CMP Journal 2025-06-27
Statistics
Nature Nanotechnology: 1
Nature Physics: 1
Nature Reviews Materials: 1
Physical Review Letters: 8
Review of Modern Physics: 1
arXiv: 71
Nature Nanotechnology
Nanopore detection of single-nucleotide RNA mutations and modifications with programmable nanolatches
Original Paper | Biosensors | 2025-06-26 20:00 EDT
Yunxuan Li, Siong Chen Meng, Yesheng Wang, Casey M. Platnich, Max K. Earle, Elli Mylona, Plamena Naydenova, Stephen Baker, Jinbo Zhu, Ulrich F. Keyser
RNA mutations and modifications have been implicated in a wide range of pathophysiologies. However, current RNA detection methods are hindered by data complexity and error-prone protocols, restricting their widespread use. Here we present a solid-state nanopore-based approach, RNA single-nucleotide characterization and analysis nanolatch (RNA-SCAN) system, which simplifies the detection of nucleotide mutations and modifications in RNA with high resolution. Using phage RNA as a template, we tested multiple sequences and chemical modifications on nanolatches, allowing the detection of mismatches caused by nucleotide mutations through significant changes in positive event ratios using single-molecule nanopore measurements. This approach is also sensitive to modifications that either strengthen or weaken the interaction between the target RNA sequence and the nanolatch. As a proof-of-concept, we demonstrate successful discrimination of Escherichia coli and Salmonella spp. from total RNA based on nucleotide variations in their 16S rRNA, as well as quantification of different Salmonella spp. and detection of m5C1407 modification on E. coli 16S rRNA. The RNA-SCAN approach demonstrates the feasibility of combining RNA/DNA hybrid nanotechnology with nanopore sensing and diagnosing RNA-related health conditions.
Biosensors, Nanopores, RNA nanotechnology
Nature Physics
Dynamic phase transition in 1T-TaS2 via a thermal quench
Original Paper | Electronic devices | 2025-06-26 20:00 EDT
Alberto de la Torre, Qiaochu Wang, Yasamin Masoumi, Benjamin Campbell, Jake V. Riffle, Dushyanthini Balasundaram, Patrick M. Vora, Jacob P. C. Ruff, Gregory A. Fiete, Shawna M. Hollen, Kemp W. Plumb
Ultrafast light-matter interaction has emerged as a mechanism to control the macroscopic properties of quantum materials. However, technological applications of photoinduced phases are limited by their ultrashort lifetimes and the low temperatures required for their stabilization. One such phase is the hidden metallic charge density wave state in 1T-TaS2, whose origin and stability above cryogenic temperatures remain the subject of debate. Here, we demonstrate that this phase can be stabilized at thermal equilibrium by accessing a mixed charge density wave order regime through thermal quenching. Using X-ray high-dynamic-range reciprocal space mapping and scanning tunnelling spectroscopy, we reveal the coexistence of commensurate charge density wave and hidden metallic charge density wave domains up to 210 K. Our findings show that each order parameter breaks basal plane mirror symmetry with different chiral orientations and induces out-of-plane unit cell tripling in the hidden phase. Despite metallic domain walls and a finite density of states, the bulk resistance remains insulating due to charge density wave stacking disorder. Our results establish the hidden state as a thermally stable phase and introduce an alternative mechanism for switchable metallic behaviour in thin flakes of 1T-TaS2 and similar materials with competing phases.
Electronic devices, Electronic properties and materials, Phase transitions and critical phenomena
Nature Reviews Materials
Synergistic integration of materials in medical microrobots for advanced imaging and actuation
Review Paper | Biomedical engineering | 2025-06-26 20:00 EDT
Paul Wrede, Eva Remlova, Yi Chen, Xosé Luís Deán-Ben, Metin Sitti, Daniel Razansky
Medical microrobotics capitalizes on smart materials to target specific body sites effectively, precisely and locally, thus holding promise to revolutionize precision medicine in the future. Advances in material science and microfabrication or nanofabrication techniques have facilitated the implementation of a myriad of functionalities into microrobots. Efficient navigation and monitoring of microrobots within the highly dynamic and often inaccessible environment of living mammalian tissues is paramount for their effective in vivo applications and eventual clinical translation. This need calls for the deployment of biomedical imaging modalities with adequate sensitivity, penetration depth and spatiotemporal resolution, as well as for efficient integration of biocompatible contrast materials into microrobots. In this Review, we discuss emerging approaches for multiplexed imaging and actuation of microrobots within complex biological environments, focusing on the synergistic combination of responsive and contrasting materials to achieve desired morphological and functional properties, in vivo visibility and biosafety. The convergence between microrobotics and biomedical imaging paves the way for a new generation of medical microrobots enabling the use of energy for both mechanical actuation and efficient monitoring of their activity in vivo.
Biomedical engineering, Materials for devices
Physical Review Letters
Stability and Loop Models from Decohering Non-Abelian Topological Order
Research article | Open quantum systems & decoherence | 2025-06-26 06:00 EDT
Pablo Sala and Ruben Verresen
Decohering topological order (TO) is central to the many-body physics of open quantum matter and decoding transitions. We identify statistical mechanical models for decohering non-Abelian TOs, which have been crucial for understanding the error threshold of Abelian stabilizer codes. The decohered density matrix can be described by loop models, whose topological loop weight $N$ is the quantum dimension of the decohering anyon—reducing to the Ising model if $N=1$. In particular, the R'enyi-$n$ moments correspond to $n$ coupled $\mathrm{O}(N)$ loop models. Moreover, by diagonalizing the density matrix at maximal error rate, we connect the fidelity between two logically distinct ground states to random $\mathrm{O}(N)$ loop and spin models. We find a remarkable stability to quantum channels which proliferate non-Abelian anyons with large quantum dimension, with the possibility of critical phases for smaller dimensions. Intuitively, this stability is due to non-Abelian anyons not admitting finite-depth string operators. We confirm our framework with exact results for Kitaev quantum double models, and with numerical simulations for the non-Abelian phase of the Kitaev honeycomb model. Our work opens up the possibility of non-Abelian TO being robust against maximally proliferating certain anyons, which can inform error-correction studies of these topological memories.
Phys. Rev. Lett. 134, 250403 (2025)
Open quantum systems & decoherence, Quantum memories, Topological order
Gluing via Intersection Theory
Research article | Differential equations | 2025-06-26 06:00 EDT
Giulio Crisanti, Burkhard Eden, Maximilian Gottwald, Pierpaolo Mastrolia, and Tobias Scherdin
Higher-point functions in $\mathcal{N}=4$ super Yang-Mills theory can be constructed using integrability by triangulating the surfaces on which Feynman graphs would be drawn. It remains hard to analytically compute the necessary regluing of the tiles by virtual particles. We propose a new approach to study a series of residues encountered in the two-particle gluing of the planar one-loop five-point function of stress tensor multiplets. After exposing the twisted period nature of the integral functions, we employ intersection theory to derive canonical differential equations and present a solution.
Phys. Rev. Lett. 134, 251603 (2025)
Differential equations, Mathematical physics methods
Explaining Snowball-in-Hell Phenomena in Heavy-Ion Collisions Using a Novel Thermodynamic Variable
Relativistic heavy-ion collisions | 2025-06-26 06:00 EDT
Eric Braaten, Kevin Ingles, and Justin Pickett
A loosely bound hadronic molecule produced by a relativistic heavy-ion collision has been described as a ‘’snowball in hell’’ since it emerges from a hadron resonance gas whose temperature is orders of magnitude larger than the binding energy of the molecule. This remarkable phenomenon can be explained in terms of a novel thermodynamic variable called the ‘’contact’’ that is conjugate to the binding momentum of the molecule. The production rate of the molecule can be expressed in terms of the contact density at the kinetic freeze-out of the hadron resonance gas. It approaches a nonzero limit as the binding energy goes to 0.
Phys. Rev. Lett. 134, 252301 (2025)
Relativistic heavy-ion collisions
Reduction in Nuclear Size and Quadrupole Deformation of High-Spin Isomers of $^{127,129}\mathrm{In}$
Research article | High spin states | 2025-06-26 06:00 EDT
A. R. Vernon et al.
We employed laser spectroscopy of atomic transitions to measure the nuclear charge radii and electromagnetic properties of the high-spin isomeric states in neutron-rich indium isotopes ($Z=49$) near the closed proton and neutron shells at $Z=50$ and $N=82$. Our data reveal a reduction in the nuclear charge radius and intrinsic quadrupole moment when protons and neutrons are fully aligned in $^{129}\mathrm{In}(N=80)$, to form the high spin isomer. Such a reduction is not observed in $^{127}\mathrm{In}(N=78)$, where more complex configurations can be formed by the existence of four neutron holes. These observations are not consistently described by nuclear theory.
Phys. Rev. Lett. 134, 252501 (2025)
High spin states, Nuclear charge distribution, Nuclear forces, Nuclear many-body theory, Nuclear radii, Nuclear shapes and moments, Nuclear spin & parity, Nuclear structure & decays, Spectroscopic factors & electromagnetic moments
Towards the Generation of Petawatt Near-Infrared Few-Cycle Light Pulses via Forward Raman Amplification in Plasma
Research article | Laser-plasma interactions | 2025-06-26 06:00 EDT
Zhi-Yu Lei, Zheng-Ming Sheng, Su-Ming Weng, Min Chen, and Jie Zhang
Light amplification toward extremely high power in the infrared regime remains a significant challenge due to the lack of suitable gain media. Here we propose a new scheme to amplify a laser pulse with tunable wavelengths toward extremely high power via forward Raman amplification in plasma. Different from previously proposed schemes based upon backward Raman or Brillouin amplification, our scheme involves a pump pulse and a seed pulse copropagating in moderate density plasma, with the phase matching conditions for forward Raman scattering fulfilled. Due to their group velocity difference in plasma, the pump with a shorter wavelength and longer duration will chase the seed and transfer energy to the latter efficiently. Analytical models for both linear and nonlinear stages of amplification as well as particle-in-cell simulation show that, by employing a $1.0\text{ }\text{ }\mathrm{\mu }\mathrm{m}$ pump laser, a $1.8\text{ }\text{ }\mathrm{\mu }\mathrm{m}$ seed pulse can be amplified ${10}^{4}$ times in its intensity and then self-compressed to nearly single-cycle. Our scheme shows the merits of high efficiency, high compactness, and relatively easy implementation with the copropagating configuration, which may provide a unique route toward the petawatt few-cycle infrared laser pulses.
Phys. Rev. Lett. 134, 255001 (2025)
Laser-plasma interactions, Plasma optics, Stimulated Brillouin & Raman scattering in plasmas
Highly Tunable Valley Polarization of Potential-Trapped Moir'e Excitons in ${\mathrm{WSe}}{2}/{\mathrm{WS}}{2}$ Heterojunctions
Research article | Luminescence | 2025-06-26 06:00 EDT
Yueh-Chun Wu, Matthew DeCapua, ZhongChen Xu, Takashi Taniguchi, Kenji Watanabe, YouGuo Shi, and Jun Yan
Moir'e superlattices created by stacking atomic layers of transition metal dichalcogenide semiconductors have emerged as a class of fascinating artificial photonic and electronic materials. An appealing attribute of these structures is the inheritance of the valley degree of freedom from the constituent monolayers. Recent studies show evidence that the valley polarization of the moir'e excitons is highly tunable. In heterojunctions of ${\mathrm{WSe}}{2}/{\mathrm{WS}}{2}$, marked improvement in valley polarization is observed by increasing optical excitation power, a behavior that is quite distinct from the monolayers, and lacks a clear understanding so far. In this Letter, we show that this highly tunable valley property arises from filling of the moir'e superlattice, which provides an intriguing mechanism for engineering these quantum opto-valleytronic platforms. Our data further demonstrate that the long-range electron-hole exchange interaction, despite being significantly weakened in the junctions, is the dominant source of moir'e exciton intervalley scattering at low population. Using magnetic field tuning, we quantitatively determine the exchange interaction strength to be 0.03 and 0.24 meV for 0^\circ{} and 60^\circ{} twisted samples, respectively, in our experiments, about 1 order of magnitude weaker than that in the monolayers.
