Statistical Mechanics (cond-mat.stat-mech)
11 pages, 9 figures
Micro-tip manipulated origami for robust twisted few-layer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Ruo-Jue Zou, Long Deng, Si-Min Xue, Feng-Fei Cai, Ling-Hui Tong, Yang Zhang, Yuan Tian, Li Zhang, Lijie Zhang, Zhihui Qin, Long-Jing Yin
Twisted few-layer graphene (tFLG) has emerged as an ideal model system for investigating novel strongly correlated and topological phenomena. However, the experimental construction of tFLG with high structural stability is still challenging. Here, we introduce a highly accessible method for fabricating robust tFLG by polymer micro-tip manipulated origami. Through using a self-prepared polymer micro-tip, which is composed of multiple dimethylpolysiloxane, poly(vinyl chloride), and graphite sheets, to fold graphene layers, we fabricated tFLG with different twist angles (0°-30°) and various layers, including twisted bilayers (1+1), twisted double-bilayers (2+2), twisted double-trilayers (3+3), and thicker layers. Even ABC-stacked tFLG were created, such as twisted ABC/ABC and ABC/ABA graphene coexisting in an ABC-ABA domain wall region. We found that the origami-fabricated tFLG exhibits high stability against thermal and mechanical perturbations including heating and transferring, which could be attributed to its special folding and tearing structures. Moreover, based on the rich types of samples, we revealed twist-angle and stacking-order dependent Raman characteristics of tFLG, which is valuable for understanding the stacking-modulated phonon spectroscopy. Our experiments provide a simple and efficient approach to construct structurally robust tFLG, paving the way for the study of highly stable twisted van der Waals heterostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 5 figures
Appl. Phys. Lett. 126, 163105 (2025) Featured Article & AIP Scilight
Structural transformation for BaBiO3-δ thin films grown on SrTiO3-buffered Si(001) induced by an in-situ Molecular Beam Epitaxy cooldown process
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Islam Ahmed, Olivier Richard, Partrick Carolan, Marco Gambin, Luca Ceccon, Moloud Kaviani, Stefan De Gendt, Clement Merckling
Oxygen loss is one of the common defect types in perovskite oxides whose formation can be caused by a low oxygen background pressure during growth or by straining the thin film. Crystalline BaBiO3-{\delta} thin films are grown by molecular beam epitaxy on SrTiO3 buffered Si(001) substrates. Adsorption-controlled regime governs the epitaxy, as the sticking coefficient of bismuth is boosted by supplying activated oxygen at plasma power of 600 W during epitaxy. Even though activated oxygen is supplied during the growth process, large amount of oxygen vacancies is found to be created in the thin film depending on the cooldown process. Perovskite structure is obtained when the cooldown process includes an extended period of time during which activated oxygen at plasma power of 600 W is supplied. Another way for inducing the structural transformation is enabled via an ex-situ 600°C anneal step at molecular oxygen for the sample which includes oxygen vacancy channels. The transformation into perovskite structure BaBiO3 is manifested as reconstructed octahedra based on transmission electron microscopy, Raman spectroscopy, and photoluminescence. Additionally, smaller out-of-plane lattice constant as well as increased monoclinicity are observed for the perovskite phase supported by X-ray diffraction data. In this paper, thermal mismatch and multivalency-facilitated tensile strain exerted on the layers by the underlying Si substrates are presented as the driving force behind the creation of oxygen vacancies.
Materials Science (cond-mat.mtrl-sci)
Planar Nernst effect from hidden band geometry in layered two-dimensional materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Rahul Biswas, Harsh Varsney, Amit Agarwal
The Nernst effect is a versatile phenomenon relevant for energy harvesting, magnetic sensing, probing band topology and charge-neutral excitations. The planar Nernst effect (PNE) generates an in-plane voltage transverse to an applied temperature gradient under an in-plane magnetic field. Conventional Berry curvature-induced PNE is absent in two-dimensional (2D) systems, as the out-of-plane Berry curvature does not couple to the in-plane electron velocity. We challenge this notion by demonstrating a distinct planar Nernst effect in quasi-2D materials (2DPNE). We show that the 2DPNE originates from previously overlooked planar components of Berry curvature and orbital magnetic moment, arising from inter-layer tunneling in multilayered 2D systems. We comprehensively analyze the band-geometric origin and crystalline symmetry constraints on 2DPNE responses. We illustrate its experimental feasibility in strained bilayer graphene. Our findings significantly expand the theoretical understanding of planar Nernst effects, providing a clear pathway for next-generation magnetic sensing and energy-harvesting applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 5 figures
In Situ Nanometer-Resolution Strain and Orientation Mapping for Gas-Solid Reactions via Precession-Assisted Four-dimensional Scanning Transmission Electron Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Yongwen Sun, Ying Han, Dan Zhou, Athanassios S. Galanis, Alejandro Gomez-Perez, Ke Wang, Stavros Nicolopoulos, Hugo Perez Garza, Yang Yang
Chemomechanical interactions in gas or liquid environments are crucial for the functionality and longevity of various materials used in sustainable energy technologies, such as rechargeable batteries, water-splitting catalysts, and next-generation nuclear reactors. A comprehensive understanding of nanoscale strain evolution involved in these processes can advance our knowledge of underlying mechanisms and facilitate material design improvements. However, traditional microscopy workflows face challenges due to trade-offs between field of view (FOV), spatial resolution, temporal resolution, and electron beam damage, particularly in gas or liquid environments. Here, we demonstrate in situ nanometer-resolution strain and orientation mapping in a temperature-controlled gas environment with a large FOV. This is achieved by integrating a microelectromechanical system (MEMS)-based closed-cell TEM holder, precession-assisted four-dimensional scanning transmission electron microscopy (4D-STEM), and a direct electron detector (DED). Using the strain evolution during zirconium initial oxidation as a case study, we first outline critical strategies for focused ion beam gas-cell sample preparation and gas-phase TEM workflows to enhance experimental success. We then show that integrating DED with precession electron diffraction and optimizing gas pressure substantially improve the quantity and quality of the detected Bragg peaks in nano-beam electron diffraction patterns, enabling more precise strain measurements. Furthermore, we introduce a practical protocol to pause the reactions, allowing sufficient time for 4D-STEM data collection while ensuring the temporal resolution needed to resolve material dynamics. Our methodology and workflow provide a robust framework for quantitative analysis of chemomechanical evolutions in materials exposed to gas or liquid environments.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Slow ferromagnetic fluctuations in the kagome metal Sc$_3$Mn$_3$Al$_7$Si$_5$ revealed by $^{27}$Al NMR
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Qing-Ping Ding, Charles Taylor, Yongbin Lee, Charuni Dissanayake, Vireshwar Mishra, Dang Khoa Le, Manh-Huong Phan, Yasuyuki Nakajima, Yuji Furukawa
Static and dynamical magnetic and electronic properties of the kagome metal Sc$ _3$ Mn$ _3$ Al$ _7$ Si$ _5$ have been investigated by $ ^{27}$ Al nuclear magnetic resonance (NMR) measurements. The temperature dependence of Knight shift ($ K$ ) shows a similar temperature dependence of the DC magnetic susceptibility $ \chi$ except for the low-temperature region below $ \sim$ 50 K where $ K$ is almost constant while $ \chi$ keeps increasing, which suggests that the increase in $ \chi$ at low temperatures is not intrinsic. $ ^{27}$ Al spin-lattice relaxation rate divided by temperature ($ 1/T_1T$ ) is found to be constant, confirming the metallic state of Sc$ _3$ Mn$ _3$ Al$ _7$ Si$ _5$ from a microscopic point of view. Based on a Korringa ratio analysis using the $ T_1$ and $ K$ data, ferromagnetic spin fluctuations are found to dominate in Sc$ _3$ Mn$ _3$ Al$ _7$ Si$ _5$ . These fluctuations are suggested to be very slow with frequencies on the order of kilohertz or lower.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
Critical Non-Hermitian Edge Modes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Kunling Zhou, Zihe Yang, Bowen Zeng, Yong Hu
We unveil a unique critical phenomenon of topological edge modes in non-Hermitian systems, dubbed the critical non-Hermitian edge modes (CNHEM). Specifically, in the thermodynamic limit, the eigenvectors of edge modes jump discontinuously under infinitesimal on-site staggered perturbations. The CNHEM arises from the competition between the introduced on-site staggered potentials and size-dependent non-reciprocal coupling between edge modes, and are closely connected to the exceptional point (EP). As the system size increases, the coupling between edge modes decreases while the non-reciprocity is enhanced, causing the
eigenvectors to gradually collapse toward the EP. However, when the on-site potentials dominate, this weakened coupling assists the eigenvectors to stay away from the EP. Such a critical phenomenon is absent in Hermitian systems, where the coupling between edge modes is reciprocal.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
5 pages, 2 figures
Anisotropy-dependent decay of room temperature metastable skyrmions and a nascent double-$q$ spin texture in Co${8}$Zn${9}$Mn$_{3}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
J. S. White, V. Ukleev, L. Yu, Y. Tokura, Y. Taguchi, K. Karube
Chiral cubic Co-Zn-Mn magnets exhibit diverse topological spin textures, including room-temperature skyrmion phases and robust far-from-equilibrium metastable states. Despite recent advances in understanding metastable skyrmions, the interplay between compositional disorder and varying magnetic anisotropy on the stability and decay of metastable textures, particularly near room temperature, remains incompletely understood. In this work, the equilibrium and metastable skyrmion formation in Co$ _{8}$ Zn$ _{9}$ Mn$ _{3}$ is examined, revealing transformations between distinct metastable spin textures induced by temperature and magnetic field. At room temperature, the decay dynamics of metastable skyrmions exhibits a strong dependence on magnetic anisotropy, showcasing a route towards tailoring relaxation behavior. Furthermore, a nascent double-$ q$ spin texture, characterized by two coexisting magnetic modulation vectors $ q$ , is identified as a minority phase alongside the conventional triple-$ q$ hexagonal skyrmion lattice. This double-$ q$ texture can be quenched as a metastable state, suggesting both its topological character, and its role as a potential intermediary of metastable skyrmion decay. These findings provide new insights into the tunability of equilibrium and metastable topological spin textures via chemical composition and magnetic anisotropy, offering strategies for designing materials with customizable and dynamic skyrmion properties for advanced technological applications.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
22 pages, 6 figures
Unraveling the Conglomeratic Nature of Methanol Clusters Adsorbed on Graphene Surfaces. Insights from Molecular Dynamics Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Juan García de la Concepción, Izaskun Jiménez-Serra, Ibon Alkorta, José Elguero, Pedro Cintas
The expression of chirality in adsorption phenomena constitutes an important topic, not only relevant to asymmetric transformations involving solid surfaces, but also to the emergence of homochirality in both terrestrial and extraterrestrial scenarios. Methanol (MeOH) aggregation on graphite/graphene, one of the most idealized adsorbate-adsorbent systems, lead to islands of cyclic clusters of different sizes (Nano. Lett., 2016, 16, 3142-3147). Here, we show that this aggregation occurs enantioselectively affording 2D conglomerates depending on the size of clusters, in close analogy to a Pasteurian racemate. Homochiral sequences are held together by hydrogen bonding and other non-covalent interactions, whose absolute configurations can be appropriately specified. A discussion involving the dichotomy between 2D racemates and conglomerates, is offered as well. In addition, the present simulations showcase a broad range of acyclic and cyclic structures, even if some discrete rings are the dominant species, in agreement with previous experimental data and theoretical modeling. Our results indicate that MeOH clusters show binding energies close to the experimental values, remaining intact at temperatures as high as 120 K and up to 150 K.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Superconductivity in a semiconductor doped with the resonance negative U-centers
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Serguei N. Burmistrov, Leonid B. Dubovskii
We study the effect of doping the semiconductor with the resonance negative U-centers upon its superconducting transition temperature. The attraction of electrons at the U-centers leads to the enhancement of transition temperature. On the contrary, the resonant scattering of conduction electrons along with their hybridization at the U-centers results in reducing the transition temperature. The largest effect on the superconducting transition temperature takes place if the resonance width is of the order of the energy level at the U-center. In the lack of the electron-phonon coupling under sufficiently low concentration of U-centers the superconducting transition is entirely absent in spite of the presence of attraction between electrons at U-centers.
Superconductivity (cond-mat.supr-con), Other Condensed Matter (cond-mat.other)
7 pages, 8 figures
Superconducting Quantum Interference Devices based on InSb nanoflag Josephson junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Andrea Chieppa, Gaurav Shukla, Simone Traverso, Giada Bucci, Valentina Zannier, Samuele Fracassi, Niccolo Traverso Ziani, Maura Sassetti, Matteo Carrega, Fabio Beltram, Francesco Giazotto, Lucia Sorba, Stefan Heun
Planar Josephson junctions (JJs) based on InSb nanoflags have recently emerged as an intriguing platform in superconducting electronics. This letter presents the fabrication and investigation of superconducting quantum interference devices (SQUIDs) employing InSb nanoflag JJs. We provide measurements of interference patterns in both symmetric and asymmetric geometries. The interference patterns in both configurations can be modulated by a back-gate voltage, a feature well reproduced through numerical simulations. The observed behavior aligns with the skewed current-phase relations of the JJs, demonstrating significant contributions from higher harmonics. We explore the magnetic field response of the devices across a wide range of fields ($ \pm 30$ mT), up to the single-junction interference regime, where a Fraunhofer-like pattern is detected. Finally, we assess the flux-to-voltage sensitivity of the SQUIDs to evaluate their performance as magnetometers. A magnetic flux noise of $ S^{1/2}_\Phi = 4.4 \times 10^{-6} \Phi_0 / \sqrt{Hz}$ is identified, indicating potential applications in nanoscale magnetometry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
Practical way to increase nonlinearity of kinetic inductance of superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Yu. P. Korneeva (1), M. A. Dryazgov (1), I. V. Trofimov (1), M. Yu. Levichev (2), N. V. Porokhov (1), A. M. Mumlyakov (1), M. V. Shibalov (1), D. Yu. Vodolazov (1 and 2), A. A. Korneev (1 and 3), M. A. Tarkhov (1) ((1) Institute of Nanotechnology of Microelectronics of the Russian Academy of Sciences, (2) Institute for Physics of Microstructures Russian Academy of Sciences, (3) Higher School of Economics - National Research University)
This work demonstrates that depositing a thin layer of Mo (5-15 nm) onto a 10 nm thick NbN strip leads to a significant increase in the nonlinearity of the kinetic inductance $ L_k$ . Specifically, the change in $ L_k$ with increasing current reached 70% in the NbN/Mo bilayer at liquid helium temperature, whereas in the NbN strip, $ L_k$ changed by only 10% in the superconducting state. In addition to altering the nonlinear properties, the Mo layer caused a significant increase in the critical current at low temperatures (up to 2 times in the case of a 5 nm thick Mo layer). The increased nonlinearity of $ L_k$ can be explained by two factors: i) a reduction of the critical supervelocity at which the superconducting state becomes unstable with respect to vortex formation when a Mo layer is deposited on NbN, and ii) a higher sensitivity of the induced superconductivity in Mo to supervelocity/supercurrent. Considering the results on the transport properties of SN bilayers with a high ratio of layer resistivities $ \rho_S/\rho_N >> 1$ , it can be concluded that depositing a thin layer of a relatively low-resistivity metal onto a superconductor with high $ \rho$ is a practical method for achieving a large nonlinearity of the superconductor’s kinetic inductance.
