CMP Journal 2025-05-15
Statistics
Nature: 1
Nature Materials: 1
Nature Nanotechnology: 2
Physical Review Letters: 7
Physical Review X: 2
Review of Modern Physics: 1
arXiv: 65
Nature
Ku limits RNA-induced innate immunity to allow Alu-expansion in primates
Original Paper | Genomic instability | 2025-05-14 20:00 EDT
Yimeng Zhu, Angelina Li, Suvrajit Maji, Brian J. Lee, Sophie M. Korn, Jake A. Gertie, Tyler J. Dorrity, Jianhua Wang, Kyle J. Wang, Amandine Pelletier, Daniel F. Moakley, Rachel D. Kelly, Antony B. Holmes, Raul Rabadan, David R. Edgell, Caroline Schild Poulter, Mauro Modesti, Anna-Lena Steckelberg, Eric A. Hendrickson, Hachung Chung, Chaolin Zhang, Shan Zha
Ku70 and Ku80 form Ku, a ring-shaped complex that initiates the non-homologous end-joining (NHEJ) DNA repair pathway.1 Ku binds to double-stranded DNA (dsDNA) ends and recruits other NHEJ factors (e.g., LIG4, DNA-PKcs). While Ku can bind to double-stranded RNA (dsRNA)2 and trap mutated-DNA-PKcs on ribosomal RNA (rRNA),3,4 the physiological role on Ku-RNA interaction in otherwise wildtype cells remains unclear. Intriguingly, Ku is dispensable for murine development5,6 but essential in human cells.7 Despite similar genome sizes, human cells express 100-fold more Ku than mouse cells, implying functions beyond NHEJ - possibly through a dose-sensitive interaction with dsRNA, which binds Ku 10100 times weaker than dsDNA.2,8 Investigating Ku’s essentiality in human cells, we found that Ku-depletion - unlike LIG4 - induces profound interferon (IFN) and NF-kB signaling via dsRNA-sensor MDA5/RIG-I and MAVS. Prolonged Ku-degradation further activates other dsRNA sensors, especially PKR (suppressing translation) and OAS/RNaseL (cleaving rRNA), leading to growth arrest and cell death. MAVS, RIG-I, or MDA5 knockouts suppressed IFN signaling and, like PKR knockouts, all partially rescued Ku-depleted human cells. Ku-irCLIP analyses revealed Ku binding to diverse dsRNA, predominantly stem-loops in primate-specific antisense Alu elements9 in introns and 3’-UTRs. Ku expression rose sharply in higher primates, correlating tightly with Alu-expansion (r = 0.94/0.95). Thus, Ku plays a vital role in accommodating Alu-expansion in primates by limiting dsRNA-induced innate immunity, explaining both Ku’s elevated expression and its essentiality in human cells.
Genomic instability, Innate immunity, Molecular evolution
Nature Materials
Polariton probing of attometre displacement and nanoscale strain in ultrashort acoustic pulses
Original Paper | Imaging and sensing | 2025-05-14 20:00 EDT
Marek Karzel, Anton K. Samusev, Tetiana L. Linnik, Mario Littmann, Dirk Reuter, Manfred Bayer, Andrey V. Akimov, Alexey V. Scherbakov
Atomic displacement and lattice strain are inextricably linked to most ultrafast processes in solids, such as optically induced phase transitions or demagnetization. Visualizing lattice dynamics, which is typically done using time-resolved X-ray and electron diffraction techniques, yields information about the physical processes involved. However, the detection of atomic motion of an amplitude much less than a picometre has remained challenging. For this purpose, we suggest exploiting the acoustic pulse generated by a spatially localized ultrafast process in the surrounding volume. Its optical detection in a material possessing a narrow polariton resonance provides superior sensitivity. In the validating experiment, we detect the acoustic pulse generated by a 100 attometre thermal expansion of a 100 nanometre metallic film heated with a temperature increase of 0.2 kelvin by a femtosecond optical pulse. Even though the generated acoustic pulse carries dynamical strain with a magnitude of only 10-9, being injected into the polaritonic layer, it can be confidently detected through transient reflectivity.
Imaging and sensing, Optomechanics, Semiconductors, Ultrafast photonics
Nature Nanotechnology
Discovering nanoparticle corona ligands for liver macrophage capture
Original Paper | Biomedical engineering | 2025-05-14 20:00 EDT
Bram Bussin, Marshall G. G. MacDuff, Wayne Ngo, Jamie L. Y. Wu, Zachary P. Lin, Adrian Granda Farias, Benjamin Stordy, Zahra Sepahi, Sara Ahmed, Jason Moffat, Warren C. W. Chan
Liver macrophages capture circulating nanoparticles and reduce their delivery to target organs. Serum proteins adsorb to the nanoparticle surface after administration. However, the adsorbed serum proteins and their cognate cell receptors for removing nanoparticles from the bloodstream have not been linked. Here we use a multi-omics strategy to identify the adsorbed serum proteins binding to specific liver macrophage receptors. We discovered six absorbed serum proteins that bind to two liver macrophage receptors. Nanoparticle physicochemical properties can affect the degree of the six serum proteins adsorbing to the surface, the probability of binding to cell receptors and whether the liver removes the nanoparticle from circulation. Identifying the six adsorbed proteins allowed us to engineer decoy nanoparticles that prime the liver to take up fewer therapeutic nanoparticles, enabling more nanoparticles for targeting extrahepatic tissues. Elucidating the molecular interactions governing the nanoparticle journey in vivo will enable us to control nanoparticle delivery to diseased tissues.
Biomedical engineering, Drug delivery
Analysis of multi-drug cancer nanomedicine
Original Paper | Drug delivery | 2025-05-14 20:00 EDT
Karina Benderski, Twan Lammers, Alexandros Marios Sofias
Multi-drug nanomedicine is gaining momentum for co-delivering more than one drug to the same site at the same time. Our analysis of 273 pre-clinical tumour growth inhibition studies shows that multi-drug nanotherapy outperforms single-drug therapy, multi-drug combination therapy, and single-drug nanotherapy by 43, 29 and 30%, respectively. Combination nanotherapy also results in the best overall survival rates, with 56% of studies demonstrating complete or partial survival, versus 20-37% for control regimens. Within the multi-drug nanomedicine groups, we analysed the effect of (co-)administration schedule and strategy, passive versus active targeting, nanocarrier material and the type of therapeutic agent. Most importantly, it was found that co-encapsulating two different drugs in the same nanoformulation reduces tumour growth by a further 19% compared with the combination of two individually encapsulated nanomedicines. We finally show that the benefit of multi-drug nanotherapy is consistently observed across different cancer types, in sensitive and resistant tumours, and in xenograft and allograft models. Altogether, this meta-analysis substantiates the value of multi-drug nanomedicine as a potent strategy to improve cancer therapy.
Drug delivery, Nanoparticles
Physical Review Letters
Universal Quantum Computer From Relativistic Motion
Research article | Artificial intelligence | 2025-05-14 06:00 EDT
Philip A. LeMaitre, T. Rick Perche, Marius Krumm, and Hans J. Briegel
We present an explicit construction of a relativistic quantum computing architecture using a variational quantum circuit approach that is shown to allow for universal quantum computing. The variational quantum circuit consists of tunable single-qubit rotations and entangling gates that are implemented successively. The single-qubit rotations are parameterized by the proper time intervals of the qubits’ trajectories and can be tuned by varying their relativistic motion in spacetime. The entangling layer is mediated by a relativistic quantum field instead of through direct coupling between the qubits. Within this setting, we give a prescription for how to use quantum field-mediated entanglement and manipulation of the relativistic motion of qubits to obtain a universal gate set, for which compact nonperturbative expressions that are valid for general spacetimes are also obtained. We also derive a lower bound on the channel fidelity that shows the existence of parameter regimes in which all entangling operations are effectively unitary, despite the noise generated from the presence of a mediating quantum field. Finally, we consider an explicit implementation of the quantum Fourier transform with relativistic qubits.
Phys. Rev. Lett. 134, 190601 (2025)
Artificial intelligence, Quantum algorithms & computation, Quantum circuits, Quantum entanglement, Quantum field theory (low energy), Quantum information theory, Relativistic quantum information
Cold Dark Matter Based on an Analogy with Superconductivity
Research article | Dark energy | 2025-05-14 06:00 EDT
Guanming Liang (梁冠铭) and Robert R. Caldwell
Drawing on an analogy with superconductivity, theorists have proposed a dark matter candidate that could have left observable signatures in the cosmic microwave background.
Phys. Rev. Lett. 134, 191004 (2025)
Dark energy, Dark matter, Particle dark matter, BCS theory
Nonreciprocal Interactions Induce Frequency Shifts in Superradiant Lasers
Research article | Collective effects in atomic physics | 2025-05-14 06:00 EDT
Tobias Nadolny, Matteo Brunelli, and Christoph Bruder
Superradiant lasers, which consist of incoherently driven atoms coupled to a lossy cavity, are a promising source of coherent light due to their stable frequency and superior narrow linewidth. We show that when a fraction of the atoms is not driven, a shift in the lasing frequency and a broadening of the linewidth occur, limiting the performance of a superradiant laser. We explain this behavior by identifying nonreciprocal interactions between driven and undriven atoms, i.e., competing alignment and antialignment of their dipoles. Our results have implications for the realization of superradiant lasers, establishing the relevance of nonreciprocal phenomena for quantum technologies.
Phys. Rev. Lett. 134, 193603 (2025)
Collective effects in atomic physics, Lasers, Open quantum systems, Pattern formation, Superradiance & subradiance, Time crystals, Collective dynamics, Theories of collective dynamics & active matter
Nonlinear Semiclassical Spectroscopy of Ultrafast Molecular Polariton Dynamics
Research article | Cavity quantum electrodynamics | 2025-05-14 06:00 EDT
Michael Reitz, Arghadip Koner, and Joel Yuen-Zhou
We introduce a theoretical framework that allows for the systematic and efficient description of the ultrafast nonlinear response of molecular polaritons, i.e., hybrid light-matter states, in the collective regime of large numbers of molecules $\mathcal{N}$ coupled to the cavity photon mode. Our approach is based on a semiclassical, mean-field evolution of the molecular Hamiltonian and the cavity field, which is complemented by a perturbative expansion of both light and matter counterparts in the input fields entering the cavity. In addition, expansion in terms of the pulse phases enables us to disentangle different excitation pathways in Liouville space, thereby distinguishing contributions to the nonlinear response. The formalism extends traditional free-space nonlinear spectroscopy by incorporating the feedback of matter onto the light field via the induced polarization. We demonstrate the utility of the framework by applying it to the calculation of pump-probe polariton spectra and show how, by storing the pulses, the cavity facilitates additional excitation pathways, which can be used to isolate purely bright state contributions. Our method, which does not scale with $\mathcal{N}$, is broadly applicable and can be extended to model a wide range of current experiments investigating the dynamical nonlinear response of hybrid light-matter states.
Phys. Rev. Lett. 134, 193803 (2025)
Cavity quantum electrodynamics, Light-matter interaction, Nonlinear optics, Polaritons, Ultrafast phenomena, Molecules, Organic microcavities, Polarization, Dicke model, Dipole approximation, Perturbative methods, Semiclassical methods
Intertwined Superconductivity and Orbital Selectivity in a Three-Orbital Hubbard Model for the Iron Pnictides
Research article | High-temperature superconductors | 2025-05-14 06:00 EDT
Vito Marino, Alberto Scazzola, Federico Becca, Massimo Capone, and Luca F. Tocchio
We study a three-orbital Hubbard-Kanamori model relevant for iron-based superconductors using variational wave functions explicitly including spatial correlations and electron pairing. We span the nonmagnetic sector from filling $n=4$, which is representative of undoped iron-based superconductors, to $n=3$, where a Mott insulating state with each orbital at half filling is found. In the strong-coupling regime, when the electron density is increased, we find a spontaneous differentiation between the occupation of ${d}{xz}$ and ${d}{yz}$ orbitals, leading to an orbital-selective state with a nematic character that becomes stronger at increasing density. One of these orbitals stays half filled for all densities while the other one hosts (together with the ${d}_{xy}$ orbital) the excess of electron density. Most importantly, in this regime long-range pairing correlations appear in the orbital with the largest occupation. Our results highlight a strong link between orbital-selective correlations, nematicity, and superconductivity, which requires the presence of a significant Hund’s coupling.