Phys. Rev. Lett. 134, 256402 (2025)
Luminescence, Spin-orbit coupling, Valley degrees of freedom, Transition metal dichalcogenides, Twisted heterostructures
Chiral Gapless Spin Liquid in Hyperbolic Space
Research article | Quantum spin liquid | 2025-06-26 06:00 EDT
Felix Dusel, Tobias Hofmann, Atanu Maity, Rémy Mosseri, Julien Vidal, Yasir Iqbal, Martin Greiter, and Ronny Thomale
We analyze the Kitaev model on the ${9,3}$ hyperbolic lattice. The ${9,3}$ is formed by a regular tricoordinated tiling of nonagons, where the three-color coding of bonds according to the inequivalent Kitaev Ising spin couplings yields the natural generalization of the original Kitaev model for Euclidean regular honeycomb tiling. Upon investigation of the bulk spectrum for large finite size droplets, we identify a gapless chiral ${\mathbb{Z}}_{2}$ spin liquid state featuring spontaneous time-reversal symmetry breaking. Because of its noncommutative translation group structure, such type of hyperbolic spin liquid is conjectured to feature chiral quasiparticles with a potentially non-Abelian Bloch profile.
Phys. Rev. Lett. 134, 256604 (2025)
Quantum spin liquid, Kitaev model
Deterministic Generation of a Single-Byte Electric Skyrmion Bubble
Research article | Ferroelectricity | 2025-06-26 06:00 EDT
Peng Chen, Yousra Nahas, Sergei Prokhorenko, and Laurent Bellaiche
Polar skyrmion bubbles are spherical electric solitons offering multiple new functionalities for the next generation of electronic devices. In this study, we explore the formation of these particlelike entities at room temperature within a ferroelectric nanostructure composed of a nanodot embedded in a thin film. Our findings emphasize the unique capability of this specific geometry to host various types of electric solitons, particularly to allow for a low-power encoding of a single-byte skyrmion bubble at the precise location of the nanodot through a sequence of bias voltage signals. This intricate process is found to be driven by the emergence of a negative nonlocal dielectric response in nanoscale ultrathin film. Our findings offer practical insights into the controlled encoding operations of polar defects at targeted locations, thereby paving the way for the practical implementation of emerging topological ferroelectrics in memory and logic devices.
Phys. Rev. Lett. 134, 256802 (2025)
Ferroelectricity, Polarization vortices, Skyrmions, Ferroelectrics, Nanostructures, First-principles calculations
Review of Modern Physics
Order and disorder at the atomic scale: Microscopy applied to semiconductors
Research article | Disordered alloys | 2025-06-26 06:00 EDT
Enrico Di Russo, Tom Verstijnen, Paul Koenraad, Konstantinos Pantzas, Gilles Patriarche, and Lorenzo Rigutti
Atomic-scale details, especially those of disorder, are important for material properties, especially in semiconductors, but they are also extremely difficult to measure. Real-space methods can give direct access to this information, but typically, that access is limited. This review reports the application of three real-space techniques for measuring disorder to compound semiconductor materials: scanning tunneling microscopy, transmission electron microscopy, and atom-probe microscopy. Where possible, it emphasizes cases in which the probes have been combined to achieve a more complete picture of the defects.
Rev. Mod. Phys. 97, 025006 (2025)
Disordered alloys, Ordered compounds, Semiconductor compounds, Electron microscopy, Field emission & field-ion microscopy, Scanning tunneling microscopy
arXiv
Near-surface Defects Break Symmetry in Water Adsorption on CeO$_{2-x}$(111)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Oscar Custance, Manuel González Lastre, Kyungmin Kim, Estefanía Fernandez-Villanueva, Pablo Pou, Masayuki Abe, Hossein Sepehri-Amin, Shigeki Kawai, M. Verónica Ganduglia-Pirovano, Rubén Pérez
Water interactions with oxygen-deficient cerium dioxide (CeO$ _2$ ) surfaces are central to hydrogen production and catalytic redox reactions, but the atomic-scale details of how defects influence adsorption and reactivity remain elusive. Here, we unveil how water adsorbs on partially reduced CeO$ _{2-x}$ (111) using atomic force microscopy (AFM) with chemically sensitive, oxygen-terminated probes, combined with first-principles calculations. Our AFM imaging reveals water molecules as sharp, asymmetric boomerang-like features radically departing from the symmetric triangular motifs previously attributed to molecular water. Strikingly, these features localize near subsurface defects. While the experiments are carried out at cryogenic temperature, water was dosed at room temperature, capturing configurations relevant to initial adsorption events in catalytic processes. Density functional theory identifies Ce$ ^{3+}$ sites adjacent to subsurface vacancies as the thermodynamically favored adsorption sites, where defect-induced symmetry breaking governs water orientation. Force spectroscopy and simulations further distinguish Ce$ ^{3+}$ from Ce$ ^{4+}$ centers through their unique interaction signatures. By resolving how subsurface defects control water adsorption at the atomic scale, this work demonstrates the power of chemically selective AFM for probing site-specific reactivity in oxide catalysts, laying the groundwork for direct investigations of complex systems such as single-atom catalysts, metal-support interfaces, and defect-engineered oxides.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other), Atomic and Molecular Clusters (physics.atm-clus), Chemical Physics (physics.chem-ph)
Beyond one-loop: higher-order effects on Gross-Neveu-Yukawa tensorial criticality
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
We study the Gross-Neveu-Yukawa field theory for the SO($ N$ ) symmetric traceless rank-two tensor order parameter coupled to Majorana fermions using the $ \epsilon$ -expansion around upper critical dimensions of $ 3+1$ to two loops. Previously we established in the one-loop calculation that the theory does not exhibit a critical fixed point for $ N \geq 4$ , but that nevertheless the stable fixed point inevitably emerges at a large number of fermion flavors $ N_f$ . For $ N_f < N_{f,c1} \approx N/2$ , no critical fixed point exists; for $ N_{f,c1} < N_f < N_{f,c2}$ , a real critical fixed point emerges from the complex plane but fails to satisfy the additional stability conditions necessary for a continuous phase transition; and finally only for $ N_f > N_{f,c2} \approx N$ , the fixed point satisfies the stability conditions as well. In the present work we compute the $ O(\epsilon)$ (two-loop) corrections to the critical flavour numbers $ N_{f,c1} $ and $ N_{f,c2}$ . Most importantly, we observe a sharp decrease in $ N_{f,c2}$ from its one-loop value, which brings it closer to the point $ N_f =1$ relevant to the standard Gross-Neveu model. Some three-loop results are also presented and discussed.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
11 page, 4 figures
Quantized Chern-Simons Axion Coupling in Anomalous Floquet Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Lucila Peralta Gavensky, Nathan Goldman, Gonzalo Usaj
Quantized bulk response functions are hallmark signatures of topological phases, but their manifestation in periodically driven (Floquet) systems is not yet fully established. Here, we show that two-dimensional anomalous Floquet systems exhibit a quantized bulk response encoded in a Chern-Simons axion (CSA) coupling angle, reflecting a topological magnetoelectric effect analogous to that in three-dimensional insulators. The periodic drive introduces an emergent “photon” dimension, allowing the system to be viewed as a three-dimensional Sambe lattice. Within this framework, cross-correlated responses such as photon-space polarization and magnetization density, emerge as physical signatures of the CSA coupling. The CSA angle, constructed from the non-Abelian Berry connection of Floquet states, admits a natural interpretation in terms of the geometry of hybrid Wannier states. These results provide a unified framework linking Floquet band topology to quantized bulk observables.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
6 pages, 3 figures
Tuning between a fractional topological insulator and competing phases at $ν_\mathrm{T}=2/3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
Roger Brunner, Titus Neupert, Glenn Wagner
We study a spinful, time-reversal symmetric lowest Landau level model for a flatband quantum spin Hall system at total filling fraction $ \nu_\mathrm{T}=2/3$ . Such models are relevant, e.g. for spin-valley locked moiré transition metal dichalcogenides. The opposite Chern number of the two spins hinders the formation of a quantum Hall ferromagnet, instead favouring other phases. We study the phase diagram in dependence on different short-range Haldane pseudopotentials $ V_m$ and uncover several phases: A fractional topological insulator, a phase separated state, a spin-polarized fractional quantum Hall state, and the partially particle-hole transformed Halperin (111) state. The effect of the pseudopotentials $ V_m$ depends on the parity of $ m$ , the relative angular momentum.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8+16 pages, 5+21 figures
Ultrahigh Anomalous Nernst Thermopower and Thermal Hall Angle in YbMnBi2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Jiamin Wen, Kaustuv Manna, Dung Vu, Subhadeep Bej, Yu Pan, Claudia Felser, Brian Skinner, Joseph P. Heremans
Thermoelectrics (TEs) are solid-state devices that can realize heat-electricity conversion. Transverse TEs require materials with a large Nernst effect, which typically requires a strong applied magnetic field. However, topological materials with magnetic order offer an alternative pathway for achieving large Nernst via the anomalous Hall effect and the accompanying anomalous Nernst effect (ANE) that arise from band topology. Here, we show that YbMnBi2 with a low Hall density and a chemical potential near the Weyl points has, to the best of our knowledge, the highest ANE-dominated Nernst thermopower of any magnetic material, with $ S_{yx}$ around 110 $ \mu$ V/K ($ T$ = 254 K, 5 T < $ |\mu_0 H|$ < 9 T applied along the spin canting direction), due to the synergism between classical contributions from filled electron bands, large Hall conductivity of topological origin, and large resistivity anisotropy. An appreciable thermal Hall angle of $ 0.02 < (\nabla_y T)/(\nabla_x T) < 0.06$ was observed (40 K < $ T$ < 310 K, $ \mu_0 H$ = 9 T).
Materials Science (cond-mat.mtrl-sci)
24+30 pages, 4+12 figures, 1+2 tables
Pairing symmetry and superconductivity in La$_3$Ni$_2$O$_7$ thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Wenyuan Qiu, Zhihui Luo, Xunwu Hu, Dao-Xin Yao
The recent discovery of superconductivity with a transition temperature $ T_c$ over 40 K in La$ _3$ Ni$ _2$ O$ 7$ and (La,Pr)$ {3}$ Ni$ 2$ O$ 7$ thin films at ambient pressure marks an important step in the field of nickelate superconductors. Here, we perform a renormalized mean-field theory study of the superconductivity in $ \mathrm{La_3Ni_2O_7}$ thin films, using a bilayer two-orbital $ t-J$ model. Our result reveals an $ s\pm$ -wave pairing symmetry driven by the strong interlayer superexchange coupling of $ d{z^2}$ orbital, resembling the pressurized bulk case. Also, we roughly reproduce the experimentally reported nodeless shape of the superconducting gap at the $ \beta$ pocket and the superconducting $ T_c$ . To gain insight into the orbital feature of superconductivity, we explore the projection of different pairing bonds on Fermi surface. We find that the nodeless gap at $ \beta$ pocket is related to the interlayer pairing within both $ d{z^2}$ and $ d{x^2-y^2}$ orbitals, in which the latter is triggered by the former through hybridization, and both hold the same sign.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
5 pages,4 figures
Bosonized theory of de Haas-van Alphen quantum oscillation in Fermi liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
The de Haas-van Alphen effect (dHvA) of a 2d Fermi liquid remains poorly understood, due to the $ \sim\mathcal{O}(1)$ contribution to the oscillations of grand potential from the oscillatory part of the fermionic self energy, which has no known closed-form solution. In this work, we solve this problem via coadjoint-orbit bosonization of the Fermi surface. Compared with the fermionic formalism, the issue of the oscillatory self energy is circumvented. As an effective field theory, Landau parameters $ F_{n}$ directly enter the theory. We use the bosonized theory to derive the energies of cyclotron resonance and specific heat, which are consistent with Fermi liquid theory. Via a mode expansion, we show that the problem of dHvA is reduced to 0+1D quantum mechanics. We obtain analytic expressions for the behavior of dHvA at low and high temperatures, which deviate from the well-known Lifshitz-Kosevich formula. We contrast this behavior with that of 3d Fermi liquids, for which we show such deviations are parametrically small. We discuss the effects of disorder on dHvA within the bosonized theory.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
31 pages, 2 figures. Comments welcome
The Interacting Energy Bands of Magic Angle Twisted Bilayer Graphene Revealed by the Quantum Twisting Microscope
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
J. Xiao, A. Inbar, J. Birkbeck, N. Gershon, Y. Zamir, T. Taniguchi, K. Watanabe, E. Berg, S. Ilani
Electron interactions in quantum materials fundamentally shape their energy bands and, with them, the material’s most intriguing quantum phases. Magic angle twisted bilayer graphene (MATBG) has emerged as a model system, where flat bands give rise to a variety of such phases, yet the precise nature of these bands has remained elusive due to the lack of high-resolution momentum space probes. Here, we use the quantum twisting microscope (QTM) to directly image the interacting energy bands of MATBG with unprecedented momentum and energy resolution. Away from the magic angle, the observed bands closely follow the single-particle theory. At the magic angle, however, we observe bands that are completely transformed by interactions, exhibiting light and heavy electronic character at different parts of momentum space. Upon doping, the interplay between these light and heavy components gives rise to a variety of striking phenomena, including interaction-induced bandwidth renormalization, Mott-like cascades of the heavy particles, and Dirac revivals of the light particles. We also uncover a persistent low-energy excitation tied to the heavy sector, suggesting a new unaccounted degree of freedom. These results resolve the long-standing puzzle in MATBG - the dual nature of its electrons - by showing that it originates from electrons at different momenta within the same topological heavy fermion-like flat bands. More broadly, our results establish the QTM as a powerful tool for high-resolution spectroscopic studies of quantum materials previously inaccessible to conventional techniques.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Symmetry Classification of Magnetic Orders and Emergence of Spin-Orbit Magnetism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Yuntian Liu, Xiaobing Chen, Yutong Yu, Qihang Liu
Magnetism, a fundamental concept predating condensed matter physics, has achieved significant advancements in recent decades, driven by its potential for next-generation storage devices. Meanwhile, the classification of magnetic orders, even for the most fundamental concepts like ferromagnetism (FM) and antiferromagnetism (AFM), has encountered unprecedented challenges since the discovery of unconventional magnets and advancements in antiferromagnetic spintronics. Here, we present a rigorous classification of magnetic order using state-of-the-art spin space group (SSG) theory. Based on whether the net magnetic moment is constrained to zero by SSG, magnetic order is unambiguously dichotomized into FM (including ferrimagnetism) and AFM. Additionally, we classify AFM geometries into four categories – primary, bi-color, spiral, and multi-axial – based on periodic spin propagation beyond the symmetry operations of magnetic space groups. We then introduce a distinct magnetic phase, dubbed spin-orbit magnetism, characterized by its unique behavior involving the spin-orbit coupling (SOC) order parameter and SOC-driven phase transition. We further create an oriented SSG description, i.e., SSG with a fixed magnetic configuration, apply the framework to 2,065 experimentally validated magnetic materials in MAGNDATA database, and identify over 220 spin-orbit magnets with distinct spin and orbital magnetization mechanisms. Implemented by the online program FINDSPINGROUP, our work establishes a universal symmetry standard for magnetic order classification, offering new understandings of unconventional magnets and broad applicability in spintronics and quantum material design.