Superconductivity (cond-mat.supr-con)
Learning Stochastic Thermodynamics Directly from Correlation and Trajectory-Fluctuation Currents
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-29 20:00 EDT
Jinghao Lyu, Kyle J. Ray, James P. Crutchfield
Markedly increased computational power and data acquisition have led to growing interest in data-driven inverse dynamics problems. These seek to answer a fundamental question: What can we learn from time series measurements of a complex dynamical system? For small systems interacting with external environments, the effective dynamics are inherently stochastic, making it crucial to properly manage noise in data. Here, we explore this for systems obeying Langevin dynamics and, using currents, we construct a learning framework for stochastic modeling. Currents have recently gained increased attention for their role in bounding entropy production (EP) from thermodynamic uncertainty relations (TURs). We introduce a fundamental relationship between the cumulant currents there and standard machine-learning loss functions. Using this, we derive loss functions for several key thermodynamic functions directly from the system dynamics without the (common) intermediate step of deriving a TUR. These loss functions reproduce results derived both from TURs and other methods. More significantly, they open a path to discover new loss functions for previously inaccessible quantities. Notably, this includes access to per-trajectory entropy production, even if the observed system is driven far from its steady-state. We also consider higher order estimation. Our method is straightforward and unifies dynamic inference with recent approaches to entropy production estimation. Taken altogether, this reveals a deep connection between diffusion models in machine learning and entropy production estimation in stochastic thermodynamics.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (cs.LG), Adaptation and Self-Organizing Systems (nlin.AO), Machine Learning (stat.ML)
11 pages, 6 appendices (10 pages), 4 figures; this https URL
A Workflow for Correlative in-situ Nano-chip Liquid Cell Transmission Electron Microscopy and Atom Probe Tomography Enabled by Cryogenic Plasma Focused Ion Beam
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Neil Mulcahy, James O. Douglas, Syeda Ramin Jannat, Lukas Worch, Geri Topore, Baptiste Gault, Mary P. Ryan, Michele Shelly Conroy
Operando/in-situ liquid cell transmission electron microscopy (LCTEM) allows for real time imaging of dynamic nanoscale liquid-based processes. However, due to the thick liquid cell of traditional LCTEM holders and thus scattering of the electron beam passing through the cell, the achievable spatial and chemical resolution is limited. Cryogenic atom probe tomography (cryo-APT) overcomes these limitations by offering (near-)atomic scale compositional analysis of frozen liquid-solid interfaces. However, APT provides limited structural analysis and has no capacity for dynamic or operando liquid cell studies. This work presents a novel workflow for site-specific cryo-APT sample preparation of liquid-solid interfaces from in-situ electrochemical LCTEM Micro-Electro-Mechanical Systems (MEMS) chips. Using cryogenic inert gas transfer suitcase and a cryogenic plasma-focused ion beam (PFIB), a MEMs nanochip containing a Li electrolyte from an electrochemistry LCTEM holder was successfully frozen, transferred to the cryo stage of a PFIB and prepared into APT needle samples containing the electrolyte-electrode interface at cryogenic temperatures, followed by cryogenic transfer to an atom probe for nanoscale compositional analysis. This correlative approach provides dynamic nanoscale imaging and near atomic scale compositional analysis of liquid-solid interfaces. This method enables reliable and reproducible APT sample preparation of these frozen interfaces from MEMs based nanochips and can hence be used across materials systems and energy-conversion or storage devices.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Superconducting Sn-Intercalated TaSe$_2$: Structural Diversity Obscured by Conventional Characterization Techniques
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Brenna C. Bierman, Hongrui Ma, Ying Wang, Daniel A. Rhodes
Using Sn-intercalated TaSe$ _2$ as a model system, we uncover structural heterogeneity by single-crystal X-ray diffraction that eludes the common characterization techniques of powder X-ray diffraction, Raman spectroscopy, and electrical transport measurements. From a single growth composition (1:1:2 Sn:Ta:Se), we obtain diverse stoichiometries and structures, with near-continuous intercalation for Sn$ _x$ TaSe$ _2$ from $ 0\leq\textrm{x}\leq1$ . Using single-crystal X-ray diffraction, we identify four new structures: Sn$ _{0.18}$ TaSe$ _{1.92}$ ($ R3m$ ), Sn$ _{0.37}$ TaSe$ _{2.14}$ ($ R\bar3$ ), Sn$ _{0.42}$ TaSe$ _{2.04}$ ($ P\bar31c$ ), and Sn$ _{1.1}$ TaSe$ _2$ ($ Fmm2$ ). In contrast, powder X-ray diffraction cannot resolve all four structures. Raman spectroscopy is unable to distinguish different structures or compositions in the standard measurement range. Transport measurements show consistent superconductivity irrespective of Sn-intercalation amount or appearance of charge density wave behavior. This work underscores the inadequate sensitivity of common approaches in capturing the structural diversity of intercalated transition metal dichalcogenides and the need for high-resolution structural characterization when examining the properties of van der Waals-layered compounds.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Connecting weakly nonlinear elasticity theories of isotropic hyperelastic materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Yangkun Du, Nicholas A Hill, XIaoyu Luo
Soft materials exhibit significant nonlinear geometric deformations and stress-strain relationships under external forces. This paper explores weakly nonlinear elasticity theories, including Landau’s and Murnaghan’s formulations, advancing understanding beyond linear elasticity. We establish connections between these methods and extend strain-energy functions to the third and fourth orders in powers of epsilon, where epsilon is defined as the square root of the inner product of H with itself, epsilon = sqrt(H \ast H), and epsilon is between 0 and 1. Here, H represents the perturbation to the deformation gradient tensor, where the deformation gradient F is given by F = I + H. Furthermore, we address simplified strain-energy functions applicable to incompressible materials. Through this work, we contribute to a comprehensive understanding of nonlinear elasticity and its relationship to weakly nonlinear elasticity, facilitating the study of moderate deformations in soft material behavior and its practical applications.
Soft Condensed Matter (cond-mat.soft)
Mathematics and Mechanics of Solids 2025
Skyrmion Bubbles by Design in a Centrosymmetric Kagome Magnet
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Mohamed El Gazzah, Fehmi Sami Yasin, Sk Jamaluddin, Hari Bhandari, Resham Babu Regmi, Xiuzhen Yu, Nirmal J. Ghimire
Topologically protected nanoscale spin textures, such as magnetic skyrmions, have attracted significant interest for spintronics applications. While skyrmions in noncentrosymmetric materials are known to be stabilized by Dzyaloshinskii$ -$ Moriya interaction (DMI), their deliberate design in centrosymmetric materials remains a challenge. This difficulty largely stems from the complexity of controlling magnetocrystalline anisotropy $ -$ a critical factor in the absence of DMI. Here, we demonstrate the chemical tuning of magnetocrystalline anisotropy in the centrosymmetric Kagome magnet TmMn$ _6$ Sn$ _6$ . The resulting compound exhibits a spin reorientation transition accompanied by an emergent skyrmion bubble lattice, confirmed by Lorentz transmission electron microscopy. Our findings overcome a key materials design challenge and open possibilities for deliberate design of skyrmionic textures in centrosymmetric systems.
Materials Science (cond-mat.mtrl-sci)
Electric field tunable magnetoexcitons in Xenes-hBN-TMDC, Xenes-hBN-BP, and Xenes-hBN-TMTC heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Roman Ya. Kezerashvili, Anastasia Spiridonova, Klaus Ziegler
In this work, we propose novel van der Waals (vdW) heterostructures composed of Xenes, transition metal dichalcogenides (TMDCs), phosphorene, and transition metal trichalcogenides (TMTCs), which are separated by insulating hexagonal boron nitride (hBN) layers. We investigate theoretically the behavior of Rydberg indirect excitons in Xenes-hBN-TMDC, Xenes-hBN-BP, and Xenes-hBN-TMTC heterostructures, subject to parallel external electric and magnetic fields that are oriented perpendicular to the layers. By incorporating both isotropic and anisotropic materials, we demonstrate that excitonic properties can be effectively tuned through the external field strengths and the heterostructure design.
Our results show that the exciton reduced mass and the binding energy increase with the electric field strength, while enhanced dielectric screening from additional hBN layers reduces the binding energy. Anisotropic materials exhibit distinct excitonic responses, including variations in diamagnetic behavior. Moreover, the diamagnetic energy contributions and coefficients decrease with stronger electric fields but increase with the number of hBN layers. Finally, we explore the potential of time-periodic electric fields with Floquet band-structure engineering. These findings provide a comprehensive framework for controlling excitonic phenomena in low-dimensional materials, enabling the design of advanced optoelectronic and quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 6 figures
Anomalous phonon magnetic moments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Swati Chaudhary, Carl P. Romao, Dominik M. Juraschek
Circularly polarized phonons conventionally carry an angular momentum and a magnetic moment arising from the circular motions of the atoms around their equilibrium positions in a crystal. Here, we present three cases of anomalous magnetic moments produced by axial phonons that cannot be described in the conventional framework. The three cases include rotationless axial phonons, in which the atoms carry no real, but only pseudo, angular momentum and magnetic moments, diverging gyromagnetic ratios, in which a finite phonon magnetic moment is produced despite nearly vanishing phonon angular momentum, and noncollinear phonon magnetic moments, in which the angular momentum and magnetic moment of the axial phonon are not parallel. Our results shine light on the origin and nature of phonon magnetic moments and open a route towards phononic hidden orders and noncollinear phonomagnetism.
Materials Science (cond-mat.mtrl-sci)
Interplay of Coil-Globule Transitions and Aggregation in Homopolymer Aqueous Solutions: Simulation and Topological Insights
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Junichi Komatsu, Kenichiro Koga, Jonas Berx
We investigate the structural and topological behavior of interacting hydrophobic polymer chains in aqueous solutions by combining molecular dynamics simulations with circuit topology (CT) analysis. Combining geometric observables such as the radius of gyration and degree of aggregation with CT data we are able to capture the relationship between the coil-globule and aggregation transitions, resolving the underlying organizational changes of the system. Our results uncover a clear temperature-driven collective transition from isolated coiled polymers to aggregated globular clusters. This transition is reflected not only in conventional geometric descriptors but also in a striking reorganization of CT motifs: from dominant intrachain motifs at low temperatures to a rich ensemble of multichain motifs as temperature increases. We demonstrate that CT motif enumeration reproduces standard contact statistics via combinatorics while simultaneously providing a higher-order, topologically informed view of polymer organization. These findings highlight the power of CT as a structural descriptor for complex soft-matter systems and suggest broad applicability to biologically relevant phenomena.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
7 pages, 5 figures
Catalyst-mediated etching of carbon nanotubes exhibiting electronic-structure insensitivity and reciprocal kinetics with growth
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
The selective etching of carbon nanotubes has been widely explored as a post-synthetic route for enriching semiconducting species. As nanoelectronic applications increasingly demand pure semiconducting nanotubes for use in field-effect transistors and other optoelectronic devices, understanding the mechanistic basis of selective removal becomes critical. While etching selectivity is often attributed to electronic structure effects on tube walls, its relevance in the presence of catalyst nanoparticles remains unclear. Here, we directly quantify the catalyst-mediated etching and growth rates of individual single-walled carbon nanotubes using elaborate isotope labeling methods. Surprisingly, in water vapor and methanol environments, catalytic etching proceeds with negligible dependence on tube electronic type, in sharp contrast to non-catalytic oxidation pathways. In-situ Raman analysis upon heating on nanotube ensembles also confirms metallicity-insensitive etching under catalytic conditions, whereas sidewall oxidation without catalysts exhibits pronounced selectivity. Our growth kinetic model, which precisely describes the kinetics of catalytic etching process, motivates kinetic Monte Carlo simulations of nanotube edge dynamics, revealing the reciprocal nature of edge configuration during growth and etching. These findings highlight a fundamental mechanistic distinction between catalytic and non-catalytic reactivity and thus propose that catalytic etching may serve as a diagnostic mirror of growth behavior when using pre-sorted carbon nanotube samples.
Materials Science (cond-mat.mtrl-sci)
29 pages, 5 figures,13 pages of supplementary materials
Ab initio molecular dynamics of paramagnetic uranium mononitride (UN) using disordered local moments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Mohamed AbdulHameed, Benjamin Beeler
This work presents an investigation of the thermophysical properties of paramagnetic uranium mononitride (UN) using ab initio molecular dynamics (AIMD) simulations combined with the disordered local moment (DLM) approach. This methodology accurately captures the high-temperature paramagnetic state of UN, addressing the limitations of standard density functional theory (DFT) models. The AIMD+DLM model consistently predicts a cubic crystal structure for UN across all considered temperatures, aligning with experimental observations of its paramagnetic phase. Key thermophysical properties, including the lattice parameter and specific heat capacity, are computed and compared to experimental data. The calculated lattice parameter is somewhat underestimated relative to the empirical correlation, consistent with prior studies modeling UN as a ferromagnetic (FM) or antiferromagnetic (AFM) material. The specific heat capacity exhibits overestimation at low temperatures (300–500 K) and slight underestimation at higher temperatures, while closely following the experimental trend. These results highlight the accuracy and utility of the AIMD+DLM framework in modeling paramagnetic materials, which can offer insights into the influence of the magnetic state on the behavior of nuclear fuels at high temperatures.