Phys. Rev. Lett. 134, 196502 (2025)
High-temperature superconductors, Iron-based superconductors, Strongly correlated systems, Dynamical mean field theory, Hubbard model, Monte Carlo methods
Electrically Tunable Interband Collective Excitations in Biased Bilayer and Trilayer Graphene
Research article | Excitons | 2025-05-14 06:00 EDT
Tomer Eini, M. F. C. Martins Quintela, J. C. G. Henriques, R. M. Ribeiro, Yarden Mazor, N. M. R. Peres, and Itai Epstein
Collective excitations of charged particles under the influence of an electromagnetic field give rise to a rich variety of hybrid light-matter quasiparticles with unique properties. In metals, intraband collective response manifested by negative permittivity leads to plasmon polaritons with extreme field confinement, wavelength ‘’squeezing,’’ and potentially low propagation losses. In contrast, photons in semiconductors commonly couple to interband collective response in the form of exciton polaritons, which give rise to completely different polaritonic properties, described by a superposition of the photon and exciton and an anti-crossing of the eigenstates. In this work, we identify the existence of plasmon-like collective excitations originating from the interband excitonic response of biased bilayer and trilayer graphene, in the form of graphene exciton polaritons (GEPs). We find that GEPs possess electrically tunable polaritonic properties and discover that such excitations follow a universal dispersion law for all surface polaritons in 2D excitonic systems. Accounting for nonlocal corrections to the excitonic response, we find that the GEPs exhibit confinement factors that can exceed those of graphene plasmons, and with moderate losses that would enable their observation in cryo-SNOM experiments. These predictions of plasmon-like interband collective excitations in biased graphene systems open up new research avenues for tunable plasmonic phenomena based on excitonic systems, and the ability to control and manipulate such phenomena at the atomic scale.
Phys. Rev. Lett. 134, 196903 (2025)
Excitons, Plasmons, Polaritons, Quasiparticles & collective excitations, Surface plasmons, Graphene
Nonreciprocal Control of the Speed of Light Using Cavity Magnonics
Research article | Electromagnetically induced transparency | 2025-05-14 06:00 EDT
Jiguang Yao, Chenyang Lu, Xiaolong Fan, Desheng Xue, Greg E. Bridges, and C.-M. Hu
Researchers have demonstrated the direction-dependent slowdown of microwave pulses, with potential applications in signal processing and quantum computing.
Phys. Rev. Lett. 134, 196904 (2025)
Electromagnetically induced transparency, Light-matter interaction, Magnetization dynamics, Optical & microwave phenomena, Polaritons, Coupled oscillators, Devices for digital logic, storage & processing, Non-Hermitian systems, Cavity resonators, Coupled mode theory, Electromagnetic wave theory, Ferromagnetic resonance
Physical Review X
Directional Pumping of Coherent Phonons and Quasiparticle Renormalization in a Dirac Nodal-Line Semimetal
Research article | Coherent control | 2025-05-14 06:00 EDT
Chenyu Wang, Daqiang Chen, Yaxian Wang, and Sheng Meng
Tuning a laser’s frequency flips the phase of coherent phonons in a topological semimetal, enabling precise control of vibrations and offering a new way to manipulate material properties.
Phys. Rev. X 15, 021053 (2025)
Coherent control, Electron-phonon coupling, Electronic structure, Lattice dynamics, Ultrafast phenomena, Node-line semimetals, Time-dependent DFT
Topological Flat-Band-Driven Metallic Thermoelectricity
Research article | Density of states | 2025-05-14 06:00 EDT
Fabian Garmroudi, Jennifer Coulter, Illia Serhiienko, Simone Di Cataldo, Michael Parzer, Alexander Riss, Matthias Grasser, Simon Stockinger, Sergii Khmelevskyi, Kacper Pryga, Bartlomiej Wiendlocha, Karsten Held, Takao Mori, Ernst Bauer, Antoine Georges, and Andrej Pustogow
Kagome metals show promise for thermoelectrics, thanks to an interplay between flat and dispersive bands that boosts their thermoelectric response.
Phys. Rev. X 15, 021054 (2025)
Density of states, Electrical conductivity, Electrical properties, Electronic structure, Energy conversion technologies, Energy harvesting devices, Energy materials, Fermi surface, First-principles calculations, Flat bands, Thermoelectrics, Topological materials
Review of Modern Physics
Colloquium: Materials that exceed classical thermodynamic bounds on properties
Research article | | 2025-05-14 06:00 EDT
Roderic S. Lakes
Classical thermodynamic bounds provide constraints on values that are expected in measurements of certain physical properties. In a variety of fields, some measurements exceed these bounds. This apparent violation of thermodynamics arises because the measurements are made in ways that violate the underlying assumptions made when deriving these bounds. This Colloquium describes a wide variety of circumstances where such violations occur and which of the underlying assumptions are violated in each case. It also describes how interesting material properties can be developed using materials designed to violate these assumptions.
Rev. Mod. Phys. 97, 021002 (2025)
arXiv
How to Incorporate External Fields in Analog Ising Machines
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
Robbe De Prins, Jacob Lamers, Peter Bienstman, Guy Van der Sande, Guy Verschaffelt, Thomas Van Vaerenbergh
Ising machines (IMs) are specialized devices designed to efficiently solve combinatorial optimization problems (COPs). They consist of artificial spins that evolve towards a low-energy configuration representing a problem’s solution. Most realistic COPs require both spin-spin couplings and external fields. In IMs with analog spins, these interactions scale differently with the continuous spin amplitudes, leading to imbalances that affect performance. Various techniques have been proposed to mitigate this issue, but their performance has not been benchmarked. We address this gap through a numerical analysis. We evaluate the time-to-solution of these methods across three distinct problem classes with up to 500 spins. Our results show that the most effective way to incorporate external fields is through an approach where the spin interactions are proportional to the spin signs, rather than their continuous amplitudes.
Statistical Mechanics (cond-mat.stat-mech), Emerging Technologies (cs.ET), Quantum Physics (quant-ph)
30 pages, 17 figures, and 2 tables, including Supplementary Material. The first two authors contributed equally
Estimation of oil recovery due to wettability changes in carbonate reservoirs
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
A.C. Alvarez, H. Bruining, D. Marchesin
Low salinity waterflooding (LSWF) enhances oil recovery at low cost in carbonate reservoirs, but its effectiveness requires precise control of injected water chemistry and interaction with reservoir minerals. This study develops an integrated reactive transport model coupling geochemical surface complexation modeling (SCM) with multiphase compositional dynamics to quantify wettability alteration during LSWF. The framework combines PHREEQC-based equilibrium calculations of the Total Bond Product (TBP), a wettability indicator derived from oil-calcite ionic bridging, with Corey-type relative permeability interpolation, resolved via COMSOL Multiphysics. Core flooding simulations, compared with experimental data from calcite systems at 100 degrees Celsius and 220 bar, reveal that magnesium and sulfate concentrations modulate TBP, reducing oil-rock adhesion under controlled low-salinity conditions. Parametric analysis demonstrates that acidic crude oils (TAN higher than 1 mg KOH per gram) exhibit TBP values approximately 2.5 times higher than sweet crudes, due to carboxylate-calcite bridging, while pH elevation (above 7.5) amplifies wettability shifts by promoting deprotonated carboxyl interactions. The model further identifies synergistic effects between magnesium (50 to 200 millimoles per kilogram of water) and sulfate (above 500 millimoles per kilogram of water), which reduce calcium-mediated oil adhesion through competitive mineral surface binding. By correlating TBP with fractional flow dynamics, this framework could support the optimization of injection strategies in carbonate reservoirs, suggesting that ion-specific adjustments are more effective than bulk salinity reduction.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Higher-order Topological Parity Anomaly and Half-integer Hall Effect in High-dimensional Synthetic Lattices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Xian-Hao Wei, Xi-Wang Luo, Guang-Can Guo, Zheng-Wei Zhou
Recent advances in constructing synthetic dimension provide a powerful tool for exploring exotic topological states of matter in high dimensions. Here we report that the parity anomaly and associated \textit{half-integer} quantized Hall conductance, arising in 2$ j$ +1 (space-time) dimensions with a single or odd number of Dirac cones, can be realized by the boundary states of $ n$ -th order topological insulators in (2$ j$ +$ n$ )-dimensional synthetic lattices. We establish a general bulk-boundary correspondence by integrating the ``nested” Wilson loop theory with the time-reversal polarization at highly-symmetric momenta, a set of $ Z_2$ topological invariants are extracted which determines the number of higher-order-boundary Dirac cones and their locations. We develop a general construction procedure for Hamiltonians supporting such higher-order topological parity anomaly. Moreover, we propose an experimental implementation scheme based on photonic synthetic dimensions and provide a method for probing the associated half-integer Hall conductance by the transmission spectra. Our work offers the realization and characterization of parity anomaly in general high-dimensional higher-order topological insulators and opens an avenue for exploring fundamental physics and possible device applications enabled by manipulating Dirac cones.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Optics (physics.optics), Quantum Physics (quant-ph)
5 pages, 4 figures, with 15 page Supplementary information
The Two-Fluid Theory for Superfluid Hydrodynamics and the Fountain Pressure Paradox
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
The two-fluid theory for superfluid hydrodynamics is derived from the fountain pressure result that condensed bosons move at constant entropy, and that therefore steady superfluid flow connects regions of equal chemical potential. The paradox of the fountain pressure equation is resolved with a quantitative prediction.
Statistical Mechanics (cond-mat.stat-mech)
6 pages
Propagation of Spin Waves in Doubly Periodic Magnonic Crystals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Adam G. Whitney, Joshua M. Lewis, Justin Dickovick, Vijay Kalappattil, Lincoln D. Carr, Mingzhong Wu
Towards the development of strategies for tailoring spin-wave band gaps in magnonic crystals, this work examines the band gap properties in a one-dimensional magnonic crystal with double periodicity. A long and narrow yttrium iron garnet (YIG) thin film strip is etched with an array of transverse groove lines separated by alternating distances, where the second distance is twice the first. This double periodicity in the magnonic crystal translates into dissimilar band gaps in the frequency domain, with the third and sixth band gaps being more pronounced than others. These band gaps are more pronounced because the corresponding wavenumbers simultaneously satisfy the Bragg scattering conditions for the periods equal to the two groove separations as well as their sum. Experimental observations are reproduced by numerical simulations. Together, the experimental and numerical results demonstrate how multiple periodicities could be an effective design parameter for creating magnonic crystals with desired band gaps.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Majorana Edge Modes as Quantum Memory for Topological Quantum Computing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
We demonstrate that a combination of Majorana edge modes (MEMs) and Majorana zero modes (MZMs) located in the vortex cores of two-dimensional topological superconductors represent a new platform for the efficient implementation of fault-tolerant quantum gates. By calculating the full many-body dynamics of the system, we demonstrate the successful simulation and visualization of $ Z$ -, $ X$ - and Hadamard gates, with MEMs being functionalized as quantum memory. Our results open a new platform for the efficient implementation of fault-tolerant quantum computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Supplementary Material and Movies available upon request
Probing time-reversal symmetry breaking at microwave frequencies
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Motivated by experiments carried out in the near infrared using zero-loop-area Sagnac interferometers, we explore electromagnetic signatures of time-reversal symmetry breaking (TRSB) at microwave frequencies, using as a prototypical example a semiclassical conductor in a magnetic field. TRSB is generically accompanied by a skew-symmetric term in the electrodynamic response tensors (permittivity, conductivity, surface impedance), imparting a nonreciprocal phase shift to left- and right-circularly polarized electromagnetic waves reflected from the surface of such a material. We show that TRSB manifests as a difference in the surface reactance experienced by circularly polarized waves, and can be detected using a doubly degenerate resonator mode, such as the TE$ _{111}$ mode of a cylindrical cavity. In addition to the frequency splitting induced by TRSB we show that, when interrogated by circularly polarized microwaves, the forward and reverse transmission responses of such a resonator break reciprocity, providing a crucial signature that distinguishes true Faraday effects (i.e., circular birefringence) from non-TRSB effects such as linear birefringence. In the limit that the sample is larger than the spot size (i.e., larger than the diameter of the microwave cavity) we show that the TRSB resonator has sensitivity to polar Kerr angle comparable to that of the zero-loop-area Sagnac, and should provide complementary insights into unconventional superconductors such as UPt$ _3$ and Sr$ _2$ RuO$ _4$ that have been observed to spontaneously break time-reversal symmetry.