Materials Science (cond-mat.mtrl-sci)
Under review, submitted on 28 Feb, 2025
Pull-off strength of mushroom-shaped fibrils adhered to rigid substrates
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
C. Betegón, C. Rodríguez, E. Martínez-Pañeda, R.M. McMeeking
The exceptional adhesion properties of biological fibrillar structures – such as those found in geckos – have inspired the development of synthetic adhesive surfaces. Among these, mushroom-shaped fibrils have demonstrated superior pull-off strength compared to other geometries. In this study, we employ a computational approach based on a Dugdale cohesive zone model to analyze the detachment behavior of these fibrils when adhered to a rigid substrate. The results provide complete pull-off curves, revealing that the separation process is inherently unstable under load control, regardless of whether detachment initiates at the fibril edge or center. Our findings show that fibrils with a wide, thin mushroom cap effectively reduce stress concentrations and promote central detachment, leading to enhanced adhesion. However, detachment from the center is not observed in all geometries, whereas edge detachment can occur under certain conditions in all cases. Additionally, we investigate the impact of adhesion defects at the fibril center, showing that they can significantly reduce pull-off strength, particularly at high values of the dimensionless parameter \c{hi}. These insights contribute to the optimization of bio-inspired adhesives and microstructured surfaces for various engineering applications.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Computational Engineering, Finance, and Science (cs.CE), Applied Physics (physics.app-ph), Biological Physics (physics.bio-ph)
From the dynamic to the static glass transition via hypersonic measurements using Brillouin spectroscopy
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Jan-Kristian Krüger, Rafael J. Jiménez Riobóo, Bernd Wetzel, Andreas Klingler
For the fragile, low-molecular-weight liquid diglycidyl ether of bisphenol A (DGEBA), we report on the dynamic glass transition and a further acoustic anomaly in the vicinity of the thermal glass transition based on hypersonic investigations of the longitudinal elastic modulus using Brillouin spectroscopy. This additional acoustic anomaly of the longitudinally polarized phonon is confirmed by the occurrence of an anomaly of the shear phonon at the same thermal glass transition temperature. Analysis of the generalized Cauchy relation suggests that both anomalies are coupled to a glass transition phenomenon independent of the so-called {\alpha}-relaxation process.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
5 pages, 5 figures
BaCd2P2: a defect-resistant “GaAs”
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Gideon Kassa, Zhenkun Yuan, Muhammad R. Hasan, Guillermo L. Esparza, David P. Fenning, Geoffroy Hautier, Kirill Kovnir, Jifeng Liu
BaCd2P2 (BCP) has recently been identified as a promising solar absorber with excellent optoelectronic properties. Here we demonstrate the defect tolerance in BCP by comparing its optoelectronic quality with that of the well studied absorber GaAs. Despite having a low precursor purity, our synthesized BCP samples exhibit a bright band-to-band room-temperature photoluminescence intensity, an implied open-circuit voltage of 1.0 V at AM1.5, and a carrier lifetime of about 300 ns, all higher than those of GaAs samples obtained from a high-purity single-crystalline wafer. In contrast, GaAs samples synthesized using similar methods as BCP show no band-to-band photoluminescence emissions. To understand the higher optoelectronic quality of BCP, we perform first-principles defect calculations and show that BCP has a much lower Shockley-Read-Hall nonradiative recombination rate compared to GaAs. Our results reveal robust impurity and defect tolerance in BCP, demonstrating its high photovoltaic potential.
Materials Science (cond-mat.mtrl-sci)
For DFT calculation and PL fitting code, see this https URL
Nonequilibrium quench dynamics of Bose-Einstein condensates of microwave-shielded polar molecules
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-27 20:00 EDT
We theoretically investigate the non-equilibrium dynamics of homogeneous ultracold Bose gases of microwave-shielded polar molecules following a sudden quench of the scattering length at zero temperature. We calculate in particular the quantum depletion, the anomalous density, the condensate fluctuations, and the pair correlation function using both the time-dependent Bogoliubov approach and the self-consistent time-dependent Hartree-Fock-Bogoliubov approximation. During their time evolution, these quantities exhibit slow or fast oscillations depending on the strength of the shielding interactions. We find that at long time scales the molecular condensate is characterized by nonequilibrium steady-state momentum distribution functions, with depletion, anomalous density and correlations that deviate from their corresponding equilibrium values. We demonstrate that the pair correlations expand diffusively at short times while they spread ballistically at long times.
Quantum Gases (cond-mat.quant-gas)
9 pages, 6 figures
Phys. Rev. A 111, 063315 (2025)
Uncertainty-Aware Machine-Learning Framework for Predicting Dislocation Plasticity and Stress-Strain Response in FCC Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Jing Luo, Yejun Gu, Yanfei Wang, Xiaolong Ma, Jaafar.A El-Awady
Machine learning has significantly advanced the understanding and application of structural materials, with an increasing emphasis on integrating existing data and quantifying uncertainties in predictive modeling. This study presents a comprehensive methodology utilizing a mixed density network (MDN) model, trained on extensive experimental data from literature. This approach uniquely predicts the distribution of dislocation density, inferred as a latent variable, and the resulting stress distribution at the grain level. The incorporation of statistical parameters of those predicted distributions into a dislocation-mediated plasticity model allows for accurate stress-strain predictions with explicit uncertainty quantification. This strategy not only improves the accuracy and reliability of mechanical property predictions but also plays a vital role in optimizing alloy design, thereby facilitating the development of new materials in a rapidly evolving industry.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Deciphering Chiral Superconductivity via Impurity Bound States
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Determining the symmetry of Cooper pairs remains a central challenge in the study of unconventional superconductors, particularly for chiral states that spontaneously break time-reversal symmetry. Here we demonstrate that point-like impurities in chiral superconductors generate in-gap bound states with a distinctive asymmetry: the local density of states at the impurity site vanishes at one bound-state energy, but not at its particle-hole conjugate. We prove this behavior analytically in generic two-dimensional, single-band chiral superconductors, showing it arises from a fundamental interplay between pairing chirality and crystalline rotation symmetry. Our numerical simulations confirm that this diagnostic feature persists in multiband systems and for spatially extended impurities. Our results establish a symmetry-enforced real-space diagnostic for chiral superconductivity at the atomic scale.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
High Temperature Quantum Emission from Covalently Functionalized van der Waals Heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
S. Carin Gavin, Hsun-Jen Chuang, Anushka Dasgupta, Moumita Kar, Kathleen M. McCreary, Sung-Joon Lee, M. Iqbal Bakti Utama, Xiangzhi Li, George C. Schatz, Tobin J. Marks, Mark C. Hersam, Berend T. Jonker, Nathaniel P. Stern
Two-dimensional (2D) transition metal dichalcogenides (TMDs) are attractive nanomaterials for quantum information applications due to single photon emission (SPE) from atomic defects, primarily tungsten diselenide (WSe2) monolayers. Defect and strain engineering techniques have been developed to yield high purity, deterministically positioned SPE in WSe2. However, a major challenge in application of these techniques is the low temperature required to observe defect-bound TMD exciton emission, typically limiting SPE to T<30 K. SPE at higher temperatures either loses purity or requires integration into complex devices such as optical cavities. Here, 2D heterostructure engineering and molecular functionalization are combined to achieve high purity (>90%) SPE in strained WSe2 persisting to over T=90 K. Covalent diazonium functionalization of graphite in a layered WSe2/graphite heterostructure maintains high purity up to T=90 K and single-photon source integrity up to T=115 K. This method preserves the best qualities of SPE from WSe2 while increasing working temperature to more than three times the typical range. This work demonstrates the versatility of surface functionalization and heterostructure design to synergistically improve the properties of quantum emission and offers new insights into the phenomenon of SPE from 2D materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 6 figures
Dynamically emergent correlations in a Brownian gas with diffusing diffusivity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-27 20:00 EDT
Nikhil Mesquita, Satya N. Majumdar, Sanjib Sabhapandit
We study a gas of $ N$ Brownian particles in the presence of a common stochastic diffusivity $ D(t)=B^2(t)$ , where $ B(t)$ represents a one-dimensional Brownian motion at time $ t$ . Starting with all the particles from the origin, the gas expands ballistically. We show that because of the common stochastic diffusivity, the expanding gas gets dynamically correlated, and the joint probability density function of the position of the particles has a conditionally independent and identically distributed (CIID) structure that was recently found in several other systems. The special CIID structure allows us to compute the average density profile of the gas, extreme and order statistics, gap distribution between successive particles, and the full counting statistics (FCS) that describes the probability density function (PDF) $ H(\kappa, t)$ of the fraction of particles $ \kappa$ in a given region $ [-L,L]$ . Interestingly, the position fluctuation of the central particles and the average density profiles are described by the same scaling function. The PDF describing the FCS has an essential singularity near $ \kappa=0$ , indicating the presence of particles inside the box $ [-L,L]$ at all times. Near the upper limit $ \kappa =1$ , the scaling function $ H(\kappa,t)$ has a rather unusual behavior: $ H(\kappa,t)\sim (1-\kappa)^{\beta(t)}$ where the exponent $ \beta(t)$ changes continuously with time. While at early times $ \beta(t)<0$ indicating a divergence of $ H(\kappa,t)$ as $ \kappa\to 1$ , $ \beta(t)$ becomes positive for $ t>t_c$ where $ t_c$ is computed exactly. For $ t>t_c$ , the scaling function $ H(\kappa,t)$ vanishes as $ \kappa\to 1$ , indicating that it is highly unlikely to have all the particles in the interval $ [-L,L]$ . Exactly at $ t=t_c$ , $ \beta=0$ , indicating that the PDF approaches a non-zero constant as $ \kappa\to 1$ . Thus, as a function of $ t$ , the FCS exhibits an interesting shape transition.