Materials Science (cond-mat.mtrl-sci)
Different behaviors of diffusing diffusivity dynamics based on three different definitions of fractional Brownian motion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-29 20:00 EDT
Wei Wang, Aleksei V. Chechkin, Ralf Metzler
The effects of a “diffusing diffusivity” (DD), a stochastically time-varying diffusion coefficient, are explored within the frameworks of three different forms of fractional Brownian motion (FBM): (i) the Langevin equation driven by fractional Gaussian noise (LE-FBM), (ii) the Weyl integral representation introduced by Mandelbrot and van Ness (MN-FBM), and (iii) the Riemann-Liouville fractional integral representation (RL-FBM) due to L{é}vy. The statistical properties of the three FBM-generalized DD models are examined, including the mean-squared displacement (MSD), mean-squared increment (MSI), autocovariance function (ACVF) of increments, and the probability density function (PDF). Despite the long-believed equivalence of MN-FBM and LE-FBM, their corresponding FBM-DD models exhibit distinct behavior in terms of the MSD and MSI. In the MN-FBM-DD model, the statistical characteristics directly reflect an effective diffusivity equal to its mean value. In contrast, in LE-FBM-DD, correlations in the random diffusivity give rise to an unexpected crossover behavior in both MSD and MSI. We also find that the MSI and ACVF are nonstationary in RL-FBM-DD but stationary in the other two DD models. All DD models display a crossover from a short-time non-Gaussian PDF to a long-time Gaussian PDF. Our findings offer guidance for experimentalists in selecting appropriate FBM-generalized models to describe viscoelastic yet non-Gaussian dynamics in bio- and soft-matter systems with heterogeneous environments.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph), Quantitative Methods (q-bio.QM)
13 pages, 4 figures, RevTeX
Leveraging Modified Ex Situ Tomography Data for Segmentation of In Situ Synchrotron X-Ray Computed Tomography
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Tristan Manchester, Adam Anders, Julio Spadotto, Hannah Eccleston, William Beavan, Hugues Arcis, Brian J. Connolly
In situ synchrotron X-ray computed tomography enables dynamic material studies, but automated segmentation remains challenging due to complex imaging artefacts and limited training data. We present a methodology for deep learning-based segmentation by transforming high-quality ex situ laboratory data to train models for binary segmentation of in situ synchrotron data, demonstrated through copper oxide dissolution studies. Using a modified SegFormer architecture, our approach achieves high segmentation performance on unseen data while reducing processing time from hours to seconds per 3D dataset. The method maintains consistent performance over significant morphological changes during experiments, despite training only on static specimens. This methodology can be readily applied to diverse materials systems, accelerating the analysis of time-resolved tomographic data across scientific disciplines.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV)
In situ measurement of electrical resistivity evolution during dynamic compression of copper
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
K. Yan, Zhaokun Wang, Haijuan Mei, Wanting Sun
We report a novel experimental methodology for in situ measurement of electrical resistivity changes in T2 copper during dynamic compression utilizing a split Hopkinson pressure bar. The effects of adiabatic temperature rise and specimen shape deformation on the resistance were carefully accounted, which allowed one to isolate the contribution of microstructure changes such as dislocation evolution, defect generation, and lattice distortion. The latter allows for a real-time relationship between strain and electrical resistivity to be tracked. The experimental findings are also supplemented by molecular dynamics simulations that provide details about the process of microstructure evolution under dynamic loading. Up to now, very few in situ measurements has been carried out for changes in electrical resistivity during dynamic deformation, thus establishing a direct link for resistivity-strain which has important implications toward the understanding of plastic deformation and industrial application guidance.
Materials Science (cond-mat.mtrl-sci)
18 pages, 4 figures
Few-electron spin qubits in optically active GaAs quantum dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Peter Millington-Hotze, Petr Klenovsky, Harry E. Dyte, George Gillard, Santanu Manna, Saimon F. Covre da Silva, Armando Rastelli, Evgeny A. Chekhovich
The knowledge of the energy spectrum completely defines the dynamics of a quantum system for a given initial state. This makes spectroscopy a key characterization technique when studying or designing qubits and complex quantum systems. In semiconductor quantum dots, the electronic quantum states can be probed through charge transport spectroscopy, but the electric current itself disrupts the fragile quantum system, and the technique is practically limited to gate-defined quantum dots. Epitaxial quantum dots benefit from excellent optical properties, but are usually incompatible with charge transport, while alternative spectroscopy techniques provide only limited information. Here we demonstrate a spectroscopy technique which utilizes nuclear spins as a non-invasive probe. By using spin currents instead of the charge currents we achieve near-equilibrium probing. Experiments are conducted on low-strain GaAs/AlGaAs epitaxial dots, revealing energy spectra for charge configurations with up to seven electrons and the subtle properties of the multi-electron states. The rich variety of observations includes long-lived spin-qubit states in s and p shells, ground-state phase transitions, strong spin-orbit coupling regimes, and anomalously fast nuclear spin diffusion. Experiments are backed up by good agreement with the first-principles configuration-interaction numerical modelling. Our work uncovers few-electron states as a new operating regime for optically active quantum dots. Accurate control and probing of many-body states offers a test-bed system for fundamental physics studies, while prospective technological applications include electron spin qubits with extended coherence and scalable electrical control.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
$X$-type electrides hosting skin-like interstitial electron states and doping-enhanced superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Da-Bao Zha, Peng Jiang, Yan-Ling Li, Hai-Qing Lin
The exploration of electrides is of great significance for the fundamental physics due to their unique properties arising from interstitial anionic electrons. Here we report a novel class of $ X$ -type electrides, distinguished by two distinct anionic electron subchannels forming alternating chains in real space. Through structural symmetry analysis and first-principles calculations, we identify two-dimensional $ M_2$ N ($ M$ = Ti, Zr, Hf) materials as prototypical systems exhibiting these unique features. The anionic electron channels on the upper and lower surfaces of these materials display a vertically alternating pattern, with their projected bands revealing momentum-dependent splitting behavior in the reciprocal space, protected by a crystal symmetry operation $ O$ . Notably, the $ X$ -type electride characteristic is independent of the layer number and remains robust on the upper and lower surfaces of layered structures, presenting a pronounced skin-like effect. Additionally, we have explored the superconductivity of these systems, and found that both Ti$ _2$ N and Zr$ _2$ N are intrinsic superconductors with superconducting transition temperatures below 1.0 K. Further results show that appropriate hole doping can significantly enhance their superconducting transition temperatures and can induce the Hf$ _2$ N monolayer to exhibit superconductivity. Our findings provide valuable insights into the design and tuning of novel electrides with enhanced superconducting properties, offering a new pathway for deeply understanding the interplay between electride behavior and superconductivity in novel materials.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Control of active field theories at minimal dissipation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-29 20:00 EDT
Artur Soriani, Elsen Tjhung, Étienne Fodor, Tomer Markovich
Advances in experimental techniques enable the precise manipulation of a large variety of active systems, which constantly dissipate energy to sustain nonequilibrium phenomena without any equilibrium equivalent. To design novel materials out of active systems, an outstanding challenge is to rationalize how material properties can be optimally controlled by applying external perturbations. However, equilibrium thermodynamics is inadequate to guide the control of such nonequilibrium systems. Therefore, there is a dire need for a novel framework to provide a systematic toolbox for the thermodynamic control of active matter. Here, we build an optimization procedure for generic active field theories within a thermodynamically consistent formulation. Central to our approach is the distinction between the protocol heat, which is dissipated only during manipulation, and the total heat, which also accounts for the post-manipulation dissipation. We demonstrate that the latter generically features a global minimum with respect to the protocol duration. We deploy our versatile approach to an active theory of phase separation, and examine the scalings of the optimal protocol duration with respect to activity and system size. Remarkably, we reveal that the landscape of steady-state dissipation regulates the crossover between optimal control strategies for a finite duration.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
11 pages, 5 figures
CO$_2$ adsorption and photocatalytic reduction mechanisms on Ti-terminated CaTiO$_3$ (100) surface: a DFT study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Onofrio Tau, Giacomo Giorgi, Riccardo Rurali
Photoreduction of CO$ _2$ is an important alternative approach aimed to reduce the CO$ _2$ atmospheric content which is responsible of the global warming. The development of an efficient photocatalyst can strongly improve the efficiency and selectivity of the by-products of such a process. Recently, CaTiO$ _3$ has been used as an alternative semiconductor catalyst due to its attractive properties. In this study, we use calculations of the electronic structure of first principles to investigate for the first time the general reaction mechanism that leads to the main value-added by-products of HCOOH, CO, H$ _3$ COH and CH$ _4$ byproducts, focusing on the reactions of adsorption, activation and reduction reactions of CO$ _2$ molecules on the Ti-terminated CaTiO$ _3$ (100) surface. We compute adsorption energies of the various intermediate configurations and activation energy barriers of the chemical reaction pathways.
Our results show that CO$ _2$ can be activated by charge transfer of excess electrons leading to a CO$ _2$ anion that probably gives HCOO by the first reduction; however, the second hydrogenation to HCOOH is impeded by the prohibitive energy barrier. In particular, activated CO$ _2$ can also easily undergo decomposition, which facilitates CO production. Afterwards, we discuss the possible reaction mechanisms of CO photoreduction towards H$ _3$ COH and CH$ _4$ value-added products, taking into account the experimental evidence that only CO and CH$ _4$ have been detected. The reaction pathway generally follows the most energetically convenient routes characterized by activated intermediates. Even though H$ 3$ COH could be finally produced, its strong adsorption ($ E{ads}$ of -0.93 eV) and its promoted decomposition to H$ _3$ CO+H on the surface could explain why it has not been detected, as opposed to CH$ 4$ whose $ E{ads}$ is only -0.22 eV due to its non-polar nature.
Materials Science (cond-mat.mtrl-sci)
Synergistic Role of Transition Metals and Polyanionic Frameworks in Phosphate-Based Cathode Materials for Sodium-Ion Batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Madhav Sharma, Riya Gulati, Rajendra S. Dhaka
Ongoing research in the area of advanced cathode materials for sodium-ion batteries (SIBs) is expected to reduce reliance on lithium-ion batteries (LIBs), providing more affordable and sustainable energy storage solutions. Polyanionic compounds have emerged as promising options due to their stable structure and ability to withstand high-voltage conditions as well as fast charging capabilities. This review offers a thorough discussion of phosphate-based polyanionic cathodes for SIBs, exploring their structure, electrochemical performance with various transition metals, and existing challenges. We discuss different polyanionic frameworks, such as ortho-phosphates, fluoro-phosphates, pyro-phosphates, mix pyro-phosphates, and NASICON-based phosphates, highlighting their unique structural characteristics and ability to perform well across a wide potential range. Further, we delve into the mechanisms governing sodium storage and tunability of redox potentials in polyanionic materials, providing insights into the factors that affect their electrochemical performance. Finally, we outline future research directions and potential avenues for the practical applications of polyanionic high-voltage cathodes in sodium-ion battery technologies.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
to be published in Coordination Chemistry Reviews
Inverse Sandwich Geometry and Stability of B$_7$Y$_2$ Clusters: A DFT Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Peter Ludwig Rodríguez-Kessler
In this work, we use density functional theory (DFT) to investigate the structural and electronic properties of B$ _7$ Y$ _2$ clusters – boron frameworks doped with two yttrium atoms. Our results show that the most stable configuration adopts an inverse sandwich geometry, while higher-energy isomers ($ \sim$ 1.45 eV above) exhibit B$ _7$ wheel-like motifs with yttrium at top or bridge sites. To understand the bonding and stability, we analyze the electron localization function (ELF) and localized orbital locator (LOL) maps. The global minimum shows a symmetric, delocalized electron distribution, strong B-B covalent bonding, and partial charge transfer from Y atoms. In contrast, higher-energy isomers show less effective Y-B interactions. ELF and LOL analyses confirm electron delocalization within the boron framework. Mulliken population analysis reveals significant metal-to-boron charge transfer, contributing to the stability of the inverse sandwich structure through synergistic effects of delocalized bonding and charge redistribution.
Materials Science (cond-mat.mtrl-sci)
5 pages, 5 figures, 1 table
Fluctuation-induced first-order superfluid transition in unitary $\mathrm{SU}(N)$ Fermi gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
We investigate the superfluid phase transition in an $ \mathrm{SU}(N)$ -symmetric Fermi gas with $ N$ distinct spin states using the functional renormalization group. To capture pairing phenomena beyond mean-field theory, we introduce an auxiliary bosonic field and employ the leading order of the derivative expansion of the partially bosonized effective average action. By discretizing the effective potential on a grid and numerically integrating the flow equations, we resolve the thermodynamic behavior near the transition. Our results reveal a fluctuation-induced first-order phase transition for $ N \geq 4$ , which is absent at the mean-field level. In the unitary regime, we provide quantitative predictions for the critical temperature, as well as for the discontinuities in the superfluid gap and entropy density as functions of $ N$ . With increasing $ N$ , the critical temperature decreases, while the discontinuities become more pronounced, indicating a stronger first-order transition.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
Charge and pair density waves in a spin and valley-polarized system at a Van-Hove singularity
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
We study a single component (i.e., single valley, spin-polarized) two-dimensional electron gas with $ C_{3v}$ symmetry tuned to a Van-Hove (VH) singularity. Generically, there may be either three or six VH points at the Fermi level, related to each other by symmetry. Using a renormalization group analysis, we show that when the effective interactions between electrons at the VH points are positive, the system is stable. In contrast, if the effective interactions are negative, the system develops an instability toward either pair density wave (PDW) or charge density wave (CDW) orders, depending on the anisotropy of the dispersion at the VH points. The PDW may have either a single wavevector or multiple wavevectors. The PDW phase with three coexisting wavevectors can support fractional $ \tfrac{h}{6e}$ vortices. The interplay between the geometry of the Fermi surface and the singularity of the density of states is the key that enables PDW formation.