Superconductivity (cond-mat.supr-con)
12 pages, 6 figures
Epitaxial growth of gold films on the elemental superconductors V(100), Nb(100) and Nb(110)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Dongfei Wang, Katerina Vaxevani, Danilo Longo, Samuel Kerschbaumer, Jon Ortuzar, Stefano Trivini, Jingcheng Li, Maxim Ilyn, Celia Rogero, Jose Ignacio Pascual
Quantum technologies require a new generation of superconducting electronic devices and circuitry. However, the superconducting materials used to construct them are restricted to a class of bulk superconductors. Gold films grown in contact with superconducting materials can exhibit superconducting correlations through the proximity effect, with various possible implementations in quantum technology. Here, we study the growth of flat Au films on various surfaces of the elemental superconductors vanadium and niobium through a combination of low-temperature scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In particular, we investigate the growth morphology and composition as a function of temperature and coverage. We find that gold films can grow flat and oxygen-free when annealed to sufficiently high temperatures; however, they are also susceptible to partial intermixing with the substrate elements. Low-temperature scanning tunneling spectroscopy (STS) measurements elucidate the emergence of a proximitized superconducting gap at the gold surface. Additionally, we demonstrate the survival of the magnetic state of FeTPP-Cl molecules on the surface of these gold films, proving that they behave as a good support for probing molecular magnetism. We found that the exchange interaction between the molecular spin and the superconducting condensate can be inferred by the measurement of sub-gap Yu-Shiva-Rusinov states. Our work shows that proximitised Au films constitute a promising platform to explore on-superconducting-surface synthesis and the interaction between superconductivity and magnetism in a large spin-orbit coupling environment.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 7 figures
Physics-informed machine learning applied to the identification of high-pressure elusive phases from spatially resolved X-ray diffraction large datasets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Lucas H. Francisco, Camila M. Araújo, André A. M. C. Silva, Ulisses F. Kaneko, Jairo Fonseca Jr, Guilherme A. Calligaris, Audrey D. Grockowiak, Danusa do Carmo, Ricardo D. dos Reis, Narcizo M. Souza-Neto
Multi-technique high resolution X-ray mapping enhanced by the recent advent of 4th generation synchrotron facilities can produce colossal datasets, challenging traditional analysis methods. Such difficulty is clearly materialized when probing crystal structure of inhomogeneous samples, where the number of diffraction patterns quickly increases with map resolution, making the identification of crystal phases within a vast collection of reflections unfeasibly challenging by direct human inspection. Here we develop a novel analysis approach based on unsupervised clustering algorithms for identifying independent phases within a diffraction spatial map, which allowed us to identify the material distribution across a high-pressure cerium hydride. By investigating the specific compound, we also contribute to the understanding of synthesis inhomogeneities among the superhydrides, a prominent superconductor class in condensed matter physics whose characterization is highly challenging even for state-of-the-art materials techniques. The analysis framework we present may be readily extended to any correlated set of curves whose features are tied to specific entities, such as structural phases.
Materials Science (cond-mat.mtrl-sci)
14 pages, 4 figures,
Ten-valley excitonic complexes in charge-tunable monolayer WSe$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Alain Dijkstra, Amine Ben Mhenni, Dinh Van Tuan, Elif Çetiner, Muriel Schur-Wilkens, Junghwan Kim, Laurin Steiner, Kenji Watanabe, Takashi Taniguchi, Matteo Barbone, Nathan P. Wilson, Hanan Dery, Jonathan J. Finley
The optical response of two-dimensional (2D) semiconductors such as monolayer WSe$ _2$ is dominated by excitons. Enhanced interactions result in the formation of many-body excitonic complexes, which provide a testing ground for excitons and quantum many-body theories. In particular, correlated many-body excitonic complexes could constitute a limiting case that puts competing exciton descriptions to the test. Here, we report a hitherto unobserved many-body excitonic complex that emerges upon electrostatically doping both the $ K$ and $ Q$ valleys with charge carriers. We optically probe the WSe$ _2$ exciton landscape using charge-tunable devices with unusually thin gate dielectrics that facilitate doping up to several $ 10^{13}$ cm$ ^{-2}$ . In this previously unexplored regime, we observe the emergence of the thermodynamically stable state in the presence of as many as 10 filled valleys. We gain insight into the physics of this complex using magneto-optical measurements. Our results are well-described by a model where the behavior of the formed exciton complex depends on the number of distinguishable Fermi seas with which the photoexcited electron-hole pair interacts. In addition to expanding the repertoire of excitons in 2D semiconductors, the extremal nature of this complex could probe the limit of exciton models and could help answer open questions about the screened Coulomb interaction in low-dimensional semiconductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 4 figures. Extended Data: 4 figures
Collective excitations and stability of a non-Fermi liquid state near a quantum-critical point of a metal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
Yasha Gindikin, Dmitrii L. Maslov, Andrey V. Chubukov
We examine the spectral properties of collective excitations with finite angular momentum $ l$ for a system of interacting fermions near a Pomeranchuk quantum critical point, both in the Fermi liquid and non-Fermi liquid regimes. Previous studies found that deep in the Fermi liquid regime, the spectral functions for even and odd $ l$ behave differently - the latter is suppressed compared to the former because of kinematic constraints on scattering processes. The main focus of our paper is to understand how the spectral functions for even and odd $ l$ evolve as the system enters the non-Fermi liquid regime. We obtain the full scaling function for the electron polarization bubble at arbitrary $ l$ , which interpolates between the Fermi liquid and non-Fermi liquid regimes. We show that collective excitations for all $ l$ remain stable and causal throughout the crossover and right at the quantum critical point.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 5 figures
Effective synchronization amid noise-induced chaos
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
Benjamin Sorkin, Thomas A. Witten
Two remote agents with synchronized clocks may use them to act in concert and communicate. This necessitates some means of creating and maintaining synchrony. One method, not requiring any direct interaction between the agents, is exposing them to a common, environmental, stochastic forcing. This “noise-induced synchronization” only occurs under sufficiently mild forcing; stronger forcing disrupts synchronization. We investigate the regime of strong noise, where the clocks’ phases evolve chaotically. Using a simple realization of disruptive noise, we demonstrate effective synchronization. Namely, although the phases of the two clocks vary erratically, their probability distributions at a given moment become identical. We exploit this statistical synchrony to define an effective phase for an agent that closely agrees with the other’s phase. We discuss how this synchronization of ensembles broadens the range in which noise-induced synchronization can be used, and how it might be exploited in living systems.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD), Biological Physics (physics.bio-ph)
11+11 pages, 5+8 figures
Stacking-Selective Epitaxy of Rare-Earth Diantimonides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Reiley Dorrian, Jinwoong Kim, Adrian Llanos, Veronica Show, Mizuki Ohno, Nicholas Kioussis, Joseph Falson
Deterministic control of the layering configuration of two-dimensional quantum materials plays a central role in studying their emergent electronic properties. Here we demonstrate in-situ control over competing stacking configurations in thin film crystals of the rare-earth diantimonides by synthesizing in proximity to competing structural orders. A crossover between the epitaxially stabilized monoclinic structure and the orthorhombic structure commonly observed in bulk crystals is navigated through three axes; the relative cation/anion ratio, growth temperature, and choice of lanthanide ion, culminating with a comparative magnetotransport study of single-yet-distinct phase CeSb2 films. These results set the stage for an expanded search for hidden stacking configurations in layered compounds which have evaded detection.
Materials Science (cond-mat.mtrl-sci)
Tuning the magnetic properties of spin-split antiferromagnet MnTe through pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Edison P. Carlisle, George Yumnam, Stuart Calder, Bianca Haberl, Jia-Xin Xiong, Michael A. McGuire, Alex Zunger, Raphaël P. Hermann, Benjamin A. Frandsen
The hexagonal antiferromagnet MnTe has attracted enormous interest as a prototypical example of a spin-compensated magnet in which the combination of crystal and spin symmetries lifts the spin degeneracy of the electron bands without the need for spin-orbit coupling, a phenomenon called non-relativistic spin splitting (NRSS). Subgroups of NRSS are determined by the specific spin-interconverting symmetry that connects the two opposite-spin sublattices. In MnTe, this symmetry is rotation, leading to the subgroup with spin splitting away from the Brillouin zone center, often called altermagnetism. MnTe also has the largest spontaneous magnetovolume effect of any known antiferromagnet, implying strong coupling between the magnetic moment and volume. This magnetostructural coupling offers a potential knob for tuning the spin-splitting properties of MnTe. Here, we use neutron diffraction with $ \textit{in situ}$ applied pressure to determine the effects of pressure on the magnetic properties of MnTe and further explore this magnetostructural coupling. We find that applying pressure significantly increases the Néel temperature but decreases the ordered magnetic moment. We explain this as a consequence of strengthened magnetic exchange interactions under pressure, resulting in higher $ T_\mathrm{N}$ , with a simultaneous reduction of the local moment of individual Mn atoms, described here via density functional theory. This reflects the increased orbital hybridization and electron delocalization with pressure. These results show that the magnetic properties of MnTe can be controlled by pressure, opening the door to improved properties for spintronic applications through tuning via physical or chemical pressure.
Materials Science (cond-mat.mtrl-sci)
9 Pages, 6 figures, 1 table
Fractional Chern insulator states in an isolated flat band of zero Chern number
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Zuzhang Lin, Wenqi Yang, Hongyu Lu, Dawei Zhai, Wang Yao
A flat band with zero Chern number, and well isolated from the rest of Hilbert space by a gap much larger than interaction strength, is a context that has not been regarded as relevant for fractional quantum Hall physics. In this work, we present a numerical study to demonstrate the emergence of fractional Chern insulator (FCI) states in such isolated flat band with zero Chern number, which is hosted by a fluxed dice lattice with anisotropic hopping strength. While being topologically trivial, this flat band features an intriguing quantum geometry: the difference between the trace of quantum metric tensor and the Berry curvature is a constant. We consider nearest-neighbor repulsion that is weak enough to ensure that the isolated band limit is always satisfied, where band renormalization by interaction leaves the flat band quantum geometry unchanged and introduce a tiny band width only. At $ 2/3$ filling of the isolated flat band, our exact diagonalization calculations show unambiguous evidences for the FCI states, both from the many-body spectra and the many-body Chern number that demonstrates a fractionally quantized Hall conductance of $ e^2/3h$ . And the 3-fold ground state degeneracy on torus suggests that band-folding Hall crystal scenario is not compatible with the observed $ 1/3$ quantized Hall conductance at $ 2/3$ filling. We find the finite dispersion acquired from interaction renormalization, albeit tiny in the isolated band limit, is necessary for FCI to emerge. With anisotropy getting stronger towards the disconnected-chains limit, the FCI undergoes a topological phase transition to inter-chain charge density wave.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Composition-Dependent Thermoelectric Properties of Hybrid Tin Perovskites (CH3NH3)xCs1-xSnI3: Insights into Electrical and Thermal Performance
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Alexandra Ivanova, Olga Kutsemako, Aleksandra Khanina, Pavel Gorbachev, Margarita Golikova, Irina Shamova, Olga Volkova, Lev Luchnikov, Pavel Gostishchev, Danila Saranin, Vladimir Khovaylo
This work presents a comprehensive investigation of the thermoelectric properties of bulk hybrid perovskites with the general formula MAxCs1-xSnI3 (0 < x < 1). A series of bulk samples were synthesized and systematically characterized to explore the relationship between composition, microstructure, and thermoelectric performance. Compositions with intermediate MA+ content (x = 0.2 and x = 0.5) show an optimal balance between electrical conductivity and Seebeck coefficient, yielding high power factor values (0.6 - 0.7 muW/cmK2 at 423 K) and favorable thermoelectric performance with zT values up to 0.06. In contrast, compositions with MA+ contents (x = 0, x = 0.6, and x = 0.8) exhibit lower thermoelectric performance due to reduced Seebeck coefficients or suppressed conductivity. MASnI3 shows promising low-temperature thermoelectric performance with a maximum $ zT$ of 0.10 at 423 K, attributed to its rapidly increasing Seebeck coefficient. These findings highlight the importance of microstructural control and composition optimization in the development of hybrid perovskites for thermoelectric applications.