Statistical Mechanics (cond-mat.stat-mech)
21 pages, 6 figures
Superconductivity in spin-orbit coupled BaBi$_3$ formed by \textit{in situ} reduction of bismuthate films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Shama, Jordan T. McCourt, Merve Baksi, Gleb Finkelstein, Divine Kumah
Oxygen-scavenging at oxide heterointerfaces has emerged as a powerful route for stabilizing metastable phases that exhibit interesting phenomena, including high-mobility two-dimensional electron gases and high T$ _{c}$ superconductivity. We investigate structural and chemical interactions at the heterointerface formed between Eu metal and the charged-ordered insulator, BaBiO$ _3$ , which leads to emergent superconductivity at 6 K. A combination of X-ray diffraction and electron microscopy measurements shows that oxygen scavenging by the Eu adlayer leads to the formation of EuO$ _x$ and the superconducting intermetallic BaBi$ _3$ . The superconducting state is quasi-two-dimensional, as evidenced by the angle-dependent magnetotransport measurements and current-voltage characteristics. An in-plane upper critical field B$ _{c2}$ significantly exceeding the Pauli paramagnetic limit is observed, possibly reflecting features of Ising superconductivity. The strong spin-orbit coupling at the Bi sites may pave the way for the realization of high-T$ _{c}$ topological superconductivity.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Influence and information in a collective of self-propelled particles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-27 20:00 EDT
While information-theoretic quantities, such as transfer entropy, have been widely adopted to infer causal relationships in collective systems, a critical gap exists: the absence of quantitative evidence directly linking information-theoretic quantities to a physically defined influence. This letter addresses this gap by proposing a modified Vicsek model that enables the calculation of a physically interpretable influence grounded in the angular interactions between particles. Averaged pairwise influences can serve as new order parameters to indicate collective phase transitions. We reveal quantitative relations between information, represented by transfer entropy, and average influence in pairwise and collective interactions. We test three typical methods of partial information decomposition and find that the method based on intrinsic mutual information gives the most appropriate interpretation. Overall, this work provides a model system for quantitative studies of influence and information in complex systems.
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
Energetic and Structural Properties of Two-Dimensional Trapped Mesoscopic Fermi Gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-27 20:00 EDT
Emma K. Laird, Brendan C. Mulkerin, Jia Wang, Matthew J. Davis
We theoretically investigate equal-mass spin-balanced two-component Fermi gases in which pairs of atoms with opposite spins interact via a short-range isotropic model potential. We probe the distinction between two-dimensional and quasi-two-dimensional harmonic confinement by tuning the effective range parameter within two-dimensional scattering theory. Our approach, which yields numerically exact energetic and structural properties, combines a correlated Gaussian basis-set expansion with the stochastic variational method. For systems containing up to six particles, we: 1) Present the ground- and excited-state energy spectra; 2) Study non-local correlations by analysing the one- and two-body density matrices, extracting from these the occupation numbers of the natural orbitals, the momentum distributions of atoms and pairs, and the molecular ‘condensate fraction’; 3) Study local correlations by computing the radial and pair distribution functions. This paper extends current theoretical knowledge on the properties of trapped few-fermion systems as realised in state-of-the-art cold-atom experiments.
Quantum Gases (cond-mat.quant-gas)
25 pages, 9 figures
Confusion-driven machine learning of structural phases of a flexible, magnetic Stockmayer polymer
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Dilina Perera, Samuel McAllister, Joan Josep Cerdà, Thomas Vogel
We use a semi-supervised, neural-network based machine learning technique, the confusion method, to investigate structural transitions in magnetic polymers, which we model as chains of magnetic colloidal nanoparticles characterized by dipole-dipole and Lennard-Jones interactions. As input for the neural network we use the particle positions and magnetic dipole moments of equilibrium polymer configurations, which we generate via replica-exchange Wang–Landau simulations. We demonstrate that by measuring the classification accuracy of neural networks, we can effectively identify transition points between multiple structural phases without any prior knowledge of their existence or location. We corroborate our findings by investigating relevant, conventional order parameters. Our study furthermore examines previously unexplored low-temperature regions of the phase diagram, where we find new structural transitions between highly ordered helicoidal polymer configurations.
Soft Condensed Matter (cond-mat.soft)
Electric field-induced clustering in nanocomposite films of highly polarizable inclusions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Elshad Allahyarov, Hartmut Löwen
A nanocomposite film containing highly polarizable inclusions in a fluid background is explored when an external electric field is applied perpendicular to the planar film. For small electric fields, the induced dipole moments of the inclusions are all polarized in field direction, resulting in a mutual repulsion between the inclusions. Here we show that this becomes qualitatively different for high fields: the total system self-organizes into a state which contains both polarizations, parallel and antiparallel to the external field such that a fraction of the inclusions is counter-polarized to the electric field direction. We attribute this unexpected counter-polarization to the presence of neighboring dipoles which are highly polarized and locally revert the direction of the total electric field. Since dipoles with opposite moments are attractive, the system shows a wealth of novel equilibrium structures for varied inclusion density and electric field strength. These include fluids and solids with homogeneous polarizations as well as equilibrium clusters and demixed states with two different polarization signatures. Based on computer simulations of a linearized polarization model, our results can guide the control of nanocomposites for various applications, including sensing external fields, directing light within plasmonic materials, and controlling the functionality of biological membranes.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
12 pages, 7 figures
Journal of Colloid and Interface Science 668 (2024) 587-598
Electronic conduction in copper-graphene composites with functional impurities
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Kishor Nepal, Ridwan Hussein, Yahya Al-Majali, David Drabold
Coal-derived graphene-like material and its addition to FCC copper are investigated using ab initio plane wave density functional theory (DFT). We explore ring disorder in the sp2 carbon, and functional impurities such as oxides (-O), and hydroxides (-OH) that are common in coal-derived graphene. The electronic density of states analysis revealed localized states near the Fermi level, with functional groups contributing predominantly to states below the Fermi level, while carbon atoms in non-hexagonal rings contributed mainly to states above it. The functionalization of graphene induces charge localization while ring disorder disrupts the continuous flow of electrons. By projecting the electronic conductivity along specific spatial directions, we find that both the crystal orientation and the graphene purity significantly influence the anisotropy and magnitude of electronic transport in the composites. This study implicitly highlights the importance of structural stress to obtain improved electrical conductivity in such composites.
Materials Science (cond-mat.mtrl-sci)
High-Throughput Mapping of Magnetic Properties via the on-the-fly XMCD spectroscopy in a Combinatorial Fe-Co-Ni Film
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Y. Yamasaki, N. Sasabe, Y. Ishii, Y. Sekiguchi, A. Sumiyoshiya, Y. Tanimoto, Y. Kotani, T. Nakamura, H. Nomura
High-throughput X-ray magnetic circular dichroism (XMCD) spectroscopy was conducted on Fe-Co-Ni compositionally graded films to systematically analyze the variation of magnetic properties as a function of composition. On-the-fly XMCD measurement enabled rapid spectral acquisition. Measurement time was reduced approximately tenfold compared to conventional stepwise methods, while maintaining high precision. The obtained XMCD spectra were processed using the Savitzky-Golay denoising technique, and element-specific magnetic properties were extracted using XMCD sum rules. By mapping the orbital and spin magnetic moments across the composition gradient, we identified key regions exhibiting enhanced soft magnetic properties. This study demonstrates the effectiveness of high-throughput synchrotron-based spectroscopy for accelerating materials discovery and optimizing functional magnetic materials.
Materials Science (cond-mat.mtrl-sci)
The electronic structures, magnetic transition and Fermi surface instability of room-temperature altermagnet KV${2}$Se${2}$O
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
Yuanji Xu, Huiyuan Zhang, Maoyuan Feng, Fuyang Tian
Altermagnetism has recently emerged as a distinct and fundamental class of magnetic order. Exploring its interplay with quantum phenomena such as unconventional superconductivity, density-wave instabilities, and many-body effects represents a compelling frontier. In this work, we theoretically confirm the presence of high-temperature metallic altermagnetism in KV$ _2$ Se$ _2$ O. We demonstrate that the anomalous metal-insulator-metal transition arises from a Lifshitz transition associated with Fermi surface reconstruction. The previously reported spin-density wave gap is found to lie below the Fermi level in our study and is now recognized to be attributed to the V-shaped density of states, originating from orbital-selective and sublattice-resolved half-metal-like behavior on a specific V atom. Furthermore, we identify the instability from the nesting of spin-momentum-locked two-dimensional Fermi surfaces, which induces the SDW state. These findings position KV$ _2$ Se$ _2$ O as a promising platform for investigating the interplay among altermagnetism, unconventional superconductivity, and density-wave order.
Strongly Correlated Electrons (cond-mat.str-el)
All-electric control of skyrmion-bimeron transition in van der Waals heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Lan Bo, Songli Dai, Xichao Zhang, Masahito Mochizuki, Xiaohong Xu, Zean Tian, Yan Zhou
Two-dimensional van der Waals materials offer a versatile platform for manipulating atomic-scale topological spin textures. In this study, using first-principles and micromagnetic calculations, we demonstrate a reversible transition between magnetic skyrmions and bimerons in a MoTeI/In_2Se_3 multiferroic heterostructure. The physical origin lies in the reorientation of the easy axis of magnetic anisotropy, triggered by the reversal of ferroelectric polarization. We show that the transition operates effectively under both static and dynamic conditions, exhibiting remarkable stability and flexibility. Notably, this transition can be achieved entirely through electric control, without requiring any external magnetic field. Furthermore, we propose a binary encoding scheme based on the skyrmion-bimeron transition, presenting a promising path toward energy-efficient spintronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
11 pages, 5 figures
Modeling active nematics via the nematic locking principle
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Kevin A. Mitchell, Md Mainul Hasan Sabbir, Sean Ricarte, Brandon Klein, Daniel A. Beller
Active nematic systems consist of rod-like internally driven subunits that interact with one another to form large-scale coherent flows. They are important examples of far-from-equilibrium fluids, which exhibit a wealth of nonlinear behavior. This includes active turbulence, in which topological defects braid around one another in a chaotic fashion. One of the most studied examples of active nematics is a dense two-dimensional layer of microtubules, crosslinked by kinesin molecular motors that inject extensile deformations into the fluid. Though numerous studies have modeled microtubule-based active nematics, no consensus has emerged on how to fully capture the features of the experimental system. To better understand the foundations for modeling this system, we propose a fundamental principle we call the nematic locking principle: individual microtubules cannot rotate without all neighboring microtubules also rotating. Physically, this is justified by the high density of the microtubules, their elongated nature, and their corresponding steric interactions. We assert that nematic locking holds throughout the majority of the material but breaks down in the neighborhood of topological defects and other regions of low density. We derive the most general nematic transport equation consistent with this principle and also derive the most general term that violates it. We examine the standard Beris-Edwards approach used to model this system and show that it violates nematic locking throughout the majority of the material. We then propose a modification to the Beris-Edwards model that enforces nematic locking nearly everywhere. This modification shuts off fracturing except in regions where the order parameter is reduced. The resulting simulations show strong nematic locking throughout the bulk of the material, consistent with experimental observation.
Soft Condensed Matter (cond-mat.soft), Chaotic Dynamics (nlin.CD)
Quantitative structure determination from experimental four-dimensional scanning transmission electron microscopy via the scattering matrix
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Emmanuel W.C. Terzoudis-Lumsden, Alireza Sadri, Matthew Weyland, Laure Bourgeois, Stephanie M. Ribet, Georgios Varnavides, Colin Ophus, Timothy C. Petersen, Scott D. Findlay
Considerable inroads have recently been made on algorithms to determine the sample potential from four-dimensional scanning transmission electron microscopy data from thick samples where multiple scattering cannot be neglected. This paper further develops the scattering matrix approach to such structure determination. Through simulation, we demonstrate how this approach can be modified to better handle partial spatial coherence, unknown probe defocus, and information from the dark field region. By combining these developments we reconstruct the electrostatic potential of a monolithic SrTiO$ _3$ crystal showing good quantitative agreement with the expected structure.