Strongly Correlated Electrons (cond-mat.str-el)
8+9 pages; 6+5 figures
Predicting neutron experiments from first principles: A workflow powered by machine learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Eric Lindgren, Adam J. Jackson, Erik Fransson, Esmée Berger, Svemir Rudić, Goran Škoro, Rastislav Turanyi, Sanghamitra Mukhopadhyay, Paul Erhart
Machine learning has emerged as a powerful tool in materials discovery, enabling the rapid design of novel materials with tailored properties for countless applications, including in the context of energy and sustainability. To ensure the reliability of these methods, however, rigorous validation against experimental data is essential. Scattering techniques – using neutrons, X-rays, or electrons – offer a direct way to probe atomic-scale structure and dynamics, making them ideal for this purpose. In this work, we describe a computational workflow that bridges machine learning-based simulations with experimental validation. The workflow combines density functional theory, machine-learned interatomic potentials, molecular dynamics, and autocorrelation function analysis to simulate experimental signatures, with a focus on inelastic neutron scattering. We demonstrate the approach on three representative systems: crystalline silicon, crystalline benzene, and hydrogenated scandium-doped BaTiO3, comparing the simulated spectra to measurements from four different neutron spectrometers. While our primary focus is inelastic neutron scattering, the workflow is readily extendable to other modalities, including diffraction and quasi-elastic scattering of neutrons, X-rays, and electrons. The good agreement between simulated and experimental results highlights the potential of this approach for guiding and interpreting experiments, while also pointing out areas for further improvement.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
12 pages, 7 figures
Time-reversal symmetry breaking in microscopic single-crystal Sr$_2$RuO$_4$ devices
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Remko Fermin, Matthijs Rog, Guido Stam, Daan Wielens, Joost Ridderbos, Chuan Li, Yoshi Maeno, Jan Aarts, Kaveh Lahabi
Time-reversal symmetry breaking superconductivity is a quintessential unconventional quantum state. In Josephson junctions, time-reversal symmetry breaking manifests itself in the supercurrent interference pattern as the invariance of the critical current under the reversal of both transport and magnetic field directions, i.e., $ I_\text{c+}(H) = I_\text{c-}(-H)$ . So far, such systems have been realized in devices where superconductivity is injected into a deliberately constructed weak link medium, usually carefully tuned by external magnetic fields and electrostatic gating. In this work, we report time-reversal symmetry breaking in spontaneously emerging Josephson junctions without intentionally constructed weak links. This is realized in ultra-pure single-crystal microstructures of Sr$ 2$ RuO$ 4$ , an unconventional superconductor with a multi-component order parameter. Here, the Josephson effect emerges intrinsically at the superconducting domain wall, where the degenerate states partially overlap. In addition to violating $ I\text{c+}(H) = I\text{c-}(-H)$ , we find a rich variety of exotic transport phenomena, including a supercurrent diode effect present in the entire interference pattern, two-channel critical current oscillations with a period that deviates from $ \Phi_0$ , fractional Shapiro steps, and current-switchable bistable states with highly asymmetric critical currents. Our findings provide direct evidence of TRSB in unstrained Sr$ _2$ RuO$ _4$ and reveal the potential of domain wall Josephson junctions, which can emerge in any superconductor where the pairing symmetry is described by a multi-component order parameter.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Composable and adaptive design of machine learning interatomic potentials guided by Fisher-information analysis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Weishi Wang, Mark K. Transtrum, Vincenzo Lordi, Vasily V. Bulatov, Amit Samanta
An adaptive physics-informed model design strategy for machine-learning interatomic potentials (MLIPs) is proposed. This strategy follows an iterative reconfiguration of composite models from single-term models, followed by a unified training procedure. A model evaluation method based on the Fisher information matrix (FIM) and multiple-property error metrics is proposed to guide model reconfiguration and hyperparameter optimization. Combining the model reconfiguration and the model evaluation subroutines, we provide an adaptive MLIP design strategy that balances flexibility and extensibility. In a case study of designing models against a structurally diverse niobium dataset, we managed to obtain an optimal configuration with 75 parameters generated by our framework that achieved a force RMSE of 0.172 eV/Å and an energy RMSE of 0.013 eV/atom.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Numerical Analysis (math.NA), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
18 pages, 7 figures, and 6 tables
Discrete Time Crystal in quantum Sherrington-Kirkpatrick model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-29 20:00 EDT
Discrete time crystals (DTC) have emerged as significant phase of matter for out-of-equilibrium many-body systems in recent years. Here, we study the role of long-range interactions and disorder in stabilizing the DTC phase. Generally, it is believed that a stable DTC phase can be realized in disordered systems with short-range interactions. We study the periodically driven quantum Sherrington-Kirkpatrick (SK) model of Ising spin-glass in which all spins are coupled to each other with random couplings. We explore the possibility of DTC phase within three different driving protocols. For all the cases, quantum SK model shows a robust DTC phase with no initial state dependence at all. We compare the periodically driven SK model with other models of long-range interactions with uniform coefficients where randomness is induced through a local field. In complete contrast to the SK model, these models show strong initial state dependence with a large number of initial states showing decay in periodic oscillations in spin-spin correlation function with time.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
Melting of a Bosonic Mott Insulator in Kagome Optical Lattices with Sign-Inverted Hopping
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Kazuma Nagao, Daisuke Yamamoto, Seiji Yunoki, Ippei Danshita
Using the discrete truncated Wigner approximation (dTWA), we investigate the nonequilibrium dynamics of ultracold bosons confined in optical kagome lattices, focusing on both unfrustrated positive and frustrated negative hopping regimes. We consider a protocol in which the system is initialized in a Mott insulating state at unit filling, and the hopping amplitude is gradually increased from zero. For positive hopping, the melting of the Mott insulator is accompanied by the emergence of a sharp peak in the momentum distribution at the $ \Gamma$ point of the lowest band, signaling the onset of superfluidity. In contrast, for negative hopping, the Mott insulator melts into a highly nontrivial state without long-range phase coherence, characterized instead by a broad momentum distribution within the flat band, consistent with recent experimental observations. These results demonstrate the applicability of dTWA to highly frustrated quantum systems and offer a new route for numerically exploring the dynamics of frustrated quantum magnets.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
7+7 pages, 4+6 figures
Controlling second-order rogue matter wave and line bright soliton dynamics in 2D Bose-Einstein Condensate with higher-order interactions and gain/loss atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
C.E. Nkenfack, O.T. Lekeufack, S. Sabari, R. Yamapi, T.C. Kofane
We investigate the two-dimensional modified Gross-Pitaevskii equation, accounting for the effects of atom gain/loss and a time-independent isotropic confining potential, utilizing the Hirota’s bilinear method. Through an appropriate bilinear form, we derive exact one-soliton and multi-soliton solutions. These solutions showcase two prominent phenomena: the second-order rogue matter wave with spatio-temporal localization, and the line soliton with double spatial localization. We demonstrate the feasibility of controlling the soliton amplitude and the effects of gain/loss resulting in areas of collapse by suitably tuning the coefficient of higher-order interactions in the Bose-Einstein condensate. Additionally, by exploring the interaction dynamics of the multi-soliton solutions, we identify elastic-type interactions, claiming the intrinsic properties of solitons. The influence of higher-order interactions and gain/loss terms on the interaction dynamics is also thoroughly analyzed. These analyses demonstrate that, within the framework of Bose-Einstein condensates described by the two-dimensional modified Gross-Pitaevskii equation, higher-order interactions provide a means to control the properties of the generated rogue matter waves. Extensive numerical simulations have been carried out, and their convergence with the theoretically predicted results highlights the emergent features of the obtained solutions. The exact analytical solutions derived in this study rigorously satisfy the original governing equation, thereby ensuring their consistency with the numerical findings and confirming their accuracy. Thus, our findings hold promise for potential future applications.
Quantum Gases (cond-mat.quant-gas)
29 figures, 3 movies and 25 pages
Interplay of Conventional and Spin-Exchange Auger Recombination in Magnetically Doped Quantum Dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Valerio Pinchetti, Ho Jin, Clément Livache, Victor I. Klimov
Auger processes play a critical role in the behavior of colloidal quantum dots (QDs). While nonradiative Auger recombination is a key performance-limiting factor in light-emitting applications, Auger effects also present exciting opportunities for hot-carrier manipulation in emerging optoelectronic and photochemical technologies. Recent studies have shown that incorporating magnetic manganese (Mn) dopants into QDs enables an ultrafast spin-exchange (SE) mechanism that significantly accelerates Auger recombination and related processes. However, the fundamental dynamics of SE-Auger recombination, including its dependence on QD size, exciton multiplicity, and Mn-ion content, remain largely unexplored. Here, we investigate SE-Auger recombination in Mn-doped QDs across three regimes defined by the energetic alignment between the QD band-edge exciton and the internal Mn spin-flip transition: resonant, downhill, and uphill, corresponding to the exciton energy being approximately equal to, greater than, or smaller than the Mn spin-flip transition energy, respectively. We find that SE-Auger recombination dominates multiexciton dynamics in both resonant and downhill regimes, proceeding on ultrafast, sub-picosecond timescales, that is, significantly faster than conventional Auger decay. Notably, SE-Auger lifetimes are primarily governed by the occupancy of intrinsic excitonic states, with minimal dependence on QD size or the number of excited Mn ions. In the uphill regime, SE-Auger recombination coexists with conventional Auger processes, enabling direct comparison of their timescales alongside co-occurring hot-carrier cooling. These findings establish that SE-Auger recombination outpaces phonon-assisted cooling, making it uniquely suited for the generation and manipulation of hot carriers, and opening new avenues in advanced photoconversion and photochemistry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Main text (19 pages), 6 main figures, and Supplementary Information (1 Note, 8 figures, and 2 tables)
Signatures of Hund$’s$ metal physics in single-layered 3d transition metal oxide, $\mathrm{Sr_2CoO_4}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Shivani Bhardwaj, Sudhir Kumar Pandey
With density functional theory plus dynamical mean-field theory, we study the influence of Hund’s coupling on the nature of electronic correlations in $ \mathrm{Sr_2CoO_4}$ . Our results suggest strong signatures of Hund’s metal physics in this compound. The Co 3$ d$ states show large orbital differentiation in the degree of correlations and mass enhancement. The imaginary-time correlation functions suggest the presence of spin-orbital separation and large local charge fluctuations in the system. Breakdown of the Fermi-liquid picture is observed at the lowest calculated temperature for various strengths of Hund’s coupling, suggesting the Fermi-liquid coherence scale lower than $ \sim$ 100 K. Interestingly, a sudden emergence of a gapped state is noted for $ e_g$ orbitals in its spectral density of states at $ \sim$ 200 K in the vicinity of Fermi-level. Among the Co 3$ d$ states 3$ d_{z^2}$ and 3$ d_{x^2-y^2}$ foster enlarged correlations. This study conclusively identifies $ \mathrm{Sr_2CoO_4}$ as the first single-layered 3$ d$ transition metal oxide to be classified as Hund’s metal.
Strongly Correlated Electrons (cond-mat.str-el)
Gapped Boundaries of Kitaev’s Quantum Double Models: A Lattice Realization of Anyon Condensation from Lagrangian Algebras
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Mu Li (1, 2, 3), Xiaohan Yang (4, 5), Xiao-Yu Dong (4) ((1) Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China, (2) International Quantum Academy, Shenzhen, China, (3) Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China, (4) Hefei National Laboratory, University of Science and Technology of China, Hefei, China, (5) Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei, China)
The macroscopic theory of anyon condensation, rooted in the categorical structure of topological excitations, provides a complete classification of gapped boundaries in topologically ordered systems, where distinct boundaries correspond to the condensation of different Lagrangian algebras. However, an intrinsic and direct understanding of anyon condensation in lattice models, grounded in the framework of Lagrangian algebras, remains undeveloped. In this paper, we propose a systematic framework for constructing all gapped boundaries of Kitaev’s quantum double models directly from the data of Lagrangian algebras. Central to our approach is the observation that bulk interactions in the quantum double models admit two complementary interpretations: the anyon-creating picture and anyon-probing picture. Generalizing this insight to the boundary, we derive the consistency condition for boundary ribbon operators that respect the mathematical axiomatic structure of Lagrangian algebras. Solving these conditions yields explicit expressions for the local boundary interactions required to realize gapped boundaries. Our construction provides a microscopic characterization of the bulk-to-boundary anyon condensation dynamics via the action of ribbon operators. Moreover, all these boundary terms are supported within a common effective Hilbert space, making further studies on pure boundary phase transitions natural and convenient. Given the broad applicability of anyon condensation theory, we believe that our approach can be generalized to extended string-net models or higher-dimensional topologically ordered systems.