Materials Science (cond-mat.mtrl-sci)
Magnetically Modulated Electrical Switching in an Antiferromagnetic Transistor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Chung-Tao Chou, Eugene Park, Josep Ingla-Aynes, Julian Klein, Kseniia Mosina, Jagadeesh S. Moodera, Zdenek Sofer, Frances M. Ross, Luqiao Liu
A spin version of transistor, where magnetism is used to influence electrical behaviors of the semiconductor, has been a long-pursued device concept in spintronics. In this work, we experimentally study a field-effect transistor with CrSBr, a van der Waals (vdW) antiferromagnetic semiconductor, as the channel material. Unlike the weak magnetic tunability of in-plane currents previously reported in vdW magnets, the channel current of our transistor is efficiently tuned by both gate voltage and magnetic transitions, achieving a magnetoresistance ratio as high as 1500%. Combining measurement and theoretical modeling, we reveal magnetically modulated carrier concentration as the origin of the large magnetoresistance. The strategy of using both magnetic ordering and electric field in the same device to control ON/OFF states of a transistor opens a new avenue of energy-efficient spintronics for memory, logic and magnetic sensing applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Polarization switching in sliding ferroelectrics: the roles of fluctuation and domain wall
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Sliding ferroelectricity is highly attractive for its low energy barriers and fatigue resistance. As the origin of these exotic properties, its unconventional switching dynamics remains poorly understood: how an electric field drives a perpendicular sliding? Taking $ h$ -BN bilayer as a model system, its switching dynamics is studied using \textit{ab initio} calculations. The off-diagonal Born effective charge leads to the perpendicular relationship between the electric field and ionic movements. Interestingly, the rules of intrinsic coercive field are distinct between $ h$ -BN bilayer and conventional ferroelectrics. For $ h$ -BN bilayer, any perturbation breaking the in-plane symmetry plays a key role to assist the avalanche-like switching dynamics. Moreover, the exotic large off-diagonal Born effective charge near the $ P=0$ intermediate state results in a wriggling motion of domain walls in $ h$ -BN bilayer. Our results reveal the key factors in the ferroelectric switching of sliding ferroelectrics at room temperature.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures
Benchmarking Energy Calculations Using Formal Proofs
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
Ejike D. Ugwuanyi, Colin T. Jones, John Velkey, Tyler R. Josephson
Traditional approaches for validating molecular simulations rely on making software open source and transparent, incorporating unit testing, and generally employing human oversight. We propose an approach that eliminates software errors using formal logic, providing proofs of correctness. We use the Lean theorem prover and programming language to create a rigorous, mathematically verified framework for computing molecular interaction energies. We demonstrate this in LeanLJ, a package of functions, proofs, and code execution software that implements Lennard Jones energy calculations in periodic boundaries. We introduce a strategy that uses polymorphic functions and typeclasses to bridge formal proofs (about idealized Real numbers) and executable programs (over floating point numbers). Execution of LeanLJ matches the current gold standard NIST benchmarks, while providing even stronger guarantees, given LeanLJ’s grounding in formal mathematics. This approach can be extended to formally verified molecular simulations, in particular, and formally verified scientific computing software, in general. Keywords: Formal verification, Lean 4, molecular simulations, functional programming.
Statistical Mechanics (cond-mat.stat-mech)
Extended Dynamical Kubo-Toyabe Relaxation for $μ$SR study of Ion Dynamics: An Introduction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Takashi U. Ito, Ryosuke Kadono
In the analysis of the ion diffusion in metal oxides based on muon spin rotation and relaxation ($ \mu$ SR), the dynamical Kubo-Toyabe (dKT) function has been routinely used to deduce the jump frequency of ions. This is based on the two beliefs: (1) the fluctuations of the internal magnetic field $ {\bm H}(t)$ are determined solely by the relative motion of the muons to the surrounding ions, and (2) the muons are immobile due to bonding to the oxygen. However, these are not necessarily trivial, and we addressed their credibility by developing an extended dKT function corresponding to the realistic situation that only a part of the ions surrounding muon are involved in a single fluctuation of $ {\bm H}(t)$ in the ion diffusion, and investigated its behavior in detail. The results show that the new function exhibits qualitatively different behavior from the dKT function, and that it provides a way to determine whether muons or ions are in motion, as well as a means for quantitative analysis based on the assumption of immobile muons. As a typical example, we examine the earlier $ \mu^\pm$ SR results on Na$ _x$ CoO$ _2$ and demonstrate that the internal field fluctuations observed in $ \mu^+$ SR are dominated by muon self-diffusion, in contrast to previous interpretations.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 7 figures
Bridging Theory and Experiment in Materials Discovery: Machine-Learning-Assisted Prediction of Synthesizable Structures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Yu Xin, Peng Liu, Zhuohang Xie, Wenhui Mi, Pengyue Gao, Hong Jian Zhao, Jian Lv, Yanchao Wang, Yanming Ma
Even though thermodynamic energy-based crystal structure prediction (CSP) has revolutionized materials discovery, the energy-driven CSP approaches often struggle to identify experimentally realizable metastable materials synthesized through kinetically controlled pathways, creating a critical gap between theoretical predictions and experimental synthesis. Here, we propose a synthesizability-driven CSP framework that integrates symmetry-guided structure derivation with a Wyckoff encode-based machine-learning model, allowing for the efficient localization of subspaces likely to yield highly synthesizable structures. Within the identified promising subspaces, a structure-based synthesizability evaluation model, fine-tuned using recently synthesized structures to enhance predictive accuracy, is employed in conjunction with ab initio calculations to systematically identify synthesizable candidates. The framework successfully reproduces 13 experimentally known XSe (X = Sc, Ti, Mn, Fe, Ni, Cu, Zn) structures, demonstrating its effectiveness in predicting synthesizable structures. Notably, 92,310 structures are filtered from the 554,054 candidates predicted by GNoME, exhibiting great potential for promising synthesizability. Additionally, eight thermodynamically favorable Hf-X-O (X = Ti, V, and Mn) structures have been identified, among which three HfV$ _2$ O$ _7$ candidates exhibit high synthesizability, presenting viable candidates for experimental realization and potentially associated with experimentally observed temperature-induced phase transitions. This work establishes a data-driven paradigm for machine-learning-assisted inorganic materials synthesis, highlighting its potential to bridge the gap between computational predictions and experimental realization while unlocking new opportunities for the targeted discovery of novel functional materials.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Nonlinearity-induced reversal of electromagnetic non-Hermitian skin effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Junyao Wu, Rui-Chang Shen, Li Zhang, Fujia Chen, Bingbing Wang, Hongsheng Chen, Yihao Yang, Haoran Xue
The interplay between band topology and material nonlinearity gives rise to a variety of novel phenomena, such as topological solitons and nonlinearity-induced topological phase transitions. However, most previous studies fall within the Hermitian regime, leaving the impact of nonlinearity on non-Hermitian topology seldom explored. Here, we investigate the effects of nonlinearity on the non-Hermitian skin effect, a well-known non-Hermitian phenomenon induced by the point-gap topology unique to non-Hermitian systems. Interestingly, we discover a nonlinearity-induced point-gap topological phase transition accompanied by a reversal of the skin mode localization, which is distinct from previous nonlinearity-induced line-gap topological phases. This phenomenon is experimentally demonstrated in a nonlinear microwave metamaterial, where electromagnetic waves are localized around one end of the sample under a low-intensity pump, whereas at a high-intensity pump, the waves are localized around the other end. Our results open a new route towards nonlinear topological physics in non-Hermitian systems and are promising for reconfigurable topological wave manipulation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Wavefunction-Free Approach for Predicting Nonlinear Responses in Weyl Semimetals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Mohammad Yahyavi, Ilya Belopolski, Yuanjun Jin, Md Shafayat Hossain, Yilin Zhao, Jinyang Ni, Naizhou Wang, Yi-Chun Hung, Zi-Jia Cheng, Tyler A. Cochran, Tay-Rong Chang, Wei-bo Gao, Su-Yang Xu, Jia-Xin Yin, Qiong Ma, M. Zahid Hasan, Arun Bansil, Naoto Nagaosa, Guoqing Chang
By sidestepping the intractable calculations of many-body wavefunctions, density functional theory (DFT) has revolutionized the prediction of ground states of materials. However, predicting nonlinear responses–critical for next-generation quantum devices–still relies heavily on explicit wavefunctions, limiting computational efficiency. In this letter, using the circular photogalvanic effect (CPGE) in Weyl semimetals as a representative example, we realize a 1000-fold computational speedup by eliminating the explicit dependence on wavefunctions. Our approach leverages the one-to-one correspondence between free parameters of Weyl fermions and the associated responses to obtain precise wavefunction-free formulations. Applying our methodology, we systematically investigated known Weyl semimetals and revealed that Ta$ _3$ S$ _2$ exhibits photocurrents an order of magnitude greater than those observed in TaAs, with potential for an additional order-of-magnitude enhancement under strain. Our work paves the way for substantially more efficient screening and optimization of nonlinear electromagnetic properties of topological quantum materials.
Materials Science (cond-mat.mtrl-sci)
Study of magneto-thermal resistance effect in a Co50Fe50/Cu multilayer through the analysis of electron and lattice thermal conductivities
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Fuya Makino, Takamasa Hirai, Takuma Shiga, Hirofumi Suto, Hiroshi Fujihisa, Koichi Oyanagi, Satoru Kobayashi, Taisuke Sasaki, Takashi Yagi, Ken-ichi Uchida, Yuya Sakuraba
This study investigates the giant magneto-thermal resistance (GMTR) effect in a fully-bcc epitaxial Co50Fe50/Cu multilayer through both experimental and theoretical approaches. The applied magnetic field results in a giant change of the cross-plane thermal conductivity ({\Delta}\k{appa}) of 37 W m-1 K-1, which reaches 1.5 times larger than the previously reported value for a magnetic multilayer and record the highest value at room temperature among the other solid-state thermal switching materials working on different principles. We investigated the electron thermal conductivity for exploring the remarkable {\Delta}\k{appa} by the two-current-series-resistor model combined with the Wiedemann-Franz (WF) law. However, the result shows the electron contribution accounts for only 35% of the {\Delta}\k{appa}, indicating the presence of additional spin-dependent heat carriers. Further investigation of the lattice thermal conductivity, which is expected to be spin-independent, using non-equilibrium molecular dynamics (NEMD) simulations suggests a striking contrast: the additional spin-dependent heat carrier contribution is significantly enhanced in the parallel magnetization configuration but nearly negligible in the antiparallel configuration. These findings provide a fundamental insight into the origin of large GMTR effect and highlight its potential of active thermal management technologies for future electronic devices.