Materials Science (cond-mat.mtrl-sci), Instrumentation and Detectors (physics.ins-det)
24 pages, 9 figures
Ferroelectricity in 6 Angstrom-Thick Two-dimensional Ga$_2$O$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Tong Jiang (1,2,4), Han Chen (1,2,4), Yubo Yuan (1,2,4), Xiang Xu (1,2,4), Junwei Cao (1,2,4), Hao Wang (2,4), Xuechun Sun (1,2,4), Junshuai Li (2,4), Yaqing Ma (1,2,4), Huaze Zhu (2,4), Wenbin Li (2,4), Wei Kong (2,3,4,5) ((1) School of Materials Science and Engineering, Zhejiang University, Hangzhou, China, (2) Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, China, (3) Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, China, (4) School of Engineering, Westlake University, Hangzhou, Zhejiang, China, (5) Westlake Institute for Optoelectronics, Hangzhou, China)
Atomic-scale ferroelectric thin films hold great promise for high-density, low-power applications but face stability and voltage scaling challenges at extreme thinness. Here, we demonstrate ferroelectricity in single-crystalline two-dimensional (2D) Ga$ _2$ O$ _3$ , an ultra-wide-bandgap semiconductor, at just 6 angstrom thickness, exhibiting exceptional retention and thermal stability. We show that epitaxial beta-Ga$ _2$ O$ _3$ can be exfoliated down to a half-unit cell thickness via a self-limiting mechanism, enabling a biaxial strain-induced phase transition into a novel ferroelectric layered structure. Strain modulation enables the reduction of polarization switching voltage to 0.8 V, meeting CMOS voltage scaling requirements. Theoretical calculations reveal that switching is driven by covalent bond reconstruction, effectively countering depolarization and enhancing stability. Additionally, we integrate ferroelectric 2D Ga$ _2$ O$ _3$ onto silicon using a low-temperature, back-end-of-line-compatible process. This work advances the exploration of sub-nanometer ferroelectrics, paving the way for high-density, low-power, non-volatile applications seamlessly integrated with advanced silicon technology.
Materials Science (cond-mat.mtrl-sci)
38 pages, 13 figures
Theory of the Anderson transition in three-dimensional chiral symmetry classes: Connection to type-II superconductors
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-06-27 20:00 EDT
Phase transitions governed by topological defects constitute a cornerstone of modern physics. Two-dimensional (2D) Anderson transitions in chiral symmetry classes are driven by the proliferation of vortex-antivortex pairs – a mechanism analogous to the Berezinskii-Kosterlitz-Thouless (BKT) transition in the 2D XY model. In this work, we extend this paradigm to three-dimensional (3D) chiral symmetry classes, where vortex loops emerge as the key topological defects governing the Anderson transition. By deriving the dual representation of the 3D nonlinear sigma model for the chiral unitary class, we develop a mean-field theory of its Anderson transition and elucidate the role of 1D weak band topology in the Anderson transition. Strikingly, our dual representation of the 3D NLSM in the chiral symmetry class uncovers its connection to the magnetostatics of 3D type-II superconductors. The metal-to-quasilocalized and quasilocalized-to-insulating transitions in 3D chiral symmetry class share a unified theoretical framework with the normal-to-mixed and mixed-to-superconducting transitions in 3D type-II superconductors under an external magnetic field, respectively.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Superconductivity (cond-mat.supr-con)
18 pages, 2 figures
Microphase Separation Controls the Dynamics of Associative Vitrimers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Rahul Karmakar, Abhishek S. Chankapure, Srikanth Sastry, Sanat K. Kumar, Tarak K. Patra
Vitrimers are a class of polymers characterized by dynamic covalent networks, where specific monomer units, which are know as stickers, form reversible crosslinks that enable network rearrangement without loss of overall connectivity. The conventional wisdom is that the sticker dynamics control chain relaxation behavior, and hence the mechanical properties of associative vitrimers where the number of crosslinked sticker pairs is precisely constant over time. Instead, here we show that the chemical differences between sticker groups and nonsticky chain monomers can cause them to microphase separate. Under these conditions, the slow exchange of a sticker from one microphase to an adjacent one controls relaxation behavior. Controlling sticker aggregation is thus a key to tailoring the properties of these polymers with immediate relevance to a circular polymer economy.
Soft Condensed Matter (cond-mat.soft)
Nonsymmorphic symmetry-enforced hourglass fermions and Rashba-Dresselhaus interaction in BiInO$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Ramsamoj Kewat, Nirmal Ganguli
In this study, we investigate the spin texture of the hourglass fermions band network in BiInO$ _3$ using density functional theory (DFT) and symmetry analysis. Hourglass fermions are of interest in spintronics due to their unique and robust band structure, as well as their potential applications in novel electronic devices. BiInO$ _3$ exhibits non-symmorphic crystal symmetries, such as glide reflection and glide rotational symmetry, influencing its electronic properties. Through symmetry analysis, we explore the band crossings and spin textures along specific high-symmetry paths in the Brillouin zone. Our results reveal a fascinating hourglass-shaped band dispersion and spin polarisation governed by symmetry operations and spin-orbit interaction. We analyse the spin-splitting mechanisms, including Dresselhaus and Rashba spin-orbit interactions, and suggest potential applications for spin-based devices. This study sheds light on the role of symmetry in crystals for fascinating spin properties of hourglass fermions in non-symmorphic materials, offering insights for future developments in spintronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Efficient Band Structure Unfolding with Atomic-centered Orbitals: General Theory and Application
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Jingkai Quan, Nikita Rybin, Matthias Scheffler, Christian Carbogno
Band structure unfolding is a key technique for analyzing and simplifying the electronic band structure of large, internally distorted supercells that break the primitive cell’s translational symmetry. In this work, we present an efficient band unfolding method for atomic orbital (AO) basis sets that explicitly accounts for both the non-orthogonality of atomic orbitals and their atom-centered nature. Unlike existing approaches that typically rely on a plane-wave representation of the (semi-)valence states, we here derive analytical expressions that recasts the primitive cell translational operator and the associated Bloch-functions in the supercell AO basis. In turn, this enables the accurate and efficient unfolding of conduction, valence, and core states in all-electron codes, as demonstrated by our implementation in the all-electron ab initio simulation package FHI-aims, which employs numeric atom-centered orbitals. We explicitly demonstrate the capability of running large-scale unfolding calculations for systems with thousands of atoms and showcase the importance of this technique for computing temperature-dependent spectral functions in strongly anharmonic materials using CuI as example.
Materials Science (cond-mat.mtrl-sci)
Electronic and Thermoelectric Properties of Molecular Junctions Incorporating Organometallic Complexes: Implications for Thermoelectric Energy Conversion
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Joseane Santos Almeida, Sergio González Casal, Hassan Al Sabea, Valentin Barth, Gautam Mitra, Vincent Delmas, David Guérin, Olivier Galangau, Tiark Tiwary, Thierry Roisnel, Vincent Dorcet, Lucie Norel, Colin Van Dyck, Elke Scheer, Dominique Vuillaume, Jérôme Cornil, Stéphane Rigaut, Karine Costuas
The electronic and thermoelectric properties of molecular junctions formed from iron and ruthenium metal-acetylide were studied using complementary experimental techniques and quantum chemical simulations. We performed physical characterizations of single-molecule and self-assembled monolayer junctions of the same molecules that allowed meaningful comparisons between the Ru and Fe adducts. In the case of the Fe-containing junctions, two distinct oxidation states are present. These junctions exhibit one of the highest Seebeck coefficients (S ca. 130 {\mu}V/K) reported to date for similar systems paired with broad electric conductance distribution and limited thermal conductance. As a result, the experimental thermoelectric figure of merit ZT for Fe-containing junctions reaches up to 0.4 for junctions with relatively high conductance. This is one of the highest ZT values reported for molecular systems at room temperature.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Reevaluating the electrical impact of atomic carbon impurities in MoS2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
James Ramsey, Faiza Alhamed, Jonathan P. Goss, Patrick R. Briddon, Mark J. Rayson
Transition metal dichalcogenides, a family of two-dimensional compounds, are of interest for a range of technological applications. MoS2, the most researched member of this family, is hexagonal, from which monolayers may be isolated. Under ambient conditions and during growth/processing, contamination by impurities can occur, of which carbon is significant due to its presence in the common growth techniques. We have performed extensive computational investigations of carbon point defects, examining substitutional and interstitial locations. Previously unreported thermodynamically stable configurations, four-fold co-ordinated mono-carbon and di-carbon substitutions of Mo, and a complex of carbon substitution of sulfur bound to interstitial sulfur have been identified. We find no evidence to support recent assertions that carbon defects are responsible for electrical doping of MoS2, finding all energetically favorable forms have only deep charge transition levels and would act as carrier traps. To aid unambiguous identification of carbon defects, we present electronic and vibrational data for comparison with spectroscopy.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 4 figures, 4 tables
Rabi-induced localization and resonant delocalization of a binary condensate in a spin-asymmetric quasiperiodic potential
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-27 20:00 EDT
Swarup K. Sarkar, Sh. Mardonov, E. Ya. Sherman, Pankaj K. Mishra
We theoretically investigate the ground state and dynamics of a Rabi-coupled pseudospin-1/2 Bose-Einstein condensate, where only one spin component is subjected to an external potential. We show that in the quasiperiodic potential the Rabi coupling induces localization between the components as it is raised above the threshold value. Interestingly, the localization is mutually induced by both components for the quasiperiodic confinement, whereas for a harmonic trap the localization is induced in the potential-free component by interaction with that confined in the potential. Further, we explore the condensate dynamics by implementing a periodic driving of the Rabi frequency, where various frequency-dependent delocalization patterns, such as double (triple)-minima, tree-(parquet)-like, and frozen distributions with a correlated propagation of different spin populations are observed in the condensate density. These features pave the way to control the condensate mass and spin density patterns, both in the stationary and dynamical realizations.