Strongly Correlated Electrons (cond-mat.str-el), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
29 pages, 16 figures
Stokes drag on a sphere in a three-dimensional anisotropic porous medium
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Andrej Vilfan, Bogdan Cichocki, Jeffrey C. Everts
We study the hydrodynamic drag force exerted on a sphere in a static anisotropic porous medium. This problem is analysed using the Brinkman-Debye-Bueche equations with an axisymmetric shielding (or permeability) tensor. Using the exact Green’s functions for this model fluid within a single-layer boundary element formulation, we numerically compute the friction tensor for a translating sphere subjected to stick boundary conditions. Furthermore, we derive approximate analytical expressions for small anisotropy using the Lorentz reciprocal theorem. By benchmarking this result against the numerical solutions, we find that a linear approximation is valid in a broad parameter regime. Our results are important for studying self-diffusion in general anisotropic porous media, but can also be applied to small tracers in nematic fluids composed of disk- or rod-like crowders.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
9 pages, 4 figures
Maximizing Infrared Transmission Contrast Upon Phase Transition of Thermally Grown Vanadium Dioxide Thin Films by Rapid Thermal Processing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Ken Araki, Vishwa Krishna Rajan, Liping Wang
Pristine vanadium dioxide (VO2), an insulator-to-metal transition (IMT) material, is grown via furnace oxidation followed by rapid thermal annealing with forming gas (5%H2/95%N2) which reduces surface over-oxides such as V2O5 formed during the oxidation. The evolutional IMT behaviors of the thermochromic film and vanadium oxide states over different reduction time are systematically studied with temperature-dependent infrared spectrometry, electrical resistivity, and X-ray diffraction measurements. After optimally reducing surface over-oxides to VO2, infrared transmission contrast upon phase transition is enhanced to 46% (at 9 um wavelength) compared to 23% from fully oxidation without any reduction. Moreover, pristine VO2 thin film obtained from thermal oxidation and optimal reduction processes exhibits sharp phase transition and narrow thermal hysteresis within 2~4°C in both infrared transmission and electrical resistivity, which are comparable to the VO2 of best quality prepared by other sophisticated fabrication techniques. The thermally grown method presented here would facilitate the scalable fabrication of high-quality VO2 thin films and tunable radiative coatings for high-performance thermal control applications.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Spin-Depairing-Induced Exceptional Fermionic Superfluidity
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Soma Takemori, Kazuki Yamamoto, Akihisa Koga
We investigate the non-Hermitian (NH) attractive Hubbard model with spin depairing, which is a spin-resolved asymmetric hopping that nonreciprocally operates spins in the opposite direction. We find that spin depairing stabilizes a superfluid state unique to the NH system. This phase is characterized not only by a finite order parameter, but also by the emergence of exceptional points (EPs) in the momentum space - a feature that starkly contrasts with previously discussed NH fermionic superfluidity, where EPs are absent within the superfluid state and emerge only at the onset of the superfluid breakdown. We uncover the rich mechanism underlying this ``exceptional fermionic superfluidity’’ by analyzing the interplay between EPs and the effective density of states of the complex energy dispersion. Furthermore, we reveal that the exceptional superfluid state breaks down induced by strong spin depairing on the cubic lattice, while it remains robust on the square lattice.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
10 pages, 6 figures
Evolution of cavities in BCC-Fe with coexisting H and He under fusion environments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Jin Wang, Fengping Luo, Tao Zheng, Bowen Zhang, Yuxin Liu, Denghuang Chen, Xinyue Xie, Mohan Chen, Hong-Bo Zhou, Fei Gao, Jianming Xue, Yugang Wang, Chenxu Wang
In the fusion environment, understanding the synergistic effects of transmutation-produced hydrogen (H), helium (He), and irradiation-induced displacement damage in iron-based alloys is crucial for the development of structural materials for fusion reactors. When H and He atoms are simultaneously introduced into the matrix, the interaction between irradiation-induced cavity defects (voids and bubbles) with H and He, along with their evolutionary behavior remains poorly understood. In this study, the evolutionary behavior of cavities in body-centered cubic (BCC) iron (Fe) with H and He atoms is systematically investigated through a combination of molecular dynamics (MD) calculations and statistical thermodynamics. First, an efficient and suitable set of Fe-H-He ternary potential functions for describing interatomic interactions is established. Based on the newly developed MD model, the evolutionary behavior of H/He atoms and cavities is systematically investigated under various temperature and cavity structure conditions. Specifically, the kinetic process of H/He capture by cavities is elucidated for different scenarios. Additionally, thermodynamic analyses are employed to assess the feasibility of cavity trapping of H under varying conditions. The results exhibit strong consistency with experimental results and provide significant evidence supporting the formation of the core-shell structure (where He is confined at the cavity center while H accumulates at the surface) from both kinetic and thermodynamic perspectives. This work provides mechanistic insights into the nucleation and growth of cavities over extended temporal and spatial scales in the presence of H-He synergies.
Materials Science (cond-mat.mtrl-sci), Atomic and Molecular Clusters (physics.atm-clus), Atomic Physics (physics.atom-ph)
Thermodiffusion mechanism for the formation of an amorphous phase during the quenching of a metal melt
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
A. I. Karasevskii, A. Yu. Naumuk
A theoretical model of the formation of an amorphous phase during the quenching of a metallic melt is proposed. It has been shown that the appearance of a significant temperature gradient during the quenching of a metallic melt leads to thermodiffusion of defects and their outflow from the melt volume, which manifests itself in a significant reduction in the number of free spaces for the diffusion transfer of the atoms of the melt. Due to the thermodiffusion process, a significant restructuring of the microstructure of the medium occurs, which leads to a significant increase in viscosity, a decrease in the diffusion coefficient and specific volume of the substance, and changes in the mechanisms of deformation. The corresponding calculations of temperature distribution, thermodiffusion and distribution of the components of the melt have been carried out.
Materials Science (cond-mat.mtrl-sci)
Evolution of quantum criticality in underdoped cuprates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Changshuai Lan, Chengyu Yan, Yihang Li, Qiao Chen, Huai Guan, Xinming Zhao, Dong Wu, Butian Zhang, Youwei Zhang, Shun Wang
Quantum criticality, with both static and dynamic information of the system intrinsically encoded in characteristic length scales, serves as one of the most sensitive and universal probes to monitor quantum phase transition. Qualitatively different quantum criticality behaviours have been widely observed even in the same condensed matter system. The discrepancy is attributed to sample specificity but has not been systemically addressed. Here we report a single-parameter driven three-stage evolution of quantum criticality unveiled in superconductor-insulator transition in underdoped Bi2Sr2CaCu2O8+{\delta} flakes. The evolution starts with a single quantum critical point emerging at the boundary between the superconducting and antiferromagnetic phases, then evolving into anomalous quantum Griffiths singularity at the medium doping levels and eventually being replaced by quantum Griffiths singularity in the deep superconducting regime. A puddle model that incorporates the developments of antiferromagnetic correlation can capture the evolution. The results offer a new aspect to examine previous seemingly sample-specific quantum critical behavior and lay the foundation for further exploring complex quantum criticality in strongly correlated systems; meanwhile they shed light on the detailed interaction between superconductivity and antiferromagnetism in cuprates.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 5 figures
Cholic Acid-Based Mixed Micelles as siRNA Delivery Agents for Gene Therapy
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Alexander J Cunningham, Victor Passos Gibson, Xavier Banquy (UdeM), X.X. X Zhu, Jeanne Leblond Chain (ARNA)
Gene therapy is a promising tool for the treatment of various cancers but is hindered by the physico-chemical properties of siRNA and needs a suitable vector for the delivery of siRNA to the target tissue. Bile acid-based block copolymers offers certain advantages for the loading and delivery of siRNA since they can efficiently complex siRNA and bile acids are biocompatible endogenous molecules. In this study, we demonstrate the use of lipids as co-surfactants for the preparation of mixed micelles to improve the siRNA delivery of cholic acid-based block copolymers. Poly(allyl glycidyl ether) (PAGE) and poly(ethylene glycol) (PEG) were polymerized on the surface of cholic acid to afford a star-shaped block copolymer with four arms (CA-PAGE-b-PEG)4. The allyl groups of PAGE were functionalized to bear primary or tertiary amines and folic acid was grafted onto the PEG chain end to increase cell uptake. (CA-PAGE-b-PEG)4 functionalized with either primary or tertiary amines show high siRNA complexation with close to 100% complexation at N/P ratio of 8. Uniform aggregates with diameters between 181 and 188 nm were obtained. DOPE, DSPE-PEG2k, and DSPE-PEG5k lipids were added as co-surfactants to help stabilize the nanoparticles in the cell culture media. Mixed micelles had high siRNA loading with close to 100% functionalization at N/P ratio of 16 and diameters ranging from 153 to 221 nm. The presence of lipids in the mixed micelles improved cell uptake with a concomitant siRNA transfection in HeLa and HeLa-GFP model cells, respectively.
Soft Condensed Matter (cond-mat.soft)
International Journal of Pharmaceutics, 2020, 578, pp.119078
How rigidity percolation and bending stiffness shape colloidal gel elasticity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Dispersed colloidal particles within a suspension can aggregate and spontaneously self-organize into a robust, percolating structure known as a gel. These network-like structures are prevalent in nature and play a critical role in many industrial processes, including those involving batteries, food products, and pharmaceutical formulations. In this paper, we examine the emergence of elasticity in colloidal gels. We show that gelation is governed by a rigidity percolation transition. We identify a characteristic correlation length that quantifies the extent of elastic and structural inhomogeneities, which diverges at the critical point. Our findings reveal that, regardless of the interaction types, the particle concentration, or the specific route to non-ergodicity i.e. the preparation protocol, the elastic moduli and vibrational properties of gels can be accurately predicted within a unifying framework, in which the bending modes of fractal clusters – approximately the size of this correlation length – dominate under small deformations.
Soft Condensed Matter (cond-mat.soft)
Fermionizing the ideal Bose gas via topological pumping
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Maciej Marciniak, Grigori E. Astrakharchik, Krzysztof Pawłowski, Bruno Juliá-Díaz
We investigate the coherence and correlations of many-body states appearing in topological pumping in a one-dimensional Bose gas. By analyzing the system at zero and infinite interaction strengths, we reveal a rescaling of momentum distributions accompanied by a self-similar behavior in first- and second-order correlation functions. In excited states of non-interacting bosons, the momentum distribution shows a comb-like structure similar to that of non-interacting fermions but at a higher density. This is mirrored by Friedel oscillations in the one-body density matrix. At the same time, the density-density correlations still exhibit the bosonic enhancement. Our work illustrates how topological pumping induces a nontrivial mapping between bosonic and fermionic correlations.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Two-dimensional Dual-Switchable Ferroelectric Altermagnets: Altering Electrons and Magnons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
ShuaiYu Wang, Wei-Wei Wang, Jiaxuan Fan, Xiaodong Zhou, Xiao-Ping Li, Lei Wang
Ferroelectric altermagnets (FEAMs) offer unique magnetoelectric coupling properties by combining the characteristics of both antiferromagnets and ferromagnets, yet their multifunctional electric control remains largely unexplored. Here, we introduce and investigate a scenario for the simultaneous electrical switching of electronic spin and magnonic chirality splitting in two-dimensional FEAMs. Based on the C2DB database, employing symmetry analysis and first-principles calculations, we study prototypical candidates CrPS$ _3$ and V$ _2$ I$ _2$ O$ _2$ BrCl. We identify the mechanism: ferroelectricity arises from asymmetric displacements (P along $ z$ in CrPS$ _3$ , V along the $ xy$ -direction in V$ _2$ I$ _2$ O$ _2$ BrCl), which inherently couples electric polarization to both electronic and magnonic degrees of freedom by retaining [C$ _2$ ||$ M] symmetry. Our calculations explicitly demonstrate that reversing the ferroelectric polarization concurrently switches the sign of the electronic spin splitting and chirality of magnonic modes. This shows these materials as dual-switchable FEAMs, enabling unified electrical manipulation of electron and magnon properties. A potentially experimentally detectable method via the magneto-optical Kerr effect was derived. This work provides a materials-specific realization and theoretical basis for designing novel electrically controlled multifunctional spintronic, spin caloritronic, and magnonic devices.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
A Universal Spin-Orbit-Coupled Hamiltonian Model for Accelerated Quantum Material Discovery
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Yang Zhong, Rui Wang, Xingao Gong, Hongjun Xiang
The accurate modeling of spin-orbit coupling (SOC) effects in diverse complex systems remains a significant challenge due to the high computational demands of density functional theory (DFT) and the limited transferability of existing machine-learning frameworks. This study addresses these limitations by introducing Uni-HamGNN, a universal SOC Hamiltonian graph neural network that is applicable across the periodic table. By decomposing the SOC Hamiltonian into spin-independent and SOC correction terms, our approach preserves SU(2) symmetry while significantly reducing parameter requirements. Based on this decomposition, we propose a delta-learning strategy to separately fit the two components, thereby addressing the training difficulties caused by magnitude discrepancies between them and enabling efficient training. The model achieves remarkable accuracy (mean absolute error of 0.0025 meV for the SOC-related component) and demonstrates broad applicability through high-throughput screening of the GNoME dataset for topological insulators, as well as precise predictions for 2D valleytronic materials and transition metal dichalcogenide (TMD) heterostructures. This breakthrough eliminates the need for system-specific retraining and costly SOC-DFT calculations, paving the way for rapid discovery of quantum materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
15 pages,8 figures
Magnetic order and Li-diffusion in the 1/3-filled Kagome layers of antiperovskite Lithium-ion battery materials (Li$_2$Fe)SO and (Li$_2$Fe)SeO
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
F. Seewald, T. Schulze, N. Gräßler, F. L. Carstens, L. Singer, M.A.A. Mohamed, S. Hampel, B. Büchner, R. Klingeler, H.-H. Klauss, H.-J. Grafe
The recently discovered lithium-rich antiperovskites (Li$ _2$ Fe)SeO and (Li$ _2$ Fe)SO host lithium and iron ions on the same atomic position which octahedrally coordinates to central oxygens. In a cubic antiperovskite these sites form Kagome planes stacked along the <111> directions which triangular motifs induce high geometric frustration in the diluted magnetic sublattice for antiferromagnetic interactions. Despite their compelling properties as high-capacity Li-ion battery cathode materials, very little is known about the electronic and magnetic properties of lithium-rich antiperovskites. We report static magnetization, Mössbauer, and NMR studies on both compounds. Our data reveal a Pauli paramagnetic-like behaviour, a long-range antiferromagnetically ordered ground state below 50 K and a regime of short-range magnetic correlations up to 100 K. Our results are consistent with a random Li-Fe distribution on the shared lattice position. In addition, Li-hopping is observed above 200 K with an activation energy of E$ _a$ = 0.47 eV. Overall, our data elucidate static magnetism in a disordered magnetically frustrated and presumably semimetallic system with thermally induced ion diffusion dynamics.