Materials Science (cond-mat.mtrl-sci)
18 pages , 4figures
InvDesFlow-AL: Active Learning-based Workflow for Inverse Design of Functional Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Xiao-Qi Han, Peng-Jie Guo, Ze-Feng Gao, Hao Sun, Zhong-Yi Lu
Developing inverse design methods for functional materials with specific properties is critical to advancing fields like renewable energy, catalysis, energy storage, and carbon capture. Generative models based on diffusion principles can directly produce new materials that meet performance constraints, thereby significantly accelerating the material design process. However, existing methods for generating and predicting crystal structures often remain limited by low success rates. In this work, we propose a novel inverse material design generative framework called InvDesFlow-AL, which is based on active learning strategies. This framework can iteratively optimize the material generation process to gradually guide it towards desired performance characteristics. In terms of crystal structure prediction, the InvDesFlow-AL model achieves an RMSE of 0.0423 Å, representing an 32.96% improvement in performance compared to exsisting generative models. Additionally, InvDesFlow-AL has been successfully validated in the design of low-formation-energy and low-Ehull materials. It can systematically generate materials with progressively lower formation energies while continuously expanding the exploration across diverse chemical spaces. These results fully demonstrate the effectiveness of the proposed active learning-driven generative model in accelerating material discovery and inverse design. To further prove the effectiveness of this method, we took the search for BCS superconductors under ambient pressure as an example explored by InvDesFlow-AL. As a result, we successfully identified Li(_2)AuH(_6) as a conventional BCS superconductor with an ultra-high transition temperature of 140 K. This discovery provides strong empirical support for the application of inverse design in materials science.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Artificial Intelligence (cs.AI), Machine Learning (cs.LG)
29 pages, 11 figures
Harnessing self-sensitized scintillation by supramolecular engineering of CsPbBr3 nanocrystals in dense mesoporous template nanospheres
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Xiaohe Zhou (1), Matteo L. Zaffalon (1 and 6), Emanuele Mazzola (2), Andrea Fratelli (1 and 7), Francesco Carulli (1), Chenger Wang (1), Mengda He (3), Francesco Bruni (1 and 6), Saptarshi Chakraborty (1), Leonardo Poletti (4), Francesca Rossi (4), Luca Gironi (2 and 6), Francesco Meinardi (1), Liang Li (5), Sergio Brovelli (1 and 6) ((1) Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy, (2) Dipartimento di Fisica, Università degli Studi di Milano-Bicocca, Milan, Italy, (3) School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China, (4) IMEM-CNR, Parma, Italy, (5) Macao Institute of Materials Science and Engineering (MIMSE), Macau University of Science and Technology, Taipa, Macao, China, (6) INFN - Sezione di Milano - Bicocca, Milano, Italy, (7) Nanochemistry, Istituto Italiano di Tecnologia, Genova, Italy)
Perovskite-based nanoscintillators, such as CsPbBr3 nanocrystals (NCs), are emerging as promising candidates for ionizing radiation detection, thanks to their high emission efficiency, rapid response, and facile synthesis. However, their nanoscale dimensions - smaller than the mean free path of secondary carriers - and relatively low emitter density per unit volume, limited by their high molecular weight and reabsorption losses, restrict efficient secondary carrier conversion and hamper their practical deployment. In this work, we introduce a strategy to enhance scintillation performance by organizing NCs into densely packed domains within porous SiO2 mesospheres (MSNs). This engineered architecture achieves up to a 40-fold increase in radioluminescence intensity compared to colloidal NCs, driven by improved retention and conversion of secondary charges, as corroborated by electron release measurements. This approach offers a promising pathway toward developing next-generation nanoscintillators with enhanced performance, with potential applications in high-energy physics, medical imaging, and space technologies.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Coexistence of Rashba and Dirac dispersions on the surface of centrosymmetric topological insulator decorated with transition metals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Giuseppe Cuono, Rajibul Islam, Amar Fakhredine, Carmine Autieri
The Dirac cone originates from the bulk topology, yet its primary contribution comes from the surface since spatially, the Dirac state emerges at the boundary between the trivial and topological phases. At the same time, the Rashba states emerge in regions where inversion symmetry is broken. On the surface of the centrosymmetric topological insulators, both Rashba and Dirac bands are present and their hybridization produces the giant Rashba effect, modifying both Rashba’s and Dirac’s bands. Therefore, pure Rashba and Dirac fermions are inherently incompatible on the surface of centrosymmetric topological insulators if the material is homogeneous. Inspired by recent experiments, we focused on the (111) polar surface of PbSe, which becomes a topological crystalline insulator under compressive strain, and we established the conditions under which a topological system can simultaneously host pure Rashba and Dirac surface states close to the Fermi level. The coexistence of pure Dirac and Rashba dispersions is only possible in a non-homogeneous centrosymmetric topological insulator, where the spatial origins of the two bands are effectively separated. In the experimentally observed case of PbSe, we demonstrate that a metallic overlayer induces a strong electrostatic potential gradient in the subsurface region, which in turn generates the electric field responsible for Rashba splitting in the subsurface layers. Consequently, in PbSe(111), the Rashba states arise from subsurface layers, while the Dirac states live mainly on the surface layers. Finally, we compare the properties of the Rashba in the trivial and topological phases; the calculated Rashba coefficient agrees qualitatively with the experimental results.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 10 figures
Deterministic Quantum Dot Cavity Placement Using Hyperspectral Imaging with High Spatial Accuracy and Precision
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Quirin Buchinger, Constantin Krause, Aileen Zhang, Giora Peniakov, Mohamed Helal, Yorick Reum, Andreas Theo Pfenning, Sven Höfling, Tobias Huber-Loyola
Single emitters in solid state are great sources of single and entangled photons. To boost their extraction efficiency and tailor their emission properties, they are often incorporated in photonic nanostructures. However, achieving accurate and reproducible placement inside the cavity is challenging but necessary to ensure the highest mode overlap and optimal device performance. For many cavity types – such as photonic crystal cavities or circular Bragg grating cavities – even small displacements lead to a significantly reduced emitter-cavity coupling. For circular Bragg grating cavities, this yields a significant reduction in Purcell effect, a slight reduction in efficiency and it introduces polarization on the emitted photons. Here we show a method to achieve high accuracy and precision for deterministically placed cavities on the example of circular Bragg gratings on randomly distributed semiconductor quantum dots. We introduce periodic alignment markers for improved marker detection accuracy and investigate overall imaging accuracy achieving $ (9.1 \pm 2.5) nm$ through image correction. Since circular Bragg grating cavities exhibit a strong polarization response when the emitter is displaced, they are ideal devices to probe the cavity placement accuracy far below the diffraction limit. From the measured device polarizations, we derive a total spatial process accuracy of $ (33.5 \pm 9.9) nm$ based on the raw data, and an accuracy of $ (15 \pm 11) nm$ after correcting for the system response, resulting in a device yield of $ 68 %$ for well-placed cavities.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
High Chern Number Quantum Anomalous Hall States in Haldane-Graphene Multilayers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Yuejiu Zhao, Long Zhang, Fu-Chun Zhang
Quantum anomalous Hall (QAH) systems with high Chern number ($ |C|>1$ ) are rare. This Letter introduces a Haldane-graphene multilayer heterostructure hosting QAH states with arbitrary Chern number. In a rhombohedral-stacked graphene $ N$ -layer, the Dirac points at $ K_{\pm}$ become $ N^\text{th}$ -order zeros of the low-energy effective Hamiltonian. When an extra layer of Haldane model is stacked on top of the multilayer, the high-order Dirac points are gapped out and the heterostructure enters QAH phases with $ |C|=N+1$ . Therefore, gapping out high-order Dirac points paves a new way to high Chern number QAH states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
5 pages, 3 figures
Functional approach to superfluid stiffness: Role of quantum geometry in unconventional superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Maximilian Buthenhoff, Tobias Holder, Michael M. Scherer
Non-trivial quantum geometry of electronic bands has been argued to facilitate superconductivity even for the case of flat dispersions where the conventional contribution to the superfluid weight is suppressed by the large effective mass. However, most previous work focused on the case of conventional superconductivity while many contemporary superconducting quantum materials are expected to host unconventional pairing. Here, we derive a generalized expression for the superfluid weight employing mean-field BCS theory for systems with time-reversal symmetry in the normal state and arbitrary unconventional superconducting order with zero-momentum intraband pairing. Our derivation reveals the necessity of incorporating functional derivatives of the grand potential with respect to the superconducting gap function. Through perturbative analysis in the isolated narrow-bands limit, we demonstrate that this contribution arises from quantum geometrical effects, specifically due to a non-trivial Wilczek-Zee connection. Utilizing the newly obtained expressions for the superfluid weight, we apply our framework to an extended Kane-Mele model, contrasting conventional $ s$ -wave superconductivity with chiral $ d$ -wave superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Recent progress on electron- and magnon-mediated torques
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Jia-Min Lai, Bingyue Bian, Zhonghai Yu, Kaiwei Guo, Yajing Zhang, Pengnan Zhao, Xiaoqian Zhang, Chunyang Tang, Jiasen Cao, Zhiyong Quan, Fei Wang, Xiaohong Xu
The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies. Spin-orbit torque (SOT) has emerged as a leading candidate for high-speed, high-density magnetic random-access memory due to its ultrafast switching speed and low power consumption. This review systematically explores the generation and switching mechanisms of electron-mediated torques (including both conventional SOTs and orbital torques) and magnon-mediated torques. We discuss key materials that enable these effects: heavy metals, topological insulators, low-crystal-symmetry materials, non-collinear antiferromagnets, and altermagnets for conventional SOTs; 3d, 4d, and 5d transition metals for orbital torques; and antiferromagnetic insulator NiO- and multiferroic BiFeO3-based sandwich structures for magnon torques. We emphasize that although key components of SOT devices have been demonstrated, numerous promising materials and critical questions regarding their underlying mechanisms remain to be explored. Therefore, this field represents a dynamic and rapidly evolving frontier in spintronics, offering significant potential for advancing next-generation information storage and computational technologies.
Materials Science (cond-mat.mtrl-sci)
37 pages, 14 figures
Current Conservation in the Self-Consistent Josephson Junction
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Simon Krekels, Vukan Levajac, Kristof Moors, George Simion, Bart Sorée
Conventional treatments of Josephson junctions (JJs) are generally not current-conserving. We introduce a numerical method for the self-consistent treatment of quasi-1D JJs with current conservation, with phase gradient of the order parameter in the leads matching the Josephson current through the weak link. We compare our method to standard methods and calculate the current-phase relationship (CPR) for superconductor–normal metal–superconductor JJs with different gate voltages applied to the normal metal. We show that our approach can weaken or even reverse forward skewedness of the CPR.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Preliminary version
Spin phase detection by spin current in a chiral helimagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Nan Jiang, Shota Suzuki, Issei Sasaki, Kazuki Yamada, Ryoma Kawahara, Shintaro Takada, Yusuke Shimamoto, Hiroki Shoji, Yusuke Kousaka, Jun-ichiro Ohe, Yoshihiko Togawa, Yasuhiro Niimi
Helimagnets, characterized by a helical arrangement of magnetic moments, possess unique internal degrees of freedom, including the spin phase, defined by the phase of the helical magnetic structure. Electrical detection of the spin phase is essential for both practical applications and fundamental research in helimagnets. Here, we demonstrate the electrical detection of the spin phase in a van der Waals nanoscale chiral helimagnet CrNb$ _3$ S$ _6$ using nonlocal spin valve measurements. Due to the short spin diffusion length in CrNb$ _3$ S$ _6$ ($ \sim5$ ~nm), the surface magnetic moment direction, which corresponds to the spin phase, can be detected via spin currents. The experimentally observed magnetic field dependence of the nonlocal spin valve signal is consistent with that of the surface magnetic moment in the helical magnetic structure, as supported by micromagnetic simulations. Our results establish spin currents as a powerful tool for detecting the spin phase in helimagnets, opening avenues for utilizing the spin phase as a novel internal degree of freedom in nanoscale spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 9 figures
One-dimensional extended Hubbard model coupled with an optical cavity
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
Taiga Nakamoto, Kazuaki Takasan, Naoto Tsuji
We study the one-dimensional extended Hubbard model coupled with an optical cavity, which describes an interplay of the effect of vacuum fluctuation of light and the quantum phase transition between the charge- and spin-density-wave phases. The ground state and excitation spectrum of the model are calculated by numerically exact tensor-network methods. We find that the photon number of the ground state is enhanced (suppressed) along the quantum phase transition line when the light-matter coupling is comparable to (much smaller than) the cavity frequency. We also show that the exciton peak in the optical conductivity and photon spectrum that exists without the cavity exhibits the vacuum Rabi splitting at resonance due to the light-matter interaction. This behavior is in contrast to the case without excitons, where the photon spectrum is merely broadened without splitting due to the lack of a sharp resonance.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
13 pages, 7 figures
Tunable Hilbert space fragmentation and extended critical regime
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
Mateusz Lisiecki, Janez Bonča, Marcin Mierzejewski, Jacek Herbrych, Patrycja Łydżba
Systems exhibiting the Hilbert-space fragmentation are nonergodic, and their Hamiltonians decompose into exponentially many blocks in the computational basis. In many cases, these blocks can be labeled by eigenvalues of statistically localized integrals of motion (SLIOM), which play a similar role in fragmented systems as local integrals of motion in integrable systems. While a nonzero perturbation eliminates all nontrivial conserved quantities from integrable models, we demonstrate for the $ t$ -$ J_z$ chain that an appropriately chosen perturbation may gradually eliminate SLIOMs (one by one) by progressively merging the fragmented subspaces. This gradual recovery of ergodicity manifests as an extended critical regime characterized by multiple peaks of the fidelity susceptibility. Each peak signals a change in the number of SLIOMs and blocks, as well as an ultra-slow relaxation of local observables.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
Measuring superconducting arcs by ARPES
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Andrii Kuibarov, Susmita Changdar, Alexander Fedorov, Rui Lou, Oleksandr Suvorov, Vera Misheneva, Luminita Harnagea, Iryna Kovalchuk, Sabine Wurmehl, Bernd Büchner, Sergey Borisenko
Angle-resolved photoemission spectroscopy is the leading tool for studying the symmetry and structure of the order parameter in superconductors. The recent improvement of the technique made it possible to detect the superconducting energy gap at the surface of topological t-PtBi2 via observation of the record-breaking narrow line shapes. The promising new physics uncovered requires further investigation of the spectral and gap functions of t-PtBi2, but the challenging experimental conditions severely limit the application of conventional ARPES setups. In this work, we use synchrotron-based measurements and show that the gap at the surface Fermi arc in t-PtBi2 can be detected even with more relaxed experimental conditions than in our previous laser-based studies. At the same time, using simple model of ARPES spectra, we identify the minimum requirements to detect the gap and consider cases where the gap cannot be resolved.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Field-induced electronic correlations and superconductivity in UTe$_2$ beyond 40~T
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
T. Thebault, K. Somesh, G. Lapertot, M. Nardone, A. Zitouni, M. Barragan, J. Béard, J. Billette, F. Lecouturier, S. Tardieu, D. Aoki, G. Knebel, D. Braithwaite, W. Knafo
Several superconducting phases have been discovered close to a metamagnetic transition in the heavy-fermion compound UTe$ _2$ , unveiling a close relation between its superconducting and magnetic properties. Although suspected to be of magnetic nature, the mechanisms stabilizing these superconducting phases remain mysterious. Here, we present electrical-resistivity measurements on UTe$ _2$ , with a current $ \mathbf{I}\parallel\mathbf{a}$ and under pulsed magnetic fields up to 60T rotating in the ($ \mathbf{b}$ ,$ \mathbf{c}$ ) plane. The Fermi-liquid coefficient $ A$ of the electrical resistivity reaches its maximal values at the metamagnetic transition in fields tilted by $ 30-40^\circ$ from $ \mathbf{b}$ to $ \mathbf{c}$ , and it becomes asymmetric with higher values above the metamagnetic field than below. The enhancement of $ A$ is interpreted as resulting from enhanced magnetic fluctuations, in a regime which coincides with a domain of stabilization of superconductivity beyond $ 40$ ~T. These results show that the magnetic fluctuations probed here probably play a key role in stabilizing high-field superconductivity in UTe$ _2$ and may provide further insight into the superconducting mechanisms.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
6 pages, 4 Figures + Supplemental Material with 18 pages, 16 Figures
Optoelectronic properties and performance optimization for photovoltaic applications of R3m-RbGeX$_3$ (X = Cl, Br, I) perovskites: A combined DFT and SCAPS-1D study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Piyush Kumar Dash, Palash Banarjee, Anupriya Nyayban, Subhasis Panda
In pursuit of an all-inorganic non-toxic perovskite solar cell (PSC) with enhanced performance, we have investigated the rhombohedral phase of the germanium-based rubidium halide perovskites RbGeX$ _3$ (X = Cl, Br, I). The structural analysis followed by an in-depth study of the electronic and optical properties of these materials is performed within the framework of density functional theory (DFT). A detailed investigation of the electronic properties is carried out by examining the band structure and partial density of states (PDOS). PBE and TB-mBJ exchange-correlation functionals are used with and without the spin-orbit coupling (SOC), thereby obtaining accurate predictions of the band gaps. The key optical properties such as the real and imaginary parts of the dielectric function, absorption coefficient and refractive index are studied using PBE functional and compared among the three halides. RbGeI$ _3$ exhibits the lowest band gap of 0.96 eV with the TB-mBJ + SOC functional, along with the most favorable optical properties, hence, it was identified as the most suitable candidate for the absorber layer (AL) of the PSC. SCAPS-1D simulation is performed using various input parameters for the AL such as the band gap, the effective densities of states for the conduction and valence bands and the electron and hole mobilities extracted from the DFT calculation. Performance optimization is done by exploring the impact of different inorganic hole transport layers (HTLs) and electron transport layers (ETLs). The impact of different layer thicknesses, doping densities, defect densities at the AL, ETL/AL, and AL/HTL interfaces, various back contacts, and the influence of series and shunt resistance on the overall device performance are studied. The optimized all-inorganic device demonstrated a remarkable power conversion efficiency (PCE) of $ 25.76%$ with a fill factor (FF) of $ 79.81%$ .