Quantum Gases (cond-mat.quant-gas)
15pages, 15figures
Electrical Characterization of hexagonal SiGe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Isabelle Bollier, Federico Balduini, Marilyne Sousa, Marco Vettori, Wouter H.J. Peeters, Erik P.A.M. Bakkers, Heinz Schmid
We report electrical measurements on hexagonal silicon-germanium (hex-SiGe), a group IV alloy with direct bandgap. Electrical contacts are formed by metal alloying and doping is achieved using ion implantation. The metastable hex-SiGe phase is successfully recovered after implantation by solid phase recrystallization. Independent of the metal used, contacts on n-type resulted in Schottky barriers due to Fermi level pinning of hex-SiGe. Overall, this constitutes a first step towards use of hex-SiGe for optoelectronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Thermoelectric Fingerprinting of Bloch- and Néel-type Skyrmions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Christopher E. A. Barker, Elias Saugar, Katharina Zeissler, Robert Puttock, Petr Klapetek, Olga Kazakova, Christopher H. Marrows, Oksana Chubykalo-Fesenko, Craig Barton
Magnetic skyrmions are nanoscale spin textures that exhibit topological stability, which, along with novel thermal and electrical transport properties, make them the ideal candidates for a variety of novel technological applications. Accessing the skyrmion spin texture at the nanoscale and understanding its interaction with local thermal gradients is essential for engineering skyrmion-based transport phenomena. However, direct experimental insight into the local thermoelectric response of single skyrmions remains limited. To address this, we employ scanning thermoelectric microscopy~(SThEM) to probe the nanoscale thermoelectric response from a single skyrmion. By mapping the local thermoelectric voltage with nanoscale precision, we reveal a unique spatially resolved response that is the convolution of the underlying spin texture of the skyrmion and its interaction with the highly localised thermal gradient originating from the heated probe. We combine this with thermoelectric modelling of a range of skyrmion spin textures to reveal unique thermoelectric responses and allow the possibility of SThEM to be used as a tool to distinguish nanoscale spin textures. These findings provide fundamental insights into the interaction of topologically protected spin textures with local thermal gradients and the resultant spin transport. We demonstrate a novel route to characterise nanoscale spin textures, accelerating the material optimisation cycle, while also opening the possibility to harness skyrmions for spin caloritronics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
20 pages 4 figures
AC-driven Spin Valves: Capacitive Behavior and Resonator Applications
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
This study explores the time-dependent spin transport phenomena in magnetic heterostructures under alternating currents (AC), advancing the relatively underdeveloped field of alternating spintronics. Employing a time-dependent spin diffusion model, we show that the interplay of AC frequencies and spin relaxation times reveals significant differences in spin accumulation patterns compared to conventional direct current (DC) scenarios. Of particular interest is the emergence of capacitive-like impedance in a spin valve under AC conditions, which is especially pronounced in antiparallel spin configurations. These findings open up possibilities for developing high-frequency spintronic devices, including the proposed “spin resonator”, which functions like a standard LC resonator but without a traditional capacitor.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
6 pages, 4 figures, 1 appendix section
Spin Liquid Mimicry in the Hydroxide Double Perovskite CuSn(OH)$_6$ Induced by Correlated Proton Disorder
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
Anton A. Kulbakov, Ellen Häußler, Kaushick K. Parui, Nikolai S. Pavlovskii, Aswathi Mannathanath Chakkingal, Sergey A. Granovsky, Sebastian Gaß, Laura Teresa Corredor Bohórquez, Anja U. B. Wolter, Sergei A. Zvyagin, Yurii V. Skourski, Vladimir Yu. Pomjakushin, Inés Puente-Orench, Darren C. Peets, Thomas Doert, Dmytro S. Inosov
The face-centered-cubic lattice is composed of edge-sharing tetrahedra, making it a leading candidate host for strongly frustrated magnetism, but relatively few face-centered frustrated materials have been investigated. In the hydroxide double perovskite \cusnoh, magnetic frustration of the Cu$ ^{2+}$ quantum spins is partially relieved by strong Jahn-Teller distortions. Nevertheless, the system shows no signs of long-range magnetic order down to 45,mK and instead exhibits broad thermodynamic anomalies in specific heat and magnetization, indicating short-range dynamical spin correlations, – ,a behavior typical of quantum spin liquids. We propose that such an unusual robustness of the spin-liquid-like state is a combined effect of quantum fluctuations of the quantum spins $ S=\frac{1}{2}$ , residual frustration on the highly distorted face-centered Cu$ ^{2+}$ sublattice, and correlated proton disorder. Similar to the disorder-induced spin-liquid mimicry in YbMgGaO$ _4$ and herbertsmithite, proton disorder destabilizes the long-range magnetic order by introducing randomness into the magnetic exchange interaction network. However, unlike the quenched substitutional disorder on the magnetic sublattice, which is difficult to control, proton disorder can in principle be tuned through pressure-driven proton ordering transitions. This opens up the prospect of tuning the degree of disorder in a magnetic system to better understand its influence on the magnetic ground state.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 3 figures
Confined acoustic phonons in CsPbI3 nanocrystals explored by resonant Raman scattering on excitons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Carolin Harkort, Ina V. Kalitukha, Nataliia E. Kopteva, Mikhail O. Nestoklon, Serguei V. Goupalov, Lucien Saviot, Dennis Kudlacik, Dmitri R. Yakovlev, Elena V. Kolobkova, Maria S. Kuznetsova, Manfred Bayer
Optical properties of the lead halide perovskites nanocrystals are controlled by confined excitons and rich spectrum of confined acoustic and optical phonons. We study experimentally and theoretically the exciton-phonon interaction in CsPbI3 perovskite nanocrystals embedded in a glass matrix. Energies of phonon modes allowed by selection rules are detected by resonant Raman scattering for nanocrystals with sizes of 4-13 nm, covering exciton energies of 1.72-2.25 eV. While optical phonon energies remain size-independent, the energies of confined acoustic phonons increase in smaller nanocrystals. Acoustic phonons are modeled within the continuum approximation using elastic constants computed by density functional theory. The model provides the energy spectra of confined phonons for nanocrystals of various shapes (cube, sphere, spheroid), crystal symmetries (orthorhombic and tetragonal), and sizes. Exciton confinement restricts efficient coupling to only few phonon modes observable in Raman spectra. By comparing experimental data with model predictions, we conclude that the nanocrystals in our samples predominantly have spherical or spheroidal shapes.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Wurtzite Boron Nitride as a potential defects host
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
M. Silvetti, M. Pouyot, E. Cannuccia
Wurtzite boron nitride (wBN) is a polymorph of boron nitride and serves as an intermediate phase in the transition from hBN to cBN under high pressure and temperature conditions. Owing to these extreme synthesis conditions, wBN likely inherits defects from hexagonal phase, where bright and stable single-photon emitters have been observed in both the visible and ultraviolet spectral ranges. While hBN and cubic BN (cBN) have been extensively studied for hosting quantum emitters, wBN remains comparatively unexplored. In this work, we use first-principles hybrid DFT calculations to investigate the formation energies and electronic structures of key native point defects in wBN, including boron and nitrogen vacancies, antisites, and carbon impurities, across various charge states. Our results reveal the potential of wBN as a robust platform for optically active defects. These properties make it a promising candidate for quantum technologies operating under extreme conditions. This study lays the groundwork for future experimental efforts in defect identification and engineering in wBN.
Materials Science (cond-mat.mtrl-sci)
An analysis of derivative absorption spectroscopy of multiferroic bismuth ferrite materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
The probability density function (PDF) and cumulative density function (CDF) of bulk BiFeO3, nanostructured BiFeO$ _3$ , and thick film of BiFeO$ _{2.85}$ were studied in detail based on their experimental absorption data. The goal of this study was to investigate the electronic transitions and the Urbach tail band in three samples of the magnetoelectric multiferroic BiFeO$ _3$ . The PDF and CDF functions were derived from the absorption data of these substances in the UV-visible-NIR region of light spectrum. For the BiFeO$ _3$ -based materials, charge transfer (p-d and/or p-p) transitions in the energy range of 2.5 eV to 5.5 eV were identified through PDF and CDF analysis. Furthermore, spin-orbit and electron-lattice interactions along with a low-symmetry crystal field cause two doubly degenerate d-d transitions of Fe$ ^{3+}$ ions in the FeO$ _6$ octahedra of the BiFeO$ _3$ samples to occur between 1.5 eV and 2.5 eV. Additionally, the BiFeO3-based materials exhibited strong direct and weak indirect transitions near the band edge, which point to a complex band structure of BiFeO$ _3$ . Finally, the energy of the defect-induced Urbach tail band was directly calculated by examining the CDF function of the materials, yielding estimated values of approximately 0.40 eV, 0.31 eV, and 0.33 eV for the bulk, nanostructured, and film BiFeO$ _3$ samples, respectively.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
20 pages. 6 figures, 1 table, Submitted to PRB (# BF15356)
Diverse polymorphs and phase transitions in van der Waals In$_2$Se$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Mingfeng Liu, Jiantao Wang, Peitao Liu, Qiang Wang, Zhibo Liu, Yan Sun, Xing-Qiu Chen
Van der Waals In$ _2$ Se$ _3$ has garnered significant attention due to its unique properties and wide applications associated with its rich polymorphs and polymorphic phase transitions. Despite extensive studies, the vast complex polymorphic phase space remains largely unexplored, and the underlying microscopic mechanism for their phase transformations remains elusive. Here, we develop a highly accurate, efficient, and reliable machine-learning potential (MLP), which not only facilitates accurate exploration of the intricate potential energy surface (PES), but also enables us to conduct large-scale molecular dynamics (MD) simulations with first-principles accuracy. We identify the accurate structure of the $ \beta’’$ polymorph and uncover several previously unreported $ \beta’$ polymorph variants exhibiting dynamic stability and competing energies, which are elucidated by characteristic flat imaginary phonon bands and the distinctive Mexican-hat-like PES in the $ \beta$ polymorph. Through the MLP-accelerated MD simulations, we directly observe the polymorphic phase transformations among the $ \alpha$ , $ \beta$ , $ \beta’$ , and $ \beta’’$ polymorphs under varying temperature and pressure conditions, and build for the first time an ab initio temperature-pressure phase diagram, showing good agreement with experiments. Furthermore, our MD simulations reveal a novel strain-induced reversible phase transition between the $ \beta’$ and $ \beta’’$ polymorphs. This work not only unveils diverse polymorphs in van der Waals In$ _2$ Se$ _3$ , but also provides crucial atomic insights into their phase transitions, opening new avenues for the design of novel functional electronic devices.
Materials Science (cond-mat.mtrl-sci)
32 pages, 20 figures (including Supplementary Information)
Crystallization of metallic glass as a grain-boundary nucleated process: experimental and theoretical evidence for the grain structure of metallic glasses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Experimental DSC and Avrami curves for the crystallization of metallic glasses demonstrate nucleation at grain boundaries and thus indicate their grain structure, which refutes the generally accepted idea of glass as a homogeneous frozen liquid obtained as a result of avoiding crystallization. Under certain conditions, this nucleation mechanism results in the appearance of two-peak DSC curves and three-step Avrami plots which are observed experimentally. To clarify these conditions, isothermal and non-isothermal surface-nucleated crystallization of a spherical particle is considered within the framework of a simple analytical model of nucleation and growth.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)
23 pages, 9 figures
Observing Laughlin’s pump using quantized edge states in graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Bjarke S. Jessen, Maëlle Kapfer, YuhaoZhao, Kenji Watanabe, Takashi Taniguchi, Cory R. Dean, Oded Zilberberg
Laughlin’s thought experiment of quantized charge pumping is central to understanding the integer quantum Hall effect (IQHE) and the topological origin of its conductance quantization. Its direct experimental observation, however, has been hindered by the difficulty of realizing clean electronic edges. We address this by fabricating ultra-small, lithographically defined contacts on graphene. This creates a Corbino-equivalent system, with well-confined inner edge states. Crucially, the small contact size induces strong energy quantization of the edge states. This quantization allows us to directly resolve the spectral flow associated with Laughlin’s pump. By tracing the finite-size resonances of the inner edge, we observe clear oscillations in conductance as a function of magnetic field and carrier density. The oscillation period scales with contact size, consistent with quantized charge transfer. Thus, our results provide a direct observation of the spectral flow underlying Laughlin’s pump. The simplicity of the graphene platform makes this approach scalable and robust for exploring fundamental topological effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Anomalous refractive index modulation and giant birefringence in 2D ferrielectric CuInP$_2$S$_6$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Houssam El Mrabet Haje, Roald J. H. van der Kolk, Trent M. Kyrk, Mazhar N. Ali
2D ferroelectric (FE) materials have opened new opportunities in non-volatile memories, computation and non-linear optics due to their robust polarization in the ultra-thin limit and inherent flexibility in device integration. Recently, interest has grown in the use of 2D FEs in electro-optics, demanding the exploration of their electronic and optical properties. In this work, we report the discovery of an unprecedented anomalous thickness-dependent change in refractive index, as large as $ \delta n$ $ \sim$ 23.2$ %$ , in the 2D ferrielectric CuInP$ 2$ S$ 6$ , far above the ultra-thin limit, and at room temperature. Additionally, we observe a giant birefringence in the blue-ultraviolet regime, with a maximum $ \vert n{OOP} - n{IP}\vert$ $ \sim$ 1.24 at $ t \sim$ 22 nm and $ \lambda$ = 339.5 nm. We relate changes in CuInP$ _2$ S$ _6$ optical constants to changes in the Cu(I) FE polarization contribution, influenced by its ionic mobility, opening the door to electronic control of its optical response for use in photonics and electro-optics.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics)
12 pages main text (34 pages total), 5 main text figures (14 figures total)
Molecular motion at the experimental glass transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-27 20:00 EDT
Romain Simon, Jean-Louis Barrat, Ludovic Berthier
We propose a novel strategy to study numerically the glass transition of molecular fluids. Our approach combines the construction of simple yet realistic models with the development of Monte Carlo algorithms to accelerate equilibration and sampling. Inspired by the well-studied ortho-terphenyl glass-former, we construct a molecular model with an analogous triangular geometry and construct a `flip’ Monte Carlo algorithm. We demonstrate that the flip Monte Carlo algorithm achieves a sampling speedup of about $ 10^9$ at the experimental glass transition temperature $ T_g$ . This allows us to systematically analyze the equilibrium structure and molecular dynamics of the model over a temperature regime previously inaccessible. We carefully compare the observed physical behavior to earlier studies that used atomistic models. In particular, we find that the glass fragility and the departure from the Stokes-Einstein relation are much closer to experimental observations. We characterize the development and temperature evolution of spatial correlations in the relaxation dynamics, using both orientational and translational degrees of freedom. Excess wings emerge at intermediate frequencies in dynamic rotational spectra, and we directly visualize the corresponding molecular motion near $ T_g$ . Our approach can be generalized to a number of molecular geometries and paves the way to a complete understanding of how molecular details may affect more universal physical aspects characterizing molecular liquids approaching their glass transition.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Soft Condensed Matter (cond-mat.soft)
16 pages, 13 figures
Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-27 20:00 EDT
Markus Greiner, Olaf Mandel, Tilman Esslinger, Theodor W Hänsch, Immanuel Bloch
For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.