Materials Science (cond-mat.mtrl-sci)
14 pages, 14 figures
Step conductance and spin selectivity in a one dimensional tailored conical magnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Using an S-matrix formulation we evaluate the conductance of a one dimensional free electron gas in double exchange interaction with a conical magnet. We find integer conductance steps depending on the energy window of the incoming electrons for conical magnets in different orientations and a modulated magnetic field profile. The conductance windows, that we attribute to potential or diffractive scattering, are characterized by spin selectivity depending on the magnetic field direction and chirality.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech)
5 pages, 6 figures
From local to collective superconductivity in proximitized graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Stefano Trivini, Tim Kokkeler, Jon Ortuzar, Eva Cortés-del Río, Beatriz Viña Bausá, Pierre Mallet, Jean-Yves Veuillen, Juan Carlos Cuevas, Ivan Brihuega, F. Sebastian Bergeret, Jose Ignacio Pascual
The superconducting proximity effect induces pairing correlations in metallic systems via Andreev scattering. This effect is particularly intriguing in graphene, as it enables two-dimensional superconductivity that is tunable through doping. Understanding how superconducting correlations propagate within the metal is crucial to unveiling the key factors behind this tunability. Here, we employ scanning tunneling microscopy to investigate the energy and length scales of the proximity effect induced by Pb islands on graphene. Using tip-induced manipulation, we assemble S/N/S junctions with tunable N-region spacing and explore the evolution of the proximitized state in the confined normal region. We find that different doping levels can lead to either localized or collective superconducting states. By combining our experimental results with quasiclassical theory, we demonstrate that interface conductance plays a key role in determining the strength and coherence length of pairing correlations and inter-island coupling. Our findings provide new insights into the design of novel superconducting states and the control of their properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Molecular Dynamics Investigation of Static and Dynamic Interfacial Properties in Ice-Polymer Premelting Layers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Takumi Sato, Ikki Yasuda, Noriyoshi Arai, Kenji Yasuoka
Premelting at the ice-polymer interfaces, in which a quasi-liquid layer (QLL) forms below the melting point, is strongly influenced by polymer surface chemistry; however, the molecular-scale mechanisms underlying these effects remain poorly understood. This study employs large-scale molecular dynamics simulations combined with machine learning-assisted analysis to elucidate how polymer type (hydrophilic vs hydrophobic) modulates interfacial premelting. Our simulations reveal that hydrophilic and hydrophobic polymer surfaces have distinct effects on the QLL thickness, interfacial water structure, and diffusivity. Specifically, a hydrophilic polymer interface promotes a thicker QLL with more ordered interfacial water and lower diffusivity, whereas a hydrophobic interface induces a thinner QLL with a less ordered interfacial water structure and higher diffusivity. These results advance the understanding of polymer-mediated interfacial melting phenomena and offer guidance for designing anti-icing and low-friction materials.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
5 pages, 7 figures
Non-Equilibrium Multiplet Excitations probed by the $M_{5,4}$ Branching Ratio in $3d \rightarrow 4f$ X-ray Absorption Spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Tim Amrhein, Beyza Salantur, Ralph Püttner, Niko Pontius, Karsten Holldack, Ru-Pan Wang, Christian Schüßler-Langeheine, Martin Weinelt, Nele Thielemann-Kühn
We show that ultrafast electronic $ 4f$ multiplet transitions in terbium metal are manifested by changes in the relative spectral weight of the $ M_5$ and $ M_4$ X-ray absorption resonances. Our experimental results are supported by a simulation of excited multiplet spectra with atomistic calculations; they prove that the so-called third rule of Thole and van der Laan, which relates the branching ratio of the spin-orbit split resonances to the total angular momentum $ J$ of the excited ion, is also valid in non-equilibrium. The presented detection scheme allows to detect $ J$ -changing excitation, \textit{i.e}, alterations of spin and orbital states, even in samples without net magnetization. This makes branching-ratio spectroscopy a powerful tool for the quantitative investigation of ultrafast changes in angular momentum $ J$ .
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
manuscript: 6 pages, 2 figures | supplements: 9 pages, 3 figures
Ferroelectric and Hyper Dielectric modes in Ferronematic Liquid Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Rahul Uttam, Neelam Yadav, Alexander Belik, Wanhe Jiang, Georg H. Mehl, Jagdish K. Vij, Yuri P. Panarin
Binary mixtures of the ferronematic compound DIO with recently reported non-ferroelectric material WJ-16 which shows Colossal Permittivity (CP) ~5000 and superparaelectricity (SPE) were studied by POM, electrical switching studies, and dielectric spectroscopy. Three mixtures with different contents of WJ-16 as 10, 25 and 50% in DIO as host were prepared. Our original expectation was the development of new nematic materials with both ferroelectric nematic (NF) and non-ferroelectric CP phases. The non-ferroelectric phase in mixtures exhibits a CP mode originally observed in pure WJ-16 and was termed as superparaelectric. However, the dielectric spectroscopy of mixtures shows two distinct relaxation processes: the typical paraelectric response and the CP mode. Therefore, this CP mode cannot be called superparaelectric and is redefined it as Hyper Dielectric mode. This is the first direct demonstration of materials with both ferroelectric and Hyper-dielectric phases in liquid crystalline materials. The hyper dielectric phase has a good potential as a working media for supercapacitors industry.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
24 pages, 9 Figures, 2 Tables, Submitted to J,this http URL
Oscillation death by mechanochemical feedback
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Phanindra Dewan, Soumyadeep Mondal, Sumantra Sarkar
Many cellular proteins, such as ERK, undergo oscillation death when cells are compressed, initiating many developmental processes in organisms. Whether such a transition arises from these proteins’ specific biochemistry or generic dynamical features remains unclear. In this paper, we show that coupling mechanics to the chemistry of Hopf oscillators, such as ERK, through mechanochemical feedback (MCF) can generically drive oscillation death upon compression. We demonstrate this result using an active solid, a 1D ring of Brusselators coupled through damped springs, which we term Harmonic Brusselator Ring (HBR). Because of MCF, HBR’s dynamics is non-Hermitian and breaks $ \mathcal{PT}$ -symmetry in a scale-dependent manner, generating a rich array of patterns, including traveling pulses, chimera states, intermittent fluctuations, and collective oscillation death. Furthermore, MCF engenders three dynamic phase transitions that separate the observed patterns into four phases. The underlying symmetry of HBR implies that the observed patterns and phases may generically arise in many natural and synthetic systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Pattern Formation and Solitons (nlin.PS), Biological Physics (physics.bio-ph)
6 pages (main text), 4 figures
Neuronal correlations shape the scaling behavior of memory capacity and nonlinear computational capability of recurrent neural networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-04-29 20:00 EDT
Reservoir computing is a powerful framework for real-time information processing, characterized by its high computational ability and quick learning, with applications ranging from machine learning to biological systems. In this paper, we demonstrate that the memory capacity of a reservoir recurrent neural network scales sublinearly with the number of readout neurons. To elucidate this phenomenon, we develop a theoretical framework for analytically deriving memory capacity, attributing the decaying growth of memory capacity to neuronal correlations. In addition, numerical simulations reveal that once memory capacity becomes sublinear, increasing the number of readout neurons successively enables nonlinear processing at progressively higher polynomial orders. Furthermore, our theoretical framework suggests that neuronal correlations govern not only memory capacity but also the sequential growth of nonlinear computational capabilities. Our findings establish a foundation for designing scalable and cost-effective reservoir computing, providing novel insights into the interplay among neuronal correlations, linear memory, and nonlinear processing.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (cs.LG), Neurons and Cognition (q-bio.NC)
19 pages, 8 figures
Orbital enhanced intrinsic nonlinear planar Hall effect for probing topological phase transition in CuTlSe$_{2}$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Fan Yang, Xu-Tao Zeng, Huiying Liu, Cong Xiao, Xian-Lei Sheng, Shengyuan A. Yang
The intrinsic nonlinear planar Hall effect proposed in recent studies offers a new way to probe intrinsic band geometric properties in a large class of materials. However, the search of material platforms with a large response remains a problem. Here, we suggest that topological Weyl semimetals can host enhanced intrinsic nonlinear planar Hall effect. From a model study, we show that the enhancement is mainly from the orbital contribution, and the response coefficient exhibits a characteristic resonance-like lineshape around the Weyl-point energy. Using first-principles calculations, we confirm these features for the concrete material CuTlSe$ _{2}$ . Previous studies have reported two different topological states of CuTlSe$ _{2}$ . We find this difference originates from two slightly different structures with different lattice parameters. We show that the nonlinear planar Hall response is much stronger in the Weyl semimetal state than in the topological insulator state, and the large response is indeed dominated by orbital contribution amplified by Weyl points. Our work reveals a close connection between nonlinear orbital responses and topological band features, and suggests CuTlSe$ _{2}$ as a suitable platform for realizing enhanced nonlinear planar Hall effect.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
8 pages, 7 figures
Eppur si muove: Shape of topological defects – in active nematics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Giacomo Marco La Montagna, Sumeja Burekovic, Ananyo Maitra, Cesare Nardini
Topological defects in systems with liquid-crystalline order are crucial in determining their large-scale properties. In active systems, they are known to have properties impossible at equilibrium: for example, $ +1/2$ defects in nematically-ordered systems self-propel. While some previous theoretical descriptions relied on assuming that the defect shape remains unperturbed by activity, we show that this assumption can lead to inconsistent predictions. We compute the shape of $ -1/2$ defects and show that the one of $ +1/2$ is intimately related to their self-propulsion speed. Our analytical predictions are corroborated via numerical simulations of a generic active nematic theory.
Soft Condensed Matter (cond-mat.soft)
Spectroscopic signature of anisotropic order parameter in Kagome lattice superconductor LaRh$_3$B$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Mona Garg, Nikhlesh S. Mehta, Ghulam Mohmad, Savita Chaudhary, Yogesh Singh, Goutam Sheet
The physics of the Kagome metal LaRh$ _3$ B$ _2$ along with its superconductivity below 2.6 K, unlike other popular Kagome metals, is not known to be significantly influenced by the electron correlations. While the indirect techniques to probe the bulk superconducting properties of LaRh$ _3$ B$ _2$ indicate a conventional isotropic order parameter, we show that the direct spectroscopic determination of the superconducting energy gap reveals an anomalous suppression of Andreev reflection between LaRh$ _3$ B$ _2$ and a normal metal. This observation hints to the presence of incomplete superconducting gap formation, at least along certain momentum directions, and consequent low-lying quasiparticle states. An analysis of multiple Andreev reflection spectra captured at different points on the surface of LaRh$ _3$ B$ _2$ reveals a distribution of the superconducting energy gap which is consistent with an anisotropic superconducting order parameter.
Superconductivity (cond-mat.supr-con)
19 pages, 5 figures
Exploring binary intermetallics for advanced interconnect applications using ab initio simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Kiroubanand Sankaran, Kristof Moors, Jean-Philippe Soulié, Christoph Adelmann, Geoffrey Pourtois
The challenge of increasing copper (Cu) resistivity with diminishing Cu interconnect dimensions in complementary metal-oxide-semiconductor (CMOS) transistors, along with the imperative for efficient electron transport paths to fulfill scaling requirements in interconnects is significant. First-principles electronic structures calculations based on density functional theory have been performed to evaluate the potential scalability of some Cu, Al, Ru and Mo based binary alloys to replace Cu. We evaluate the expected sensitivity of the resistivity of these binary alloys to reduced line dimensions with a figure of merit that is based on generalized finite-temperature transport tensors. These transport tensors allow for a straightforward comparison between highly anisotropic intermetallics with given transport directions and Cu, and are evaluated together with their resistance to electromigration. Based on the figure-of-merit analysis, we identify several aluminides that show potential to outperform Cu at reduced interconnect dimensions in terms of their electronic transport and reliability properties.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
5 pages, 1 figure
Non-Classical Spin-Phonon Correlations Induced by Rydberg Facilitation in a Lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Daniel Brady, Michael Fleischhauer
We investigate the interplay between mechanical forces and the internal-state dynamics of a chain of Rydberg atoms trapped in tweezer arrays under the facilitation constraint. Dipole interactions between Rydberg atoms couple electronic (spin) degrees of freedom with excited motional (phonon) states. We show that this interaction leads to highly correlated and non-classical phonon states in the form of squeezed center of mass position states of the Rydberg atoms. Coupling with either a normal or an inverted Lennard-Jones-type potential, resulting from an avoided crossing of Rydberg potential curves, leads to in-phase or out-of-phase correlated oscillations in the atom positions respectively. Furthermore, the growth dynamics of a finite cluster of excited Rydberg atoms can be mapped to the dynamics of a single particle in a semi-infinite lattice subject to a linear potential gradient caused by spin-phonon interactions. This results in Bloch oscillations in the spin cluster size, which in turn localize spin excitations in the system.
Quantum Gases (cond-mat.quant-gas)
Dimer in the Hubbard model. Exact and approximate solutions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Within the tight-binding model taking into account the Coulomb repulsion of electrons at one site (the Hubbard model), an exact calculation of the Fourier transform of the anticommutator Green’s function of the C2 dimer as a structural element of fullerene, the poles of which determine the energy spectrum of the studied nanosystem, was performed. Graphic representations of the equation for the chemical potential and the density of state of electrons were obtained. A solution for the dimer was obtained within the approximation of static fluctuations. The Fourier transform of the anticommutator Green’s function, obtained in the approximation of static fluctuations, coincided with a similar function obtained within the exact solution. The ionization energy and electron affinity were calculated and found to be 11.87 eV and 3.39 eV, respectively. It was concluded that the method for solving the Hubbard model for the C2 dimer in the approximation of static fluctuations proposed in the work can be a fairly adequate method for theoretical study of strongly correlated systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
14 pages, 6 figures
Theory of Non-Linear Electron Relaxation in Thin Gold Films and Their Signatures in Optical Observables
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Jonas Grumm, Malte Selig, Holger Lange, Andreas Knorr
Based on the momentum-resolved Boltzmann equation, we provide self-consistent numerical calculations of the dynamics of conduction electrons in thin noble metal films after linear and non-linear optical excitations with infrared and terahertz frequencies. Focusing exclusively on electron-phonon interaction, orientational relaxation is introduced and acts as dephasing of the optical excitation on a scale of tens of fs. In the linear regime, our numerical results agree with the experimental fits to a Drude model and predicts for non-linear excitations a field strength dependency of the orientational relaxation rate. In the THz regime, where the orientational relaxation proceeds faster than the oscillation cycle of the excitation THz field, a new high order dissipative Kerr-type non-linearity is predicted. This non-linearity originates from the Pauli blocking included in the electron-phonon scattering and results in a non-linearly increasing transmission of the film, detectable in experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
joint submission with the letter entitled “Ultrafast Electrons in Noble Metals: Orientational Relaxation, Thermalization and Cooling in Terms of Electron-Phonon Interaction”
Ultrafast Electrons in Noble Metals: Orientational Relaxation, Thermalization and Cooling in Terms of Electron-Phonon Interaction
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
We investigate the momentum-resolved dynamics of conduction electrons in noble metals following ultrashort optical excitation with linearly polarized light. Using a momentum-resolved Boltzmann equation approach for electron-phonon interaction, we solve for the combined effects of orientational relaxation, thermalization, and cooling. We introduce momentum orientational relaxation as the initial step in the equilibration of an optically excited non-equilibrium electron gas by highlighting its importance for the optical response of noble metals and the dephasing of plasmonic excitations. Our numerical results for gold reveal that orientational relaxation exists independently of the absorbed optical energy and dominates on time scales on the first tens of fs after excitation. Incorporating also thermalization and cooling on times up to a few ps, our approach provides a simultaneous description of optical and thermal properties of noble metals under initial non-equilibrium conditions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
joint submission with the regular article entitled “Theory of Non-Linear Electron Relaxation in Thin Gold Films and Their Signatures in Optical Observables”
The charge cycle of group IV vacancy centers in diamond: From DFT to rate equations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Joshua Claes, Bart Partoens, Dirk Lamoen
The silicon vacancy center in diamond is a promising system for quantum technologies due to its exceptional optical and spin properties. This has led to great interest in the silicon-vacancy center as well as in the other group IV vacancy centers. In this work, we model the charge cycle of the group IV vacancy centers from the $ -2$ to $ 0$ charge state. As a first step, we compute the onset energies for all relevant one- and two-step ionization processes. Based on these results, we then derive the rate equations using Fermi’s golden rule.