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, 11 figures and 6 tables. Comments are welcome
Imaging domain boundaries of rubrene thin crystallites by photoemission electron microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Moha Naeimi, Katharina Engster, Waqas Pervez, Ingo Barke, Sylvia Speller
The progress of designing organic semiconductors is extensively dependent on the quality of prepared organic molecular assemblies, since the charge transport mechanism is strongly efficient in highly ordered crystals compared to amorphous domains. Here we present a comprehensive photoemission electron microscopy (PEEM) and time-of-flight (TOF) spectroscopic study of rubrene ($ \mathrm{C}{48}\mathrm{H}{24}$ ) thin crystals focusing on recently developed orthorhombic crystalline morphologies applied in organic electronic devices. Using femtosecond pulsed lasers with photon energies between 3-6 eV, we explore the interplay between photoemission processes, crystal morphology, and defect states. In a 2-photon photoemission process (2PPE), the PEEM images reveal dominant emission localized at domain boundaries, indicating strong contributions from trap states. In contrast, in 1PPE nm excitation uniform emission across the crystal surface is observed, highlighting a fundamental difference in photoemission mechanisms. Furthermore, in the intermediate photon energy range, we identify a nonlinear, non-integer photon order, where mostly the triclinic morphology contributes to the emission, distinguishing it from the orthorhombic phase. These findings provide a new framework for assessing the quality and internal structure of organic semiconductor thin films via wavelength-dependent photoemission imaging and spectroscopy.
Materials Science (cond-mat.mtrl-sci)
A unified bonding entropy model to determine magnetic properties in graphene nanoflakes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Chang-Chun He, Jiarui Zeng, Yu-Jun Zhao, Xiao-Bao Yang
Graphene nanoflakes (GNFs) exhibit rich magnetic behaviors arising from two primary mechanisms: geometry frustration in non-Kekulé structures and electron delocalization-driven aromatic stabilization in Kekulé-type systems. Herein, we develop a unified bonding entropy model (BEM) to quantitatively characterize the magnetic properties in GNFs within a statistical framework, providing an entropy-based criterion for understanding and predicting bond occupancy numbers and unpaired electron distributions. While non-Kekulé systems naturally favor high-spin configurations due to topological frustration, the BEM reveals that even Kekulé-type GNFs can exhibit magnetic character when the entropy gain from unpaired electrons outweighs the loss of aromatic stabilization. The model predictions show excellent agreement with density functional theory calculations in terms of spin density distributions and unpaired electron counts. Our results establish bonding entropy as a general guiding principle for designing carbon-based magentic materials with tunable magnetic properties.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 6 figures
The meaning of Li diffusion in cathode materials for the cycling of Li-ion batteries: A case study on LiNi0.33Mn0.33Co0.33O2 thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
We demonstrate that for polycrystalline LiNi0.33Mn0.33Co0.33O2 c-axis textured thin film cathodes of rechargeable lithium-ion batteries, the kinetics of Li storage and release including maximum specific capacity is determined by Li diffusion. The C-rate capability and long-term cycling behavior were investigated. The films exhibited up to 30% of the expected practical capacity even at low C-rates. However, 100% capacity was achieved at very low cycling rates below 0.01C. The capacity showed a reversible behaviour with changing current density, indicating no film degradation. The C-rate capability experiment showed a square root dependence of capacities on current density, which corresponds to a diffusion-controlled process. The estimated diffusivities from the cycling experiments are independent of the current density. The Li chemical and tracer diffusivities were measured using standard electrochemical and non-electrochemical diffusion measurement techniques. Chemical diffusivities, thermodynamic factor, and hence Li tracer diffusivities were determined from potentiostatic intermittent titration (PITT) and electrochemical impedance spectroscopy (EIS) experiments as a function of electrode potential and state of charge (SOC). The diffusivities were found to be approximately independent of potential, SOC and cycle number. The Li tracer diffusivities were validated by 6Li tracer diffusion experiments with secondary ion mass spectrometry (SIMS). The diffusivities obtained by PITT and SIMS were found to be more reliable for Li uptake and release than those obtained by EIS. Based on the diffusion results, a C-rate limit for full film delithiation below 0.01 C was calculated due to slow Li diffusion.
Materials Science (cond-mat.mtrl-sci)
Spin Nernst and thermal Hall effects of topological triplons in quantum dimer magnets on the maple-leaf and star lattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
Nanse Esaki, Yutaka Akagi, Karlo Penc, Hosho Katsura
We present a comprehensive theoretical study of the topological properties of triplon excitations in spin-1/2 dimer-singlet ground states defined on the maple leaf and star lattices. Our analysis is based on a model that includes Heisenberg interactions, Dzyaloshinskii-Moriya (DM) interactions, and an external magnetic field. In the absence of an in-plane DM vector, we demonstrate that the triplon Hamiltonian maps onto the magnon Hamiltonian of the Kagome lattice, inheriting its nontrivial topological characteristics, including Berry curvature and topological invariants such as the Z2 invariant and Chern numbers. This correspondence enables us to derive analytical expressions for the spin Nernst and thermal Hall conductivities at low temperatures. Furthermore, we explore the effects of realistic finite in-plane DM interactions, uncovering multiple topological transitions and a complex thermal Hall conductivity behavior, including potential sign reversals as functions of magnetic field and temperature. Using layer groups, we also provide a symmetry classification of the star and maple leaf lattices.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 pages, 18 figures, 4 tables
Using Dopants as Agents to Probe Key Electronic Properties of Organic Semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Artem Fediai, Franz Symalla, Tobias Neumann, Wolfgang Wenzel
In organic electronics, conductivity doping is used primarily to eliminate charge injection barriers in organic light-emitting diodes, organic photovoltaics and other electronic devices. Therefore, research on conductivity doping is primarily focused on understanding and enhancing the properties of these doped layers. In contrast, this work shifts the focus from optimizing doped layers to leveraging the doping process as a tool for investigating fundamental material properties. Specifically, the dopant is used as an “agent” to enable the measurement of three critical parameters: ionization potential (IP), electron affinity (EA), and Coulomb interaction energy (VC) - that govern dopant ionization and play central roles in organic electronic devices in general. While these parameters can be measured experimentally, conventional approaches often involve intricate or indirect methods, such as spectral deconvolution, which may introduce ambiguities or fail to represent bulk properties. Here it is shown how consolidating the experimental data and simulations on the dopant ionization fraction and doped-induced conductivity can be used to estimate the mean IP or EA of the embedded organic molecule, and VC of the embedded charge-transfer complex. These results illustrate how measuring and simulating doped materials can provide access to the fundamental design parameters of organic electronic devices
Materials Science (cond-mat.mtrl-sci)
preprint
Adv. Electron. Mater. 2025, 2400988
Vortex and fractional quantum Hall phases in a rotating anisotropic Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-15 20:00 EDT
Umut Tanyeri, Ahmed Kallushi, Rıfat Onur Umucalılar, Ahmet Keleş
Realizing fractional quantum Hall (FQH) states in ultracold atomic systems remains a major goal despite numerous experimental advances in the last few decades. Recent progress in trap anisotropy control under rapid rotation has renewed interest in ultracold atomic FQH physics, enabling experiments that impart much larger angular momentum per particle and offer in-situ imaging with resolution finer than the cyclotron orbit size. In this paper, we present a theoretical investigation of a rapidly rotating anisotropic Bose gas. By projecting the full Hamiltonian, including both kinetic and interaction terms, onto the lowest Landau level, we derive a compact two-parameter model that captures the effects of interaction strength, rotation rate, and anisotropy. Using exact diagonalization and density matrix renormalization group, we obtain a phase diagram that features broken-symmetry phases and topologically ordered quantum Hall states, while also highlighting the distinctive physics arising from the system’s edges. Our results demonstrate the potential for future theoretical and experimental exploration of anisotropic quantum fluids, offering a unified framework for weakly interacting Bose condensates, vortex matter, and strongly correlated topological phases.