Quantum Gases (cond-mat.quant-gas)
8 pages, 6 figures
Nature, 415, 39-44 (2002)
Kondo-Peierls transition with nonsymmorphic zone boundary gap formation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
Kazumasa Hattori, Hiroaki Kusunose
We study nonsymmorphic space group symmetry breakings in correlated electron systems. Under nonsymmorphic symmetry, it is well known that there are degeneracies in the electronic Bloch states at the Brillouin zone boundaries. When the system undergoes a phase transition into an ordered phase with breaking the nonsymmorphic symmetry, the degeneracy is lifted. This happens even when the order parameter is uniform. We point out that this general feature leads to various {\it uniform} Peierls transition in nonsymmorphic systems. In particular, we show that such mechanism of the Peierls gap formation can be realized accompanying with uniform anisotropic Kondo singlet formations. This explains the hidden electric order observed in CeCoSi.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages and 4 figures
Characterization of Morphology Evolution in a Polymer-Clay Nanocomposite using Multiscale Simulations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
Parvez Khana, Ankit Patidara, Gaurav Goel
Molecular simulations provide an effective route for investigating morphology evolution and structure-property relationship in polymer-clay nanocomposites (PCNCs) incorporating layered silicates like montmorillonite (MMT), an important class of materials that show a significant enhancement over the constituent polymer for several properties. However, long relaxation times and large system size requirements limit the application to systems of practical interest. In this work, we have developed a coarse-grained (CG) model of organically modified MMT (oMMT) compatible with the MARTINI force field, a chemically-specific interaction model with high transferability. The dispersive and polar components of cleavage energy, basal spacing, and mechanical properties of MMT with tetramethylammonium (TMA) as intergallery ions were used to obtain a rational estimate for clay particle MARTINI bead types in accordance with the polarity of the functional group. The CG model provided accurate concurrent estimates for the structural, thermodynamic, and dynamical properties of PE in a PE/TMA-MMT PCNC, with less than 4% deviation from all atom (AA) simulations. The slow clay-induced redistribution of the PE-b-PEG block copolymer in the PCNCs was investigated using the developed CG model, with conformational changes occurring over a microsecond timescale. The preferential interaction coefficient and cluster analysis of individual blocks of PE-b-PEG were used to study the effect of clay arrangement (exfoliated versus tactoid) on copolymer reorientation and assembly at the clay surface. We find that the oMMT coated with PE-b-PEG acts as a neutral surface (small difference in polymer-polymer and polymer-oMMT+PE-b-PEG enthalpic interactions) and the primary influence of the nanofiller is a result of confinement and steric effect of the clay sheets on the PE chains.
Soft Condensed Matter (cond-mat.soft)
Computational Design of Two-Dimensional MoSi$_2$N$_4$ Family Field-Effect Transistor for Future Ångström-Scale CMOS Technology Nodes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Che Chen Tho, Zongmeng Yang, Shibo Fang, Shiying Guo, Liemao Cao, Chit Siong Lau, Fei Liu, Shengli Zhang, Jing Lu, L. K. Ang, Lain-Jong Li, Yee Sin Ang
Advancing complementary metal-oxide-semiconductor (CMOS) technology into the sub-1-nm angström-scale technology nodes is expected to involve alternative semiconductor channel materials, as silicon transistors encounter severe performance degradation at physical gate lengths below 10 nm. Two-dimensional (2D) semiconductors have emerged as strong candidates for overcoming short-channel effects due to their atomically thin bodies, which inherently suppress electrostatic leakage and improve gate control in aggressively scaled field-effect transistors (FETs). Among the growing library of 2D materials, the MoSi$ _2$ N$ _4$ family – a synthetic septuple-layered materials – has attracted increasing attention for its remarkable ambient stability, suitable bandgaps, and favorable carrier transport characteristics, making it a promising platform for next-generation transistors. While experimental realization of sub-10-nm 2D FETs remains technologically demanding, computational device simulation using first-principles density functional theory combined with nonequilibrium Green’s function transport simulations provide a powerful and cost-effective route for exploring the performance limits and optimal design of ultrascaled FET. This review consolidates the current progress in the computational design of MoSi$ _2$ N$ _4$ family FETs. We review the physical properties of MoSi$ _2$ N$ _4$ that makes them compelling candidates for transistor applications, as well as the simulated device performance and optimization strategy of MoSi$ _2$ N$ _4$ family FETs. Finally, we identify key challenges and research gaps, and outline future directions that could accelerate the practical deployment of MoSi$ _2$ N$ _4$ family FET in the angström-scale CMOS era.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
27 pages, 11 figures
Few-body bound states of bosonic mixtures in two-dimensional optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-06-27 20:00 EDT
Matias Volante-Abovich, Felipe Isaule, Luis Morales-Molina
We study the formation of bound states in a binary mixture of a few bosons in square optical lattices. Using the exact diagonalization method, we find that bound clusters of all available bosons can form. We provide a comprehensive numerical examination of these bound states for a wide range of repulsive intraspecies and attractive interspecies interactions. In contrast to binary mixtures in one-dimensional chains, we reveal that the binding energy of the clusters shows a non-monotonic dependence on the interspecies interaction strengths for small tunneling rates, developing a local minimum for intermediate attractive interactions. The findings of this work highlight the difference between the binding mechanisms of binary bosonic mixtures in one- and higher-dimensional lattices.
Quantum Gases (cond-mat.quant-gas)
10 pages, 9 figures
Visualization and manipulation of four-leaf clover-shaped electronic state in cuprate
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Zechao Wang, Fengyu Yao, Yuchen Huo, Zhongxu Wei, Zhiyuan Song, Mingqiang Ren, Ziyuan Cheng, Jinfeng Jia, Yu-Jie Sun, Qi-Kun Xue
High-Tc superconductivity in cuprates arises from carrier doping of an antiferromagnetic Mott insulator. Associated with these changes are spectral-weight transfers from the high-energy to low-energy, giving rise to a variety of intriguing electronic phenomena. In this study, for the first time, we discovered a 2a0 sized four-leaf clover-shaped (FLC) electronic state at low-energy, accompanied with the emergence of a characteristic “kink” around 16meV. With increasing doping, the number of FLC pattern decreases and ultimately vanishes in the overdoped region. Remarkably, we achieved real-time electric-field manipulation of this FLC state, through innovative in-situ scanning tunneling microscopy probe. This novel FLC state may not only redefine our understanding of precursor states of pairing, but also reveals its crucial role as a tunable electronic phase in high-Tc superconductors.
Superconductivity (cond-mat.supr-con)
12 pages, 4 figres,
Analytical Calculation of Viscosity in Rouse Networks Below Gelation Transition
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-06-27 20:00 EDT
This work establishes an exact relationship between the zero-shear viscosity and the radius of gyration for generalized Rouse model with arbitrary network configurations. Building on this fundamental relationship, we develop a random graph approach to derive analytical expressions for network viscosity in mean-field connected systems through coarse-grained graph viscosity relations. The theory fully characterizes the subcritical regime, determining precise asymptotic behavior in both dilute and pre-gelation limits.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
Ultrafast photocurrent detection reveals that device efficiency is dominated by ultrafast exciton dissociation not exciton diffusion
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Zachary M. Faitz, Chris J. Blackwell, Dasol Im, Abitha Dhavamani, Michael Arnold, Martin T. Zanni
Excitons diffusing to a charge-separating interface is a necessary step to convert energy into current in next-generation photovoltaics. In this report, made possible by a new ultrafast spectrometer design, we compare exciton dynamics measured using both photoabsorption- and photocurrent-detected transient and 2D spectroscopies. For a device with semiconducting carbon nanotubes as the exciton transport material, we find that photoabsorption detection greatly overestimates the importance of long-lived excitons for device performance. Excitons diffuse and transfer between nanotubes for several picoseconds, but the large majority of photocurrent is created within 30fs by excitons that diffuse little to the C60 electron transfer material. These results change our understanding of the material features most important for these photovoltaics. Photoabsorption detection measures all excitons, but not all photogenerated excitons generate current. To understand device efficiency, this study points to the necessity for directly measuring the exciton dynamics responsible for photocurrent.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Observation of Cavity-Mediated Nonlinear Landau Fan and Modified Landau Level Degeneracy in Graphene Quantum Transport
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Hongxia Xue, Hsun-Chi Chan, Zuzhang Lin, Dalin Boriçi, Shaobo Zhou, Yanan Wang, Kenji Watanabe, Takashi Taniguchi, Cristiano Ciuti, Wang Yao, Dong-Keun Ki, Shuang Zhang
Recent studies on cavity-coupled two-dimensional electron gas demonstrate that vacuum-field engineering can tailor electronic transport properties of materials. By achieving ultra-strong coupling between a terahertz resonator and mesoscopic graphene, we demonstrate that cavity vacuum fields can alter the effective degeneracies of Landau levels, resulting in a nonlinear Landau fan diagram for massless Dirac fermions while preserving quantum-Hall quantization. Specifically, by leveraging graphene’s gate-tunability, we observe that quantum-Hall features, minimum longitudinal and quantized Hall conductance for a given filling factor, occur at carrier densities reduced by more than 20 percent compared to systems without cavity. Theoretical analysis attributes this effect to the virtual cavity photon mediated transitions between the non-equidistant Landau levels in graphene, significantly reducing their effective degeneracy. This study paves the way for investigating cavity quantum electrodynamics in highly tunable, atomically thin two-dimensional crystals.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 4 figures
Nonideal Statistical Field Theory at NLO
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-27 20:00 EDT
In this work we introduce a field theory capable of describing the critical properties of nonideal systems undergoing continuous phase transitions beyond the leading order radiative corrections or in the number of loops (effective field theories limited only to leading order were recently defined in literature). These systems present defects, inhomogeneities and impurities as opposed to ideal ones which are perfect, homogeneous and pure. We compute the values of the critical exponents of the theory beyond leading order and compare with their corresponding experimental measured results. The results show some interplay between nonideal effects and fluctuations.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph)
8 pages, 4 figures, 2 tables
Imaginary Time Formalism for Causal Nonlinear Response Functions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
It is well established that causal linear response functions can be found by computing the much simpler imaginary time-ordered Matsubara functions and performing an analytic continuation. This principle is the basis for much of our understanding of linear response for interacting and disordered systems, via diagrammatic perturbation theory. Similar imaginary-time approaches have recently been introduced for computing nonlinear response functions as well, although the rigorous connection between Matsubara and causal nonlinear response functions has not been clearly elucidated. In this work, we provide a proof of this connection to all orders in perturbation theory. Using an equations of motion approach, we show by induction that casual nonlinear response functions at every order can be obtained from an analytic continuation of an appropriate time-ordered Matsubara function. We demonstrate this connection explicitly for second order response functions in the Lehmann representation. As a byproduct of our approach, we derive an explicit expression for the Lehmann representation of $ n$ -th order response functions by solving the equations of motion. We also use our result to find an analytic spectral density representation for both causal response functions and Matsubara functions. Finally, we show how our results lead to a family of generalized sum rules, focusing explicitly on the asymptotic expression for $ n$ -th harmonic generation rate.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
7+15pgs
Spin-orbit interaction, band topology, and spin texture in BiInO3(001) surface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Ramsamoj Kewat, Nirmal Ganguli
This research investigates the implication of spin-orbit interaction (SOI) and symmetry on the band topology and spin texture at the (001) surface of BiInO$ _3$ . Using density functional theory (DFT) and symmetry analysis, the study explores the impact of surface termination on the electronic structure, particularly focusing on how the loss of translational symmetry at the surface influences the band topology of the surface states. Key findings include discovering two dangling surface states (named SS1 and SS2) with distinct spin textures. SS1 exhibits Rashba spin splitting due to surface inversion asymmetry, characterised by isotropic effective mass and tangential spin alignment on constant energy contours. In contrast, SS2 features a persistent spin Texture (PST) spin texture, a momentum-independent spin polarisation. The orbital contributions to these bands, dominated by specific s and p orbitals, dictate the direction and nature of the spin texture. This study highlights BIO’s potential as a platform for spintronic applications, where control over spin textures and electronic properties at the surface can enable the design of advanced spin-based devices. The findings bridge the gap between symmetry-driven theoretical frameworks and practical material functionalities, offering insights into the interplay of surface symmetry, SOI, and band topology.