Materials Science (cond-mat.mtrl-sci), Atomic Physics (physics.atom-ph), Computational Physics (physics.comp-ph), Optics (physics.optics), Quantum Physics (quant-ph)
Bio-Derived Graphite from Pterocarpus marsupium Leaves for rGO-MoO$_3$ Nanocomposites with Enhanced Photocatalytic Efficiency
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
P. Princeya Mary, M. Kumaresavanji, P. Sundara Venkatesh, N. Kannan, V. Vasumathi
This study presents a sustainable approach to synthesize bio-graphite from Pterocarpus marsupium (Indian Kino) leaves without using chemical catalysts, activating agents, or organic solvents. The resulting bio-graphite was used to produce reduced graphene oxide (rGO) via a modified Hummers method. The bio-graphite derived rGO was further incorporated with orthorhombic structured MoO$ _3$ at different percentages (1, 3, and 6 wt.%) using ultrasonication. Structural, morphological, and functional characterizations were conducted using XRD, FESEM, FTIR, and UV-Vis DRS spectroscopy, revealing a bandgap of 2.82 eV for the rGO(3 wt.%)-MoO$ _3$ composite. Photocatalytic activity was evaluated via methylene blue degradation under natural sunlight. The rGO(3 wt.%)-MoO$ _3$ nanocomposite showed superior performance, achieving 90% degradation in 150 minutes when compared to 65% by pure MoO$ _3$ . The Scavenger tests confirmed superoxide radicals $ (\cdot O_2^-)$ as the main reactive species. This work highlights the potential of bio-graphite derived rGO-MoO$ _3$ nanocomposites as efficient, eco-friendly photocatalysts for wastewater treatment.
Materials Science (cond-mat.mtrl-sci)
23 pages,10 figures. This manuscript has been submitted to the “ Materials Science & Engineering B “
St4DeM: A software suite for multi-modal 4D-STEM acquisition techniques
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Toni Uusimaeki, Cheuk-Wai Tai, Tom Willhammar, Thomas Thersleff, Hasan Ali, Seda Ulusoy, Meltem Sezen, Bora Derin
A suite of acquisition applications related to the 4D-STEM technique is presented as a software package written within the Digital Micrograph environment, which is a widely used software platform in worldwide electron microscopy laboratories. The 4D-STEM technique allows the acquisition of diffraction patterns at each electron probe position in a scanning transmission electron microscope map. This suite includes 4D-STEM acquisition, ptychography, EELS/EDS spectrum imaging, tomography and basic virtual visualization and alignment methods on 4D data including incoherent differential phase contrast analysis. By integrating electron tomography with 4D-STEM and EELS SI, St4DeM enables the acquisition and analysis of 7-dimensional data.
Materials Science (cond-mat.mtrl-sci)
$η$-pairing states in the Hubbard model with non-uniform Hubbard interaction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
The existence of $ \eta $ -pairing eigenstates in the fermionic Hubbard model is fundamentally rooted in the $ \eta $ -pairing symmetry, which may hold for systems with non-uniform Hubbard interaction $ U$ . In this work, we present a generalized Hubbard model containing a variety of pseudo-spin terms that break the SO$ _{4}$ symmetry but retain the $ \eta $ -pairing symmetry. This allows us to construct a variety of correlated systems possessing $ \eta $ -pairing eigenstates.\ We exemplify our findings by considering a modified Hubbard model associated with alternative magnetic fields and on-site repulsion. We find that the same quasi-$ \eta $ -pairing eigenstate exhibits two distinct dynamic behaviors in the two models. Numerical results of the time evolution driven by several typical Hamiltonians accord with the analytic predictions and provide a way of the control of an $ \eta $ -pairing wavepacket with the aid of a time-dependent Hamiltonian.
Strongly Correlated Electrons (cond-mat.str-el)
Interpretable machine learning-guided design of Fe-based soft magnetic alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Aditi Nachnani, Kai K. Li-Caldwell, Saptarshi Biswas, Prince Sharma, Gaoyuan Ouyang, Prashant Singh
We present a machine-learning guided approach to predict saturation magnetization (MS) and coercivity (HC) in Fe-rich soft magnetic alloys, particularly Fe-Si-B systems. ML models trained on experimental data reveals that increasing Si and B content reduces MS from 1.81T (DFT2.04 T) to ~1.54 T (DFT1.56T) in Fe-Si-B, which is attributed to decreased magnetic density and structural modifications. Experimental validation of ML predicted magnetic saturation on Fe-1Si-1B (2.09T), Fe-5Si-5B (2.01T) and Fe-10Si-10B (1.54T) alloy compositions further support our findings. These trends are consistent with density functional theory (DFT) predictions, which link increased electronic disorder and band broadening to lower MS values. Experimental validation on selected alloys confirms the predictive accuracy of the ML model, with good agreement across compositions. Beyond predictive accuracy, detailed uncertainty quantification and model interpretability including through feature importance and partial dependence analysis reveals that MS is governed by a nonlinear interplay between Fe content, early transition metal ratios, and annealing temperature, while HC is more sensitive to processing conditions such as ribbon thickness and thermal treatment windows. The ML framework was further applied to Fe-Si-B/Cr/Cu/Zr/Nb alloys in a pseudo-quaternary compositional space, which shows comparable magnetic properties to NANOMET (Fe84.8Si0.5B9.4Cu0.8 P3.5C1), FINEMET (Fe73.5Si13.5B9 Cu1Nb3), NANOPERM (Fe88Zr7B4Cu1), and HITPERM (Fe44Co44Zr7B4Cu1. Our fundings demonstrate the potential of ML framework for accelerated search of high-performance, Co- and Ni-free, soft magnetic materials.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Machine Learning (cs.LG)
24 Pages, 6 Figure, 1 Table
TDP-43 multidomains and RNA modulate interactions and viscoelasticity in biomolecular condensates
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Yui Matsushita, Ikki Yasuda, Fuga Watanabe, Eiji Yamamoto
RNA-binding proteins form biomolecular condensates with RNA through phase separation, playing crucial roles in various cellular processes. While intrinsically disordered regions (IDRs) are key drivers of phase separation, additional factors such as folded domains and RNA also influence condensate formation and physical properties. However, the molecular mechanisms underlying this regulation remain elusive. Here, using molecular dynamics simulations, we investigate how the multidomain structure of TDP-43, which consists of its IDR, RNA recognition motifs (RRMs), and N-terminal domain (NTD), interacts with RNA and affects the characteristics of phase separation. Our analysis reveals that interaction sites within the IDR undergo dynamic rearrangement, driven by key residues that depend on the specific combination of folded domains. Upon RNA binding, several intermolecular interactions of TDP-43 are replaced by TDP-43-polyA interactions, altering viscoelastic properties of the condensate. Specifically, RRMs enhance viscosity, whereas the NTD reduces it. The presence of polyA increases elasticity, making viscosity and elasticity comparable in magnitude. These findings suggest that the multidomain structure of TDP-43 and its RNA interactions orchestrate condensate organization, modulating their viscoelastic properties.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph), Biomolecules (q-bio.BM)
Stainless steel in an electronically excited state
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Austenitic stainless steel (Fe$ _{0.5875}$ Cr$ _{0.25}$ Mn$ _{0.09}$ Ni$ _{0.07}$ C$ _{0.0025}$ ) is modeled with the XTANT-3 simulation toolkit to evaluate its properties in an electronically excited state produced by ultrafast laser irradiation. The model relies on density-functional tight binding to obtain the electronic Hamiltonian, producing the electronic energy levels and wave functions. They are used to calculate the electron heat capacity, electron heat conductivity, and electron-phonon coupling parameter at the electronic temperatures up to 25,000 K. It is revealed that stainless steel nonthermally melts at sub-picosecond timescales at the deposited dose of ~1.4 eV/atom (the electronic temperature $ T_e \sim 10,000$ K): the atomic lattice disorders due to modifications of the interatomic potential induced by the excitation of electrons, even without electron-phonon coupling (Born-Oppenheimer approximation). Including the electron-phonon coupling (non-Born-Oppenheimer simulation) lowers the damage threshold dose to ~0.45 eV/atom, triggering atomic disorder at picosecond timescales via thermal melting, predicated on the atomic heating by electrons.
Materials Science (cond-mat.mtrl-sci)
Crystal field excitations in rattling clathrate CeBa$_7$Au$6$Si${40}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
Michelangelo Tagliavini, Federico Mazza, Xinlin Yan, Andrey Sidorenko, Kevin Ackermann, Andrey Prokofiev, Kurt Kummer, Silke Paschen, Maurits W. Haverkort
We investigate the local crystal-field environment of cerium in the clathrate compound CeBa$ _7$ Au$ _6$ Si$ _{40}$ (Ce-BAS) using resonant inelastic x-ray scattering (RIXS) and magnetic susceptibility measurements. Ce-BAS is a rare example of a system where heavy-fermion physics coexists with low-energy rattling phonon modes, making it a candidate for enhanced thermoelectric performance. Magnetic susceptibility measurements reveal a temperature-dependent local moment that cannot be explained within a static crystal-field model. A fit to the susceptibility data requires strong mixing between the j = 5/2 and j = 7/2 crystal-field states, which implies large internal splittings inconsistent with RIXS spectra. In contrast, RIXS data are well described by a model with negligible j = 5/2 - j = 7/2 mixing and an energy separation of 12 meV between the ground and first excited crystal-field states. The inability to reconcile these two datasets within a static framework points to a dynamical modification of the crystal-field potential. We attribute this to coupling between the Ce 4f electrons and low-energy phonons associated with the Ce rattling motion. This interpretation is consistent with theoretical predictions of phonon-enhanced Kondo effects and dynamical Jahn-Teller distortions. Our results highlight the need for multi-orbital impurity models that include phonon coupling to fully describe the low-energy physics of Ce-BAS.