Quantum Gases (cond-mat.quant-gas)
9 pages, 4 figures
Nonmonotonic diffusion in sheared active suspensions of squirmers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-15 20:00 EDT
Zhouyang Ge, John F. Brady, Gwynn J. Elfring
We investigate how shear influences the dynamics of active particles in dilute to concentrated suspensions. Specifically, we focus on apolar active suspensions of squirmers, which are individually immotile but display activity-induced hydrodynamic diffusion. Under shear, the instantaneous particle velocities fluctuate more rapidly, similar to passive suspensions; however, surprisingly, the long-time diffusive dynamics can slow down and exhibit a nonmonotonic dependence on the shear rate. We show that this behavior arises from an interplay between the activity-induced persistent motion and shear-induced negative velocity autocorrelation, both of which are more pronounced at lower volume fractions. Simulations of self-propelled particles with tunable persistence support this explanation and further offer a simple mechanism to understand the observed coupling. Our results reveal a generic effect of shear on diffusion in active suspensions, elucidate how internal and external forcing interact, and provide new possibilities to modulate transport in active fluids.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Natural layered phlogopite dielectric for ultrathin two-dimensional optoelectronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Thomas Pucher, Julia Hernandez-Ruiz, Guillermo Tajuelo-Castilla, José Ángel Martín-Gago, Carmen Munuera, Andres Castellanos-Gomez
The integration of high-dielectric-constant (high-$ \kappa$ ) materials with two-dimensional (2D) semiconductors is promising to overcome performance limitations and reach their full theoretical potential. Here we show that naturally occurring phlogopite mica, exfoliated into ultrathin flakes, can serve as a robust high-$ \kappa$ dielectric layer for transition metal dichalcogenide-based 2D electronics and optoelectronics. Phlogopite’s wide bandgap (4.8 eV), high dielectric constant (11), and large breakdown field (10 MVcm$ ^{-1}$ ) enable transistors with subthreshold swings down to 100 mVdec$ ^{-1}$ , minimal hysteresis (30-60 mV) and interface trap densities comparable to state-of-the-art oxide dielectrics. Moreover, phototransistors built upon monolayer molybdenum disulfide (MoS$ _2$ ) and phlogopite exhibit responsivities up to 3.3x10$ ^{4}$ AW$ ^{-1}$ and detectivities near 10$ ^{10}$ Jones, surpassing devices based on conventional gate insulators. We further demonstrate the versatility of this natural dielectric by integrating phlogopite/MoS$ _2$ heterostructures into NMOS inverters, showcasing robust voltage gains and low-voltage operation. Our findings establish phlogopite as a promising, earth-abundant dielectric for next-generation 2D transistor technologies and high-performance photodetection.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Dynamics of charge states at the surface of a ferroelectric nanoparticle in a liquid crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Julia M. Gudenko, Oleksandr S. Pylypchuk, Victor V. Vainberg, Vladimir N. Poroshin, Denis O. Stetsenko, Igor A. Gvozdovskyy, Oleksii V. Bereznykov, Serhii E. Ivanchenko, Eugene A. Eliseev, Anna N. Morozovska
The liquid crystal with suspended ferroelectric nanoparticles is an interesting object for fundamental research of the long-range dipole-dipole interactions; as well as it is promising for optical, optoelectronic and electrochemical applications. Such suspensions can serve as basic elements for advanced nonvolatile memory cells and energy storage devices. The work studies the cells filled with a nematic liquid crystal 5CB and the cells containing 5CB with 0.5 wt.% and 1 wt.% of BaTiO3 nanoparticles with an average size of 24 nm. We analyzed the time dependences of the current flowing through the cells at constant applied voltage and the voltage dynamics in the no-load mode. The time dependences of the current and voltage show a slowing down decay rate. For the cells with BaTiO3 nanoparticles, the decrease in the decay time is characteristic. A possible physical reason for the retarding decay time rate is the indirect effect of screening charges, which cover ferroelectric nanoparticles, and slow ionic transport in the liquid crystal. To explain the dynamics of current and voltage, the finite element modeling of the polarization distribution, domain structure dynamics, and charge state of nanoparticles in a liquid crystal is performed using Landau-Ginzburg-Devonshire approach. Theoretical results confirmed the leading role of screening charges, because the surface of a ferroelectric nanoparticle adsorbs an ionic-electronic charge that partially screens its spontaneous polarization in single-domain and/or poly-domain states. When an electric field is applied to the liquid crystal with nanoparticles, it can release part of the screening charge (mainly due to the change in the polarization of the nanoparticle), which will lead to a decrease in decay time rate of the current and voltage dependences.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
18 pages, 7 figures
Origin of local magnetic exchange interaction in infiite-layer nickelates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
Yanbing Zhou, Dan Zhao, Boyun Zeng, Chengliang Xia, Yu Wang, Hanghui Chen, Tao Wu, Xianhui Chen
Significant magnetic exchange interactions have been observed in infinite-layer nickelates RNiO2 (R = La, Pr, Nd), which exhibit unconventional superconductivity upon hole doping. Despite their structural and Fermi surface similarities to cuprates, infinite-layer nickelates possess a larger charge transfer gap, which influences their magnetic exchange interactions via oxygen. In this work, we performed 17O nuclear magnetic resonance (NMR) measurements on LaNiO2 and Sr-doped LaNiO2, revealing glassy spin dynamics originating from Ni-O planes. This indicates that infinite-layer nickelates are in proximity to magnetic ordering and that magnetic correlations play a crucial role in their physics. More importantly, our analysis of the Knight shift and hyperfine coupling of 17O nuclei revealed that the Ni-Ni superexchange interaction, mediated by the {\sigma} bond between the Ni-dx2-y2 and O-p orbitals, is one order of magnitude weaker than that in cuprates. This alone cannot account for the total magnetic exchange interaction observed in nickelates. First-principles many-body calculations indicate that an interstitial s orbital near the Fermi level, coupled with the Ni-d3z2-r2 orbital, significantly enhances the superexchange interaction. This contrasts with cuprates, where magnetic interactions are predominantly governed by Cu-dx2-y2 superexchange via oxygen. Our findings provide new insights into the distinct magnetic interactions in infinite-layer nickelates and their potential role in unconventional superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
29 pages, 4 figures
Glassy dynamics and a growing structural length scale in supercooled nanoparticles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-15 20:00 EDT
Weikai Qi, Shreya Tiwary, Richard K. Bowles
We use molecular dynamics simulation to study the relationship between structure and dynamics in supercooled binary Lennard–Jones nanoparticles over a range of particle sizes. The glass transition temperature of the nanoparticles is found to be significantly lowered relative to the bulk, decreasing as $ N^{-1/3}$ with decreasing particle size. This allows the nanoparticles to sample low energy states on the potential energy landscape and we are able to study their relaxation times, measured in terms of the intermediate scattering function, and their structure, measured in terms of locally favoured structures, to low temperatures. Our work shows that the growing relaxation times in the supercooled nanoparticles are coupled with the growth of physical clusters formed from favoured local structures in a way that is well described by the Random First Order Transition entropic droplet model, but with exponents that are dependent on the nanoparticle size.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
7 pages, 7 Figures
Universal or not: Domain walls in inhomogeneous asymmetric exclusion processes with finite resources
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
We study the domain walls (DW) in an asymmetric exclusion process (TASEP) with finite resources and a bottleneck. For large values of $ \alpha,,\beta$ , which parametrize the entry and exit rates of the TASEP lane, and with {sufficiently large} resources, the DWs are independent of these parameters, revealing a {\em hitherto unknown universality}. Unusually, these are accompanied by boundary layers in the TASEP lane. These universal DWs replace the maximal current phases in TASEPs. For smaller values of $ \alpha,,\beta$ , the DWs depend upon them, and hence are nonuniversal. Our studies show that both universal and nonuniversal DWs can appear for reservoirs with finite or unlimited capacity.
Statistical Mechanics (cond-mat.stat-mech)
Preliminary version
Transients and multiperiodic responses: a hierarchy of material bits
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-15 20:00 EDT
Colin M. Meulblok, Martin van Hecke
When cyclically driven, certain disordered materials exhibit transient and multiperiodic responses that are difficult to reproduce in synthetic materials. Here, we show that elementary multiperiodic elements with period T=2, togglerons, can serve as building blocks for such responses. We experimentally realize metamaterials composed of togglerons with tunable transients and periodic responses - including odd periods. Our approach suggests a hierarchy of increasingly complex elements in frustrated media, and opens a new strategy for rational design of sequential metamaterials.
Soft Condensed Matter (cond-mat.soft)
11 pages, 8 figures
Experimental demonstration of an analogy between optical non-coherence and irreversibility of heat transport
New Submission | Other Condensed Matter (cond-mat.other) | 2025-05-15 20:00 EDT
Aleksandr Meilakhs, Claudio Pastorino, Miguel Larotonda
We probe experimentally a connection between coherence in the context of optical physics and the irreversibility present in heat transfer through an interface separating two media. The robustness of the experiment on the one hand, and the theoretical description taken from the statistical-mechanics treatment of the heat transfer problem, on the other hand, allows for the study of the arrow of time’s problem within the clean and precise framework of experimental optical physics. The central aspect of the experiment is a light beam incident and split at an interface to produce a second common interaction point again at the interface. The experiment was carried out with two light sources that only differ in their coherence length. In the case of the highly coherent light source, we were able to combine the previously split parts of the light back into a single beam. This is indicative of the reversibility of the process of coherent light transmission through the interface. The light source with low coherence length, on the contrary, does not allow for such a recombination, thus producing an irreversible process. We explain how the latter case is analogous to the process of interfacial heat transport, thus establishing an important connection between optical non-coherence and irreversibility of transport phenomena. Our finding paves the way for the study of fundamental processes in heat transfer and the surge of irreversibility in the realm of optical physics.
Other Condensed Matter (cond-mat.other), Optics (physics.optics)
24 pages, 4 figures
Mechanical work extraction from an error-prone active dynamic Szilard engine
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
Luca Cocconi, Paolo Malgaretti, Holger Stark
Isothermal information engines operate by extracting net work from a single heat bath through measurement and feedback control. In this work, we analyze a realistic active Szilard engine operating on a single active particle by means of steric interaction with an externally controlled mechanical element. In particular, we provide a comprehensive study of how finite measurement accuracy affects the engine’s work and power output, as well as the cost of operation. Having established the existence of non-trivial optima for work and power output, we study the dependence of their loci on the measurement error parameters and identify conditions for their positivity under one-shot and cyclic engine operation. By computing a suitably defined information efficiency, we also demonstrate that this engine design allows for the violation of Landauer’s bound on the efficiency of information-to-work conversion. Notably, the information efficiency for one-shot operation exhibits a discontinuous transition and a non-monotonic dependence on the measurement precision. Finally, we show that cyclic operation improves information efficiency by harvesting residual mutual information between successive measurements.
Statistical Mechanics (cond-mat.stat-mech)
13 pages, 6 figures
Super Gaussian Self-Consistent method for systems with a two-body Hamiltonian
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
A new kinetic self-consistent method is presented based on the proposed Gaussian Superposition Principle for computation of ensemble averaged observables of a macromolecule interacting via two-body forces. The latter leads to the derivation of a natural functional closure relation for the 3-point distribution functions (DF), thereby truncating a hierarchy of kinetic equations obtained from the original Langevin equation. The resulting Super Gaussian Self-Consistent (SGSC) equations for the 2-point distribution functions acquire a sufficiently tractable integro-differential form. The SGSC theory strives to yield realistic shapes of various distribution functions for any macromolecule with a generic Hamiltonian involving 2-body interaction potentials, both at equilibrium and during kinetics.
Statistical Mechanics (cond-mat.stat-mech)
8 pages LaTeX only
The Proceedings of “The XVIIth International QFTHEP Workshop,” 4-11 September 2003, Samara-Saratov, Russia, Skobeltsyn Institute of Nuclear Physics, MSU, MSU Publishing Co., (M. Dubinin, V. Savrin eds.), pp. 443-449 (2004)
Unconventional magnetic glassiness in non-centrosymmetric Sm$_7$Pd$_3$: Interplay of magnetic frustration, long-range order, and frozen domains
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Ajay Kumar, Anis Biswas, Yaroslav Mudryk
We present a comprehensive investigation of the intricate spin dynamics in the non-centrosymmetric compound Sm$ _7$ Pd$ _3$ , revealing the coexistence of spin glass, domain glass, and ferromagnetic (FM) behaviors. Magnetic field-dependent measurements indicate large coercivity, suggesting ferromagnetic domain formation below the Curie temperature ($ T_C \sim 173$ K), while temperature-dependent magnetization data point to antiferromagnetic (AFM) coupling, highlighting the competition between FM and AFM interactions. Detailed ac susceptibility, isothermal remanent magnetization, and aging effect measurements demonstrate the presence of two distinct types of glassiness in the sample, and their possible origins are discussed extensively. Magnetization measurements reveal the mixing of the J = 5/2 ground state of Sm$ ^{3+}$ with the excited J = 7/2 multiplet, lying 965 K above. The specific heat data show further crystalline electric field splitting of the J = 5/2 state into a ground-state doublet and a fourfold-degenerate excited state.