Materials Science (cond-mat.mtrl-sci)
Photocurrents induced by k-linear terms in semiconductors and semimetals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
We develop a six-band $ \mathbf{k} \cdot \mathbf{p}$ model to describe the electronic structure and optical response of chiral multifold semimetals, such as RhSi. By means of invariants method we construct the effective Hamiltonian describing the states near the $ \Gamma$ -point of the Brillouin zone where the spin-orbit coupling and $ \mathbf{k}$ -linear Rashba terms, which are crucial for circular photogalvanic effect, are taken into account. The model is parameterized using tight-binding calculations. We compute the interband absorption spectrum, showing a linear-in-frequency dependence at low energies and a resonant feature near the spin-orbit splitting energy. Furthermore, we calculate the circular photogalvanic effect. In agreement with previous works the current generation rate at low frequencies exhibits a quantized low-frequency response, governed by the universal value $ |\mathcal{C}| = 4$ for the effective topological charge. Our results provide an analytical framework for understanding the role of Rashba coupling and topology in the optoelectronic properties of multifold chiral semimetals.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
5+ pages, 2 figures, and 6+ pages supplement
Anisotropy-Induced Magnetic Field Generation in Bidimensional Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Diogo Simões, Hugo Terças, Jorge Ferreira
We investigate an electromagnetic instability in two-dimensional materials arising from an anisotropy of the Fermi surface, utilizing a kinetic model accounting for the effects of the values of temperature, chemical potential and anisotropy ratio, as well as considering both linear and quadratic low-energy band structures. The wavenumber-dependent growth-rate of these modes is derived in the linear regime, and their confinement, contrasting with stable electromagnetic waves in these systems, is described. The generation of structured out-of-plane magnetic fields, as well as their behaviour in saturation, is shown using fully kinetic and non-linear simulations.
Materials Science (cond-mat.mtrl-sci), Plasma Physics (physics.plasm-ph)
Distinct element-specific nanoscale magnetization dynamics following ultrafast laser excitation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Emma Bernard, Rahul Jangid, Nanna Zhou Hagström, Meera Madhavi, Jeffrey A. Brock, Matteo Pancaldi, Dario De Angelis, Flavio Capotondi, Emanuele Pedersoli, Kyle Rockwell, Mark W. Keller, Stefano Bonetti, Eric E. Fullerton, Ezio Iacocca, Thomas J. Silva, Roopali Kukreja
Time-resolved ultrafast extreme ultraviolet (EUV) magnetic scattering is used to study laser-driven ultrafast magnetization dynamics of labyrinthine domains in a [Co/Ni/Pt] multilayer. Our measurements at the Co and Ni M-edges reveal distinct ultrafast distortions of the scattering pattern position and width for Ni compared to Co. Ni shows a strong modification of the scattering pattern, 9 to 41 times stronger than Co. As distortions of the labyrinthine pattern in reciprocal space relate to the modification of domain textures in real space, significant differences in Co and Ni highlight a 3D distortion of the domain pattern in the far-from-equilibrium regime.
Materials Science (cond-mat.mtrl-sci)
Synergy of Rashba and Topological Effects for High-Performance Bismuth-Based Thermoelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-06-27 20:00 EDT
Lei Peng, Ruixiao Lian, Hongyu Chen, Ben Li, Yu Wu, Yuxiang Zheng, Hao Zhang
Band convergence is a key strategy for enhancing thermoelectric (TE) performance. Herein, we demonstrate a promising approach to enhance band convergence through inducing Rashba splitting in topological insulators. Theoretically designed Janus $ \beta$ -Bi$ _2$ Se$ _2$ Te and $ \beta$ -Bi$ _2$ Te$ _2$ Se exhibited inherent topological band inversion and Rashba splitting due to the strong spin-orbit coupling (SOC) with broken inversion symmetry. These characteristics synergistically improve band convergence, leading to a substantially enhanced power factor. Meanwhile, the Janus structural asymmetry suppresses lattice thermal conductivity. Consequently, Janus structures achieve boosted TE performance, especially for $ \beta$ -Bi$ _2$ Se$ _2$ Te, peaking figure of merit ($ zT$ ) of 2.82. This work establishes a new framework for designing Janus topological compounds with high TE performance by the synergistic effect of Rashba splitting and band inversion.
Materials Science (cond-mat.mtrl-sci)
Optimal superconductivity near a Lifshitz transition in strained (La,Pr)$_3$Ni$_2$O$_7$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Siheon Ryee, Niklas Witt, Giorgio Sangiovanni, Tim O. Wehling
High-temperature superconductivity in pressurized and strained bilayer nickelates (La,Pr)$ _3$ Ni$ 2$ O$ 7$ has emerged as a new frontier. One of the key unresolved issues concerns the fermiology that underlies superconductivity. On both theoretical and experimental sides, no general consensus has been reached, and conflicting results exist regarding whether the relevant Fermi surface involves a hole $ \gamma$ pocket, or not. Here, we address this issue by unveiling a Janus-faced role of the $ \gamma$ pocket in spin-fluctuation-mediated superconductivity. We show that this pocket simultaneously induces dominant pair-breaking and pair-forming fluctuations for the leading $ s\pm$ -wave pairing. Consequently, an optimal superconducting transition temperature $ T\mathrm{c}$ is achieved when the $ \gamma$ pocket surfaces at the Fermi level, placing the system near a Lifshitz transition. This suggests that superconductivity can emerge provided the maximum energy level of the $ \gamma$ pocket lies sufficiently close to the Fermi level, either from below or above. Our finding not only reconciles two opposing viewpoints on the fermiology, but also naturally explains recent experiments on (La,Pr)$ _3$ Ni$ _2$ O$ 7$ thin films, including the superconductivity under compressive strain, two conflicting measurements on the Fermi surface, and the dome shape of $ T\mathrm{c}$ as a function of hole doping.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Frustrated edge currents in bilayers formed of s- and d-wave superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-06-27 20:00 EDT
Vedangi Pathak, Oguzhan Can, Nirek Brahmbhatt, Marcel Franz
We explore edge currents in heterostructures formed of a high-$ T_c$ cuprate and a conventional $ s$ -wave superconductors. The resulting $ d\pm is$ superconductor spontaneously breaks time reversal symmetry and, remarkably, exhibits large edge currents along certain edge directions in spite of being topologically trivial. In addition we find that the edge currents are frustrated such that they appear to emerge from or flow into sample corners, seemingly violating charge conservation. Careful self-consistent solutions that guarantee charge conservation are required to understand how this frustration is resolved in physical systems. Calculations within the Ginzburg-Landau theory framework and fully self-consistent microscopic lattice models reveal intriguing patterns of current reversals depending on edge orientation, accompanied by spontaneous formation of magnetic flux patterns which can be used to detect these phenomena experimentally. Our study illuminates the interplay between time-reversal symmetry breaking and unconventional superconductivity in high-$ T_c$ superconducting heterostructures, and shows that sizable edge currents are possible even in the absence of non-trivial bulk topology.
Superconductivity (cond-mat.supr-con)
13+2 pages, 7 figures. Comments welcome!
New plasmon-like mode in PdTe$_{2}$: Raman scattering and memory function study
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-06-27 20:00 EDT
Bharathiganesh Devanarayanan, Sahil Rathi, Jalaja Pandya, Sonika, C.S.Yadav, Navinder Singh, Satyendra Nath Gupta
PdTe$ _2$ is a type II Dirac semimetal that has garnered significant attention due to its intriguing electronic and topological properties. Here, we report temperature dependent Raman scattering study of PdTe$ _2$ in the temperature range from 10 K to 300 K. Our study reveals emergence of a new unreported peak below 100 K, centered around 250 cm$ ^{-1}$ . We argue that the new mode is not a phonon mode because the Raman spectra calculated using Density Functional Theory shows only two intense peaks at 85 $ cm^{-1}$ and 128 $ cm^{-1}$ . To ascertain the origin of this new peak, we constructed a microscopic model of electrons coupling to a single plasmon mode at 250 $ cm^{-1}$ and using the memory function formalism, we obtained that the Raman relaxation rate is linear in frequency. We also performed phenomenological analysis of the Raman response from the experimental data and computed frequency dependent Raman relaxation rate, which is also found to exhibit a linear dependence on frequency. With the congruence of our theoretical and phenomenological results we could ascertain that the new mode observed at low temperatures is indeed a plasmon-like mode. Further, phonon frequencies and line widths of the two phonon modes exhibit anomalous behavior above 100 K.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
15 pages, 7 figures
Revealing electron-lattice decoupling by Peltier thermometry and nanoscale thermal imaging in graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Saurabh Kumar Srivastav, Tobias Völkl, Gary Quaresima, Yuri Myasoedov, Martin E. Huber, Kenji Watanabe, Takashi Taniguchi, L. S. Levitov, D. A. Pesin, Eli Zeldov
Electrical currents in low-dimensional quantum materials can drive electrons far from equilibrium, creating stark imbalance between electron and lattice temperatures. Yet, no existing methods enable simultaneous nanoscale mapping of both temperatures at cryogenic conditions. Here, we introduce a scanning probe technique that images the local lattice temperature and extracts electron temperature at gate-defined p-n junctions in graphene. By applying an alternating electrical current and analyzing first- and second-harmonic responses, we disentangle Joule heating from the Peltier effect-the latter encoding the local electron temperature. This enables the first spatially resolved cryogenic imaging of both phenomena in graphene. Even under modest current bias, the electron temperature increases by nearly three orders of magnitude more than the lattice temperature, revealing strong electron-phonon decoupling and indicating a previously unrecognized electron cooling pathway. Our minimally invasive method is broadly applicable to van der Waals heterostructures and opens new avenues for probing energy dissipation and non-equilibrium transport in correlated and hydrodynamic electron systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
31 pages, 4 main figures, 8 extended data figures
Landau levels of a Dirac electron in graphene from non-uniform magnetic fields
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
The occurrence of Landau levels in quantum mechanics is well known when a charged particle is subjected to a uniform magnetic field. Considering the recent interest in the electronic properties of graphene which admits a dispersion relation which is linear in the momentum near the Dirac points, we revisit the problem of Landau levels in the spirit of the Dirac Hamiltonian and ask if there are certain non-uniform magnetic fields which also lead to a spectrum consisting of the Landau levels. The answer, as we show, is in the affirmative. In particular, by considering isospectral deformations of the uniform magnetic field, we present explicit expressions for non-uniform magnetic fields that are strictly isospectral to their uniform counterpart, thus supporting the Landau levels.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Exactly Solvable and Integrable Systems (nlin.SI), Quantum Physics (quant-ph)
Rashba spin-orbit coupling and artificially engineered topological superconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-06-27 20:00 EDT
Sankar Das Sarma, Katharina Laubscher, Haining Pan, Jay D. Sau, Tudor D. Stanescu
One of the most important physical effects in condensed matter physics is the Rashba spin-orbit coupling (RSOC), introduced in seminal works by Emmanuel Rashba. In this article, we discuss, describe, and review (providing critical perspectives on) the crucial role of RSOC in the currently active research area of topological quantum computation. Most, if not all, of the current experimental topological quantum computing platforms use the idea of Majorana zero modes as the qubit ingredient because of their non-Abelian anyonic property of having an intrinsic quantum degeneracy, which enables nonlocal encoding protected by a topological energy gap. It turns out that RSOC is a crucial ingredient in producing a low-dimensional topological superconductor in the laboratory, and such topological superconductors naturally have isolated localized midgap Majorana zero modes. In addition, increasing the RSOC strength enhances the topological gap, thus enhancing the topological immunity of the qubits to decoherence. Thus, Rashba’s classic work on SOC may lead not only to the realization of localized non-Abelian anyons, but also fault tolerant quantum computation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Continuous symmetry breaking in 1D spin chains and 1+1D field theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-06-27 20:00 EDT
We argue that ground states of 1D spin chains can spontaneously break U(1) ``easy-plane’’ spin rotation symmetry, via true long-range order of $ (S^x, S^y)$ , at the phase transition between two quasi-long-range-ordered phases. The critical point can be reached by tuning a single parameter in a Hamiltonian with the same symmetry as the XXZ model, without further fine-tuning. Equivalently, it can arise in systems of bosons with particle-hole symmetry, as a long-range-ordered transition point between two quasi-long-range-ordered superfluids. Our approach is to start with the continuum field theory of the isotropic Heisenberg ferromagnet and consider generic perturbations that respect easy-plane symmetry. We argue for a renormalization-group flow to a critical point where long-range order in $ (S^x, S^y)$ is enabled by coexisting critical fluctuations of $ S^z$ . (We also discuss multicritical points where further parameters are tuned to zero.) These results show that it is much easier to break continuous symmetries in 1D than standard lore would suggest. The failure of standard intuition for 1D chains (based on the quantum–classical correspondence) can be attributed to Berry phases, which prevent the 1+1D system from mapping to a classical 2D spin model. The present theory also gives an example of an ordered state whose Goldstone mode is interacting even in the infra-red, rather than becoming a free field.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
6 pages + appendices