Strongly Correlated Electrons (cond-mat.str-el)
Unconventional Relaxation Dynamics in Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4: Evidence of Inertial Effects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
P. Saha, M. Singh, P. D. Babu, S. Patnaik
Magnetization relaxation dynamics serve as an essential tool for uncovering the intrinsic mechanisms governing the magnetic response and energy dissipation in magnetic systems. In this work, we examine the relaxation dynamics for Beta Mn type Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4 across a frequency range of 1 kHz to 10 kHz, spanning different magnetic phases. While most magnetic systems tend to follow the Debye-like relaxation with non-zero distribution or the Cole-Cole formalism, our analysis reveal that these conventional models fail to capture frequency dependence of ac susceptibility across different magnetic phases in Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4. Instead, an inertial component is needed to successfully describe the dynamics, suggesting the presence of unconventional relaxation behavior. The characteristic relaxation time is found to be of the order of 10^-5 s for both the compositions. The field dependent variation of relaxation time exhibits a non-monotonic nature, with the double peak like structure at the skyrmion phase transitions, implying slower relaxation dynamics at the phase boundaries. Furthermore, the presence of non-zero difference between isothermal and adiabatic susceptibility in the pure phases implies slower relaxation dynamics, which is consistent with the presence of finite dissipation in pure phases. The inertial term has been previously invoked to describe the dynamics in spin ice systems due to the propagation of magnetic monopoles. However, its necessity in this system, points to a wider significance in magnetization dynamics that goes beyond the conventional spin ices and skyrmions.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Creation and Microscopic Origins of Single-Photon Emitters in Transition Metal Dichalcogenides and Hexagonal Boron Nitride
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Amedeo Carbone, Diane-Pernille Bendixen-Fernex de Mongex, Arkady V. Krasheninnikov, Martijn Wubs, Alexander Huck, Thomas W. Hansen, Alexander W. Holleitner, Nicolas Stenger, Christoph Kastl
We highlight recent advances in the controlled creation of single-photon emitters in van der Waals materials and in the understanding of their atomistic origin. We focus on quantum emitters created in monolayer transition-metal dichalcogenide semiconductors, which provide spectrally sharp single-photon emission at cryogenic temperatures, and the ones in insulating hBN, which provide bright and stable single-photon emission up to room temperature. After introducing the different classes of quantum emitters in terms of band-structure properties, we review the defect creation methods based on electron and ion irradiation as well as local strain engineering and plasma treatments. A main focus of the review is put on discussing the microscopic origin of the quantum emitters as revealed by various experimental platforms, including optical and scanning probe methods.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Finite temperature phase diagram of the extended Bose-Hubbard model in the presence of disorder
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-29 20:00 EDT
Madhumita Kabiraj, Raka Dasgupta
We study the finite- and non-zero temperature phase diagram of the Extended Bose-Hubbard Model for both pure and disordered systems. Such a system can be experimentally realized by trapping ultracold Rydberg atoms in optical lattices. By regulating the Rydberg excitation level and the lattice spacing, the system can be engineered to effectively have (i) only the nearest-neighbor interaction and (ii) both nearest-neighbor and next-nearest-neighbor interactions. For both of these situations, we construct the mean-field phase diagrams. It is found that the presence of a non-zero temperature significantly changes the phase diagram because now there is a competition between quantum and thermal fluctuations. We observe that conventional Mott insulator (MI) or charge-density-wave (CDW) lobes vanish at higher temperatures. In a pure system, they melt into a normal fluid. In contrast, the only insulating phase that survives at high temperatures in the presence of disorder is a Bose glass. It is evident that the CDW lobes melt at a lower temperature and the Mott lobes melt at higher temperatures. These transition temperatures depend on the on-site and nearest-neighbor interaction strengths, respectively. It is also found that, with the addition of disorder, the insulating lobes are destroyed at a relatively lower temperature. The mathematical framework that we present here is capable of treating long-range interactions, disorder, and finite temperature simultaneously, and versatile enough so that it can be extended to study different forms of disorder or longer-range interactions.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Tunable Topological Superconductivity by Fully Compensated Ferrimagnets
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Yu-Xuan Li, Yicheng Liu, Cheng-Cheng Liu
We propose a platform based on a fully compensated ferrimagnet (fFIM) for realizing and controlling topological superconductivity with Majorana bound states across multiple dimensions. Through symmetry analysis and microscopic modeling, we demonstrate that fFIM-based heterostructures host (i) Majorana zero modes localized at the ends of one-dimensional nanowires, (ii) chiral Majorana edge states along two-dimensional boundaries, and (iii) tunable Majorana corner modes in higher-order topological phases. The unique properties of fFIMs enable an electric field to drive topological superconductivity phase transitions and Néel vector orientation to control the spatial distribution of Majorana modes, without external magnetic fields. Crucially, the absence of net magnetization in fFIM-based heterostructures preserves superconductivity, circumventing the usual trade-off between tunability and superconducting coherence in magnetized systems. Our results establish fFIM-based heterostructures as a versatile platform for tunable topological superconductivity.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Anisotropic supercurrent suppression and revivals in a graphene-based Josephson junction under in-plane magnetic fields
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-29 20:00 EDT
Philipp Schmidt, Katarina Stanojević, Kenji Watanabe, Takashi Taniguchi, Bernd Beschoten, Vincent Mourik, Christoph Stampfer
We report on a tunable Josephson junction formed by a bilayer graphene ribbon encapsulated in WSe$ _2$ with superconducting niobium contacts. We characterize the junction by measurements of the magnetic field induced interference pattern, and the AC Josephson effect manifested as “Shapiro steps”, examining current dependent hysteresis and junction dynamics. The latter can be tuned by temperature, gate voltage, and magnetic field. Finally, we examine the evolution of the supercurrent when subjected to in-plane magnetic fields. Notably, we observe a strong anisotropy in the supercurrent with respect to the orientation of the in-plane magnetic field. When the field is parallel to the current direction, the supercurrent is suppressed, and shows revivals with increasing magnetic field, whereas it remains almost unaffected when the field is oriented in a perpendicular direction. We suggest that this anisotropy is caused by the dependence of supercurrent interference on the junction geometry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Infinite temperature transport in the strong coupling regime of a nonintegrable quantum spin chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
We study spin transport of the XXZ model with next-nearest neighbor $ \Delta_2$ terms. We compute numerically dependence of spin conductivity $ \sigma(\omega)$ on the anisotropy $ \Delta$ and the ratio $ r= \Delta_2/\Delta$ , in the large $ \Delta$ regime. We find that, when $ 0<r<1$ , the low-frequency conductivity assumes an anomalous form $ \sigma(\omega)\approx a \omega^2 + b \Delta^{-2} $ . In particular, when $ \Delta\to\infty$ the model becomes dynamically constrained and most states are localized. We show, microscopically, existence of magnon bound states in the strong coupling regime, which behave as self-generated disorders for single magnons. Based on this quasiparticle picture, we obtain analytical scalings, which match well with the numerical results.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 7 figures
Dissipative particle dynamics models of encapsulated microbubbles and gas vesicles for biomedical ultrasound simulations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Nikolaos Ntarakas, Maša Lah, Daniel Svenšek, Tilen Potisk, Matej Praprotnik
Ultrasound-guided drug and gene delivery (usdg) enables controlled and spatially precise delivery of drugs and macromolecules, encapsulated in microbubbles (embs) and submicron gas vesicles (gvs), to target areas such as cancer tumors. It is a non-invasive, high precision, low toxicity process with drastically reduced drug dosage. Rheological and acoustic properties of gvs and embs critically affect the outcome of usdg and imaging. Detailed understanding and modeling of their physical properties is thus essential for ultrasound-mediated therapeutic applications. State-of-the-art continuuum models of shelled bodies cannot incorporate critical details such as varying thickness of the encapsulating shell or specific interactions between its constituents and interior or exterior solvents. Such modeling approaches also do not allow for detailed modeling of chemical surface functionalizations, which are crucial for tuning the gv-blood interactions. We develop a general particle-based modeling framework for encapsulated bodies that accurately captures elastic and rheological properties of gvs and embs. We use dissipative particle dynamics to model the solvent, the gaseous phase in the capsid, and the triangulated surfaces of immersed objects. Their elastic behavior is studied and validated through stretching and buckling simulations, eigenmode analysis, shear flow simulations, and comparison of predicted gv buckling pressure with experimental data from the literature. The presented modeling approach paves the way for large-scale simulations of encapsulated bodies, capturing their dynamics, interactions, and collective behavior.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Computational Physics (physics.comp-ph)
55 pages, 18 figures, 4 tables
Epitaxial growth of BaBiO3 thin films on SrTiO3(001) and MgO(001) substrates using molecular beam epitaxy and controlling their crystal orientations competition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Islam Ahmed, Stefan De Gendt, Clement Merckling
BaBiO3 has lately gained high research attention as a parent material for an interesting family of alloyed compositions with multiple technological applications. In order to grow a variety of structures, a versatile deposition tool such as molecular beam epitaxy has to be employed. In this work, molecular beam epitaxy growth of BaBiO3 on SrTiO3(001) and MgO(001) substrates is studied. When grown by molecular beam epitaxy on SrTiO3(001) or MgO(001) substrates, BaBiO3 is known to have two competing orientations namely, (001) and (011). Characterization of the thin film is carried out by X-ray diffraction, X-ray reflectivity, atomic force microscopy, Rutherford backscattering, and transmission electron microscopy. Pathways to block the growth of BaBiO3(011) and only grow the technologically relevant BaBiO3(001) are described for both substrates. Understanding of the enabler mechanism of the co-growth is established from epitaxy point of view. This can be beneficially utilized for growth of the different compositions of BaBiO3 material family in a more controlled manner.
Materials Science (cond-mat.mtrl-sci)
Post-buckling of fiber-reinforced soft tissues
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-29 20:00 EDT
Yang Liu, Rui-Cheng Liu, Wanyu Ma, Alain Goriely
Fiber-reinforcement is a universal feature of many biological tissues. It involves the interplay between fiber stiffness, fiber orientation, and the elastic properties of the matrix, influencing pattern formation and evolution in layered tissues. Here, we investigate the deformation of a compressed film bonded to a half-space, where either the film or the substrate exhibits anisotropy. Within the framework of finite elasticity, we formulate nonlinear incremental equations, enabling linear and weakly nonlinear analyses. These analyses yield exact bifurcation conditions and an amplitude equation for surface wrinkling. In particular, for a simple fiber-reinforced model, we show that the bifurcation can be supercritical or subcritical depending on the ratio between the substrate and the film moduli. These findings underscore the pivotal role of fiber-reinforcement in shaping pattern formation in anisotropic tissues and provide insights into the morphological evolution of biological tissues.
Soft Condensed Matter (cond-mat.soft)
37 pages, 17 figures
Ultrafast Electronic Structure Engineering in 1$T$-TaS$_2$: Role of Doping and Amplitude Mode Dynamics
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
J. Jayabalan, Jiyu Chen, Laura Pätzold, Francesco Petocchi, Florian K. Diekmann, Negar Najafianpour, Ping Zhou, Walter Schnelle, Gesa-R. Siemann, Philip Hofmann, Kai Roßnagel, Tim Wehling, Martin Eckstein, Philipp Werner, Uwe Bovensiepen
In strongly correlated transition metal dichalcogenides, an intricate interplay of polaronic distortions, stacking arrangement, and electronic correlations determines the nature of the insulating state. Here, we study the response of the electronic structure to optical excitations to reveal the effect of chemical electron doping on this complex interplay. Transient changes in pristine and electron-doped 1$ T$ -TaS$ _2$ are measured by femtosecond time-resolved photoelectron spectroscopy and compared to theoretical modeling based on non-equilibrium dynamical mean-field theory and density functional theory. The fine changes in the oscillatory signal of the charge density wave amplitude mode indicate phase-dependent modifications in the Coulomb interaction and the hopping. Furthermore, we find an enhanced fraction of monolayers in the doped system. Our work demonstrates how the combination of time-resolved spectroscopy and advanced theoretical modeling provides insights into the physics of correlated transition metal dichalcogenides.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 5 figures
Graph Neural Network Prediction of Nonlinear Optical Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Yomn Alkabakibi, Congwei Xie, Artem R. Oganov
Nonlinear optical (NLO) materials for generating lasers via second harmonic generation (SHG) are highly sought in today’s technology. However, discovering novel materials with considerable SHG is challenging due to the time-consuming and costly nature of both experimental methods and first-principles calculations. In this study, we present a deep learning approach using the Atomistic Line Graph Neural Network (ALIGNN) to predict NLO properties. Sourcing data from the Novel Opto-Electronic Materials Discovery (NOEMD) database and using the Kurtz-Perry (KP) coefficient as the key target, we developed a robust model capable of accurately estimating nonlinear optical responses. Our results demonstrate that the model achieves 82.5% accuracy at a tolerated absolute error up to 1 pm/V and relative error not exceeding 0.5. This work highlights the potential of deep learning in accelerating the discovery and design of advanced optical materials with desired properties.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Optics (physics.optics)
7 pages, 2 figures, 2 tables
Curiosity Driven Exploration to Optimize Structure-Property Learning in Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Aditya Vatsavai, Ganesh Narasimha, Yongtao Liu, Jan-Chi Yang, Hiroshu Funakubo, Maxim Ziatdinov, Rama Vasudevan
Rapidly determining structure-property correlations in materials is an important challenge in better understanding fundamental mechanisms and greatly assists in materials design. In microscopy, imaging data provides a direct measurement of the local structure, while spectroscopic measurements provide relevant functional property information. Deep kernel active learning approaches have been utilized to rapidly map local structure to functional properties in microscopy experiments, but are computationally expensive for multi-dimensional and correlated output spaces. Here, we present an alternative lightweight curiosity algorithm which actively samples regions with unexplored structure-property relations, utilizing a deep-learning based surrogate model for error prediction. We show that the algorithm outperforms random sampling for predicting properties from structures, and provides a convenient tool for efficient mapping of structure-property relationships in materials science.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
12 pages, 8 figures
Exploring two dimensional $\mathbb{Z}_2$ invariant phases with time reversal symmetry and their transitions with topological operations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-29 20:00 EDT
We use various topological operations to systematically study phase transitions between theories with $ \mathbb{Z}_2$ and time reversal symmetry in two spacetime dimensions. The phases (and accompanying CFTs) we consider come in two types - bosonic phases that are defined on unorientable manifolds and fermionic phases that are sensitive to a $ \text{Pin}^-$ structure. In both cases, our analysis leads to eight phase diagrams, with the two sets of eight connected by fermionization/bosonization. Starting from a seed CFT, we obtain the CFT that governs each transition. Many of these exhibit symmetry enriched criticality. In addition to showing many symmetry enriched CFTs in their natural habitats, our work discusses the fermionic analogs of the $ \mathbb{Z}_2$ bosonic operations, which we have not seen discussed in the literature.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
Textured growth and electrical characterization of Zinc Sulfide on back-end-of-the-line (BEOL) compatible substrates
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-29 20:00 EDT
Claire Wu, Mythili Surendran, Anika Tabassum Priyoti, Gokul Anilkumar, Cheng-Hsien Wu, Chun-Chen Wang, Cheng-Chen Kuo, Harish Kumasubramanian, Kenta Lin, Amari Butler, Rehan Kapadia, Xinyu Bao, Jayakanth Ravichandran
Scaling of transistors has enabled continuous improvements in logic device performance, especially through materials engineering. However, surpassing horizontal limitations in chip manufacturing requires a vertical, third dimension. Three-dimensional integration of high-performance logic demands solving the challenge of low-temperature (less than 450°C) synthesis of high-mobility n-type and p-type semiconductor thin films for back-end-of-line (BEOL) compatible transistors. Metal oxides, particularly indium oxides alloyed with gallium and tungsten, are promising n-type channel materials, but suitable p-type materials for BEOL remain scarce. Zinc sulfide (ZnS), a wide band-gap semiconductor, shows room-temperature p-type conductivity when doped with copper and crystallizes below 400°C. Here, we report growth of crystalline ZnS thin films by pulsed laser deposition on amorphous and polycrystalline surfaces including silicon nitride, thermal silicon dioxide, yttrium oxide, hafnium dioxide, sapphire, platinum, and titanium nitride. X-ray diffraction reveals out-of-plane texturing across all surfaces, while grazing incidence wide-angle X-ray scattering probes in-plane crystalline quality. Surface and interface properties are assessed using X-ray reflectivity and atomic force microscopy. Electrical characterization via J-V measurements (ZnS on Pt) and metal-oxide-semiconductor capacitor (ZnS on silicon dioxide) measurements show low leakage current ($ 10^{-5} A/cm^2$ at 0.40 MV/cm) and bilayer capacitor behavior, suggesting ZnS is highly intrinsic with minimal electrically active defects. Further work on doping ZnS with copper or other p-type elements is needed to realize ZnS as a dopable wide band-gap semiconductor for BEOL integration. This work demonstrates a novel thin-film growth method for sulfide semiconductors under BEOL-compatible conditions.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Towards Scalable Braiding: Topological Superconductivity Unlocked under Nearly Arbitrary Magnetic Field Directions in Planar Josephson Junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-29 20:00 EDT
Richang Huang, Yongliang Hu, Xianzhang Chen, Peng Yu, Igor Zutic, Tong Zhou
Majorana zero modes (MZM), distinguished by their non-locality and non-Abelian statistics, are central to the pursuit of fault-tolerant topological quantum computing. Planar Josephson junctions (PJJ) have emerged as a promising platform, offering robust and tunable MZM. However, the perceived sensitivity of topological superconductivity to the magnetic field orientation has posed a major obstacle, particularly for scalable network architectures. Here, we uncover that topological superconductivity in PJJ fundamentally persists under nearly arbitrary in-plane magnetic field directions. The apparent collapse of the global gap under misaligned fields originates not from the destruction of superconductivity itself, but from emergent shifted bulk states from other momentum points, which obscure the gap and MZM. By introducing spatial modulations along the junction to scatter and gap out these bulk states, we restore the global topological gap and recover visible MZM. Remarkably, the spatially modulated PJJs render topological superconductivity robust against maligned fields, thereby enabling MZM survival across complex junction networks and facilitating their braiding. We propose a scalable protocol for MZM braiding and fusion with phase or gate control, opening new routes toward scalable topological quantum computing.
Superconductivity (cond-mat.supr-con)
6 pages and 4 figures