Materials Science (cond-mat.mtrl-sci)
Learned Free-Energy Functionals from Pair-Correlation Matching for Dynamical Density Functional Theory
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-15 20:00 EDT
Karnik Ram, Jacobus Dijkman, René van Roij, Jan-Willem Van de Meent, Bernd Ensing, Max Welling, Daniel Cremers
Classical density functional theory (cDFT) and dynamical density functional theory (DDFT) are modern statistical mechanical theories for modelling many-body colloidal systems at the one-body density level. The theories hinge on knowing the excess free-energy accurately, which is however not feasible for most practical applications. Dijkman et al. [Phys. Rev. Lett. 134, 056103 (2025)] recently showed how a neural excess free-energy functional for cDFT can be learned from inexpensive bulk simulations via pair-correlation matching. In this Letter, we demonstrate how this same functional can be applied to DDFT, without any retraining, to simulate non-equilibrium overdamped dynamics of inhomogeneous densities. We evaluate this on a 3D Lennard-Jones system with planar geometry under various complex external potentials and observe good agreement of the dynamical densities with those from expensive Brownian dynamic simulations, up to the limit of the adiabatic approximation. We further develop and apply an extension of DDFT to a grand-canonical system modeled after breakthrough gas adsorption studies, finding similarly good agreement. Our results demonstrate a practical route for leveraging learned free-energy functionals in DDFT, paving the way for accurate and efficient modeling of non-equilibrium systems.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
7 pages, 4 figures plus supplementary (4 pages, 2 figures, see this http URL for videos)
Bulk superinsulation and polar nematic order in nanopatterned NbTiN
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-15 20:00 EDT
A. Yu. Mironov, C. A. Trugenberger, M. C. Diamantini, D. A. Nasimov, V. M. Vinokur
We present an experimental evidence of 3D superinsulation in a nanopatterned slab of NbTiN, given by the Vogel-Fulcher-Tamman (VFT) scaling of the conductance when approaching the critical temperature from above and by the vanishing of the conductance below the transition. In the electric Meissner state, we find polar nematic order arising from ferroelectric alignement of short electric strings excited by external electromagnetic fields. Our results prove that superinsulation appears also in ordered structures provided that these are large enough, thereby confirming the origin of superinsulation as electric confinement, independent of disorder.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Nature Communications 16:4395 (2025)
Phase domain walls in coherently driven Bose-Einstein condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-15 20:00 EDT
We consider coherent states of weakly interacting bosons under the conditions of external resonant excitation, with a focus on a two-dimensional polariton fluid driven by a plane electromagnetic wave near the ground state. The coherent driving breaks the U(1) symmetry explicitly, which prevents the occurrence of quantum vortices in a uniform scalar condensate. Surprisingly, a spinor (two-component) system of the same kind admits topological excitations, such as domain walls of relative phase or confined half-vortex molecules, typical of a freely evolving spinor Bose system. Opposite-phase domains arise from the spontaneous breakdown of the spin symmetry $ (\mathbb{Z}_2)$ . Domain walls form with time even when the initial state of the system is uniform or completely disordered; they fall into different topological types distinguished by the total phase variation in the transverse direction.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
11 pages, 9 figures, 3 supplemental video files
Long-tailed dissipationless hydromechanics: weak thermalization and ergodicity breaking
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-15 20:00 EDT
Giuseppe Procopio, Chiara Pezzotti, Massimiliano Giona
We analyze the dynamic properties of dissipationless Generalized Langevin Equations in the presence of fluid inertial kernels possessing power-law tails, $ k(t) \sim t^{-\kappa}$ . While for $ \kappa >1$ the dynamics is manifestly non ergodic, no thermalization occurs, and particle motion is ballistic, new phenomena arise for $ 0 < \kappa <1$ . In this case, a form of weak thermalization appears in the presence of thermal/hydrodynamic fluctuations and attractive potentials. However, the absence of dissipation clearly emerges once an external constant force is applied: an asymptotic settling velocity cannot be achieved as the expected value of the particle velocity diverges.
Statistical Mechanics (cond-mat.stat-mech)
Analytical and Scale-Free Phase-Field Studies of $α$ to $ω$ Phase Transformation in Single Crystal Zirconium under Nonhydrostatic Loadings
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Raghunandan Pratoori, Hamed Babaei, Valery I. Levitas
Zirconium (Zr) is an important engineering material with numerous practical applications. It undergoes martensitic $ \alpha$ to $ \omega$ phase transformation (PT) at pressures that vary from 0.67 GPa to 17 GPa under different loading conditions. Despite numerous experimental and theoretical studies, the effect of the nonhydrostatic stresses is not well understood. To separate the effect of nonhydrostatic stresses from the plastic deformation, a scale-free phase field approach (PFA) for multivariant $ \alpha$ to $ \omega$ PT in a single crystal Zr under general nonhydrostatic loadings is presented. Explicit conditions for the direct and reverse PTs between austenite and martensitic variants and between martensitic variants under general stress tensor are derived and analyzed. In particular, the effect of the deviatoric stresses on the PT pressures is elucidated. It is shown that their effect cannot explain much larger reduction in the transformation pressure observed during plastic flow, i.e., specific mechanisms of strain-induced phase transformations should be involved. Under assumption of the homogeneous fields in the sample, complete analytical solutions that include stress-strain curves during the PT, PT start and finish stresses (i.e., stress hysteresis), and volume fraction of the variants, are determined for different loadings. Finite element method (FEM) solutions are found for the phase field simulations of the microstructure evolution for the same loadings, as well as for two grains of the polycrystalline sample. Macroscopic averaged characteristics of the PFA solutions are well described by an analytical solution, which also simplifies their interpretations. Obtained results are in good qualitative agreement with existing experiments. In addition, some controversies of the previous approaches are analysed.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Al$_2$MnCu: A magnetically ordered member of the Heusler alloy family despite having a valence electron count of 24
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Soumya Bhowmik, Santanu Pakhira, Renu Choudhary, Ravi Kumar, Rajashri Urkude, Biplab Ghosh, D. Bhattacharyya, Maxim Avdeev, Chandan Mazumdar
The magnetic property of the Heusler alloys can be predicted by the famous Slater-Pauling (S-P) rule, which states the total magnetic moment ($ m_t$ ) of such materials can be expressed as $ m _t,=,(N_V-24),\mu_B/f.u.$ , where $ N_V$ is the total valence electron count (VEC). Consequently, no Heusler alloys having VEC = 24 are theoretically expected as well as experimentally reported to have any magnetic ordering. Recently, a special class of Heusler alloys with 50% concentration of $ p$ -block elements (anti-Heusler) have been identified, although none of such reported compounds belong to the VEC 24 category. Here, we report a new anti-Heusler alloy, Al$ 2$ MnCu, that undergoes long-range ferromagnetic (FM) ordering with $ T{\rm C}\sim$ 315 K and a large magnetic moment of $ \sim$ 1.8 $ \mu_B$ /f.u. despite having VEC 24. A phenomenological model based on molecular orbital hybridization is also proposed to understand the magnetism and unusual deviation from the standard S-P rule.
Materials Science (cond-mat.mtrl-sci)
11 pages, 14 figures
Phys. Rev. B 111, (2025) 174417
Three regimes of a picosecond magnetoacoustics in ferromagnetic structures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
P. I. Gerevenkov, Ia. A. Mogunov, Ia. A. Filatov, N. S. Gusev, M. V. Sapozhnikov, N. E. Khokhlov, A. M. Kalashnikova
The development of magnonic devices requires energy-efficient methods for generating spin waves and controlling their parameters. Acoustic waves are known to excite spin waves resonantly with magneto-elastic wave formation or to drive non-resonantly forced magnetization oscillations. Short acoustic wavevpackets enable another resonant interaction regime - Cherenkov radiation of spin waves. This poses a question on the criteria and signatures of transitions between these three regimes of a picosecond magnetoacoustic. Here, we use the scanning magneto-optical pump-probe technique to directly reveal all three regimes of interactions of laser-driven acoustic and magnetostatic wave packets in a thin permalloy film and a waveguide on top of a (011)-Si substrate. Direct measurements of the phase velocities revealed the transition from coupled magneto-elastic wavepacket to Cherenkov-like radiation and non-resonant regime controlled by the detuning between magnon and phonon group velocities. Acoustic pulse is found to be affected by the excited magnetization dynamics only in the magneto-elastic regime.
Materials Science (cond-mat.mtrl-sci)
7 pages, 3 figures, 1 supplementary file
On-surface Synthesis of a Ferromagnetic Molecular Spin Trimer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-15 20:00 EDT
Alessio Vegliante, Manuel Vilas-Varela, Ricardo Ortiz, Francisco Romero Lara, Manish Kumar, Lucía Gómez-Rodrigo, Stefano Trivini, Fabian Schulz, Diego Soler, Hassan Ahmoum, Emilio Artacho, Thomas Frederiksen, Pavel Jelínek, Jose Ignacio Pascual, Diego Peña
Triangulenes are prototypical examples of open-shell nanographenes. Their magnetic properties, arising from the presence of unpaired $ \pi$ electrons, can be extensively tuned by modifying their size and shape or by introducing heteroatoms. Different triangulene derivatives have been designed and synthesized in recent years, thanks to the development of on-surface synthesis strategies. Triangulene-based nanostructures with polyradical character, hosting several interacting spin units, can be challenging to fabricate but are particularly interesting for potential applications in carbon-based spintronics. Here, we combine pristine and N-doped triangulenes into a more complex nanographene, \textbf{TTAT}, predicted to possess three unpaired $ \pi$ electrons delocalized along the zigzag periphery. We generate the molecule on an Au(111) surface and detect direct fingerprints of multi-radical coupling and high-spin state using scanning tunneling microscopy and spectroscopy. With the support of theoretical calculations, we show that its three radical units are localized at distinct parts of the molecule and couple via symmetric ferromagnetic interactions, which result in a $ S=3/2$ ground state, thus demonstrating the realization of a molecular ferromagnetic Heisenberg-like spin trimer
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12 pages, 5 figures, Supplementary Information included
Comparative Analysis of GFN Methods in Geometry Optimization of Small Organic Semiconductor Molecules: A DFT Benchmarking Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-15 20:00 EDT
Steve Cabrel Teguia Kouam, Jean-Pierre Tchapet Njafa, Raoult Dabou Teukam, Patrick Mvoto Kongo, Jean-Pierre Nguenang, Serge Guy Nana Engo
This study benchmarks the geometric, frequency, non-covalent (GFN) semi-empirical methods, GFN1-xTB, GFN2-xTB, GFN0-xTB, and GFN-FF, against density functional theory (DFT) for the geometry optimization of small organic semiconductor molecules. Two datasets are evaluated: a QM9-derived subset of small organic molecules and the Harvard Clean Energy Project (CEP) database of extended $ \pi$ -systems relevant to organic photovoltaics. Structural agreement is quantified using heavy-atom RMSD, equilibrium rotational constants, bond lengths, angles, and HOMO-LUMO energy gaps. Computational efficiency is assessed via CPU time and scaling behavior. GFN1-xTB and GFN2-xTB demonstrate the highest structural fidelity, while GFN-FF offers an optimal balance between accuracy and speed, particularly for larger systems. The results indicate that GFN-based methods are suitable for high-throughput molecular screening of small organic semiconductors, the choice of the method depending on the accuracy-cost trade-offs. The findings support the deployment of GFN approaches in computational pipelines for the discovery of organic electronics and materials, providing information on their strengths and limitations relative to established DFT methods.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
The PDF contains the main text and the supplementary materials, including 39 pages, 23 figures, 7 tables, and to be published in “Chemical Physics”
Exchange-driven giant magnetoelastic coupling in Sr$_4$Ru$3$O${10}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-15 20:00 EDT
Carolina A. Marques, Luke C. Rhodes, Weronika Osmolska, Harry Lane, Izidor Benedičič, Masahiro Naritsuka, Rosalba Fittipaldi, Mariateresa Lettieri, Antonio Vecchione, Peter Wahl
The interplay of electronic and structural degrees of freedom is at the heart of some of the most astonishing phenomena found in condensed matter physics, for example, the condensation of electron pairs into a macroscopically coherent ground state in superconductors. In magnetic materials, magnetic interactions couple to lattice degrees of freedom resulting in magnetoelastic coupling - an effect that is typically small and only detectable on macroscopic samples. Here, we demonstrate giant magnetoelastic coupling in the correlated itinerant ferromagnet Sr$ _4$ Ru$ _3$ O$ _{10}$ . We establish control of the magnetism in the surface layer and use this control to probe the impact of the magnetism on its electronic and structural properties. By using scanning tunneling microscopy (STM), we reveal subtle changes in the electronic structure dependent on ferromagnetic or antiferromagnetic alignment between the surface and subsurface layers. We determine the consequences of the exchange force on the relaxation of the surface layer, exhibiting a giant magnetostriction. Our results provide a direct measurement of the impact of exchange interactions and correlations on structural details in a quantum material, reveal how electronic correlations result in strong electron-lattice coupling and establish Sr$ _4$ Ru$ _3$ O$ _{10}$ as a system to study magnetism in 2D.
Strongly Correlated Electrons (cond-mat.str-el)
Main: 19 pages, 4 figures. Supplementary material: 23 pages, 11 figures