CMP Journal 2025-05-06
Statistics
Nature: 3
Nature Materials: 2
Nature Physics: 1
Physical Review Letters: 8
Physical Review X: 2
arXiv: 102
Nature
A kinase mediator of rhizobial symbiosis and immunity in Medicago
Original Paper | Plant immunity | 2025-05-05 20:00 EDT
Dapeng Wang, Rui Jin, Xiaobao Shi, Haoran Guo, Xinhang Tan, Achen Zhao, Xinghua Lian, Huiling Dai, Shaozhuang Li, Kexu Xin, Changfu Tian, Jun Yang, Wansheng Chen, Alberto P. Macho, Ertao Wang
Legume roots secure nitrogen by forming a symbiosis with soil rhizobia but remain resistant to pathogenic bacteria1-4. How this tolerance to rhizobia is achieved without compromising plant immunity is largely unknown. Here, we identify the cytoplasmic kinase MtLICK1/2, which interacts with nodulation factor receptor MtLYK3 to drive symbiotic signaling and suppress plant immunity. Rhizobial infection and nodule development are defective in Mtlick1/2, phenocopying the Mtlyk3-1 mutant. MtLICK1/2 and MtLYK3 undergo reciprocal trans-phosphorylation during rhizobial symbiosis. Phosphorylated MtLYK3 activates the receptor-like kinase MtDMI2 to stimulate symbiotic signaling. MtLICK1/2 is activated in the rhizobia infection area to suppress plant immunity. Thus, MtLICK1/2 and MtLYK3 together amplify symbiotic signaling and dampen host immunity to enable legume-rhizobium symbiosis.
Plant immunity, Plant signalling, Rhizobial symbiosis
Molecular basis of SIFI activity in the integrated stress response
Original Paper | Cryoelectron microscopy | 2025-05-05 20:00 EDT
Zhi Yang, Diane L. Haakonsen, Michael Heider, Samuel R. Witus, Alex Zelter, Tobias Beschauner, Michael J. MacCoss, Michael Rapé
Chronic stress response activation impairs cell survival and causes devastating degenerative di-seases 1-3. Organisms accordingly deploy silencing factors, such as the E3 ubiquitin ligase SIFI, to terminate stress response signaling and ensure cellular homeostasis 4. How a silencing factor can sense stress across cellular scales to elicit timely stress response inactivation is poorly understood. Here, we combine cryo-electron microscopy of endogenous SIFI with AlphaFold modeling and biochemical analyses to report the structural and mechanistic basis of integrated stress response silencing. SIFI detects both stress-indicators and stress response components through flexible domains within an easily accessible scaffold, before building linkage-specific ubiquitin chains at separate, sterically restricted elongation modules. Ubiquitin handover by a ubiquitin-like domain couples versatile substrate modification to linkage-specific ubiquitin polymer formation. Stress response silencing therefore exploits a catalytic mechanism that is geared towards processing many diverse proteins and hence allows a single enzyme to monitor and, if needed, modulate a complex cellular state.
Cryoelectron microscopy, Protein quality control, Ubiquitin ligases
Naturally ornate RNA-only complexes revealed by cryo-EM
Original Paper | Computational biophysics | 2025-05-05 20:00 EDT
Rachael C. Kretsch, Yuan Wu, Svetlana A. Shabalina, Hyunbin Lee, Grace Nye, Eugene V. Koonin, Alex Gao, Wah Chiu, Rhiju Das
Myriad families of natural RNAs have been proposed, but not yet experimentally shown, to form biologically important structures1-4. Here we report three-dimensional structures of three large ornate bacterial RNAs using cryogenic electron microscopy at resolutions of 2.9-3.1 Å. Without precedent among previously characterized natural RNA molecules, Giant, Ornate, Lake- and Lactobacillales-Derived (GOLLD), Rumen-Originating, Ornate, Large (ROOL), and Ornate Large Extremophilic (OLE) RNAs form homo-oligomeric complexes whose stoichiometries are retained at concentrations lower than expected in the cell. OLE RNA forms a dimeric complex with long co-axial pipes spanning two monomers. Both GOLLD and ROOL form distinct RNA-only multimeric nanocages with diameters larger than the ribosome, empty except for a disordered loop. Extensive intra- and intermolecular A-minor interactions, kissing loops, an unusual A-A helix, and other interactions stabilize the three complexes. Sequence covariation analysis of these large RNAs reveals evolutionary conservation of intermolecular interactions, supporting the biological importance of large, ornate RNA quaternary structures that can assemble without any involvement of proteins.
Computational biophysics, Cryoelectron microscopy, Molecular biophysics
Nature Materials
Ultrasound-activated piezoelectric nanostickers for neural stem cell therapy of traumatic brain injury
Original Paper | Nanoparticles | 2025-05-05 20:00 EDT
Wenhan Wang, Keyi Li, Wenjun Ma, Yiwei Li, Feng Liu, Ying Kong, Liang Wang, Fan Yi, Yuanhua Sang, Gang Li, Hong Liu, Jichuan Qiu
Traumatic brain injury (TBI) is associated with life-threatening and permanent disabilities. Given the limited capacity of neurons to regenerate, effective treatments for TBI are lacking. Neural stem cells (NSCs) can differentiate into fully functioning neurons and thus hold promise for TBI treatment. Nonetheless, NSC differentiation and proliferation are slow and inefficient. Studies have shown that piezoelectric stimulation is capable of promoting the differentiation and proliferation of NSCs. Here, we describe barium titanate-reduced graphene oxide (BTO/rGO) hybrid piezoelectric nanostickers that promote NSC proliferation and differentiation. These hybrid nanostickers attach to NSC membranes, serving as long-term generators of piezoelectric potentials upon ultrasound stimulation. BTO/rGO nanostickers promote rapid neuronal differentiation and maturation by activating the voltage-gated calcium channel/Ca2+/calmodulin-dependent protein kinase II/cAMP response element-binding protein pathways. Transplantation of NSCs with BTO/rGO nanostickers into the injured brain region of rats with TBI substantially repairs brain tissue and effectively restores physiological functions after 28 d following 5-min ultrasound irradiation every 2 d. These results demonstrate the potential of the combination of NSCs and BTO/rGO nanostickers for TBI treatment.
Nanoparticles, Neural stem cells
Moiré periodic and quasiperiodic crystals in heterostructures of twisted bilayer graphene on hexagonal boron nitride
Original Paper | Materials science | 2025-05-05 20:00 EDT
Xinyuan Lai, Guohong Li, Angela M. Coe, Jedediah H. Pixley, Kenji Watanabe, Takashi Taniguchi, Eva Y. Andrei
Stacking two atomic crystals with a twist between their crystal axes produces moiré potentials that modify the electronic properties. Here we show that double-moiré potentials generated by superposing three atomic crystals create a unique class of tunable quasiperiodic structures that alter the symmetry and spatial distribution of the electronic wavefunctions. By using scanning tunnelling microscopy and scanning tunnelling spectroscopy to study twisted bilayer graphene on hexagonal boron nitride, we unveil a moiré phase diagram defined by the lattice constants of the two moiré lattices (graphene-on-graphene and graphene-on-hexagonal boron nitride), comprising both commensurate periodic and incommensurate quasiperiodic crystals. Remarkably, the 1:1 commensurate crystals, which should theoretically exist at only one point on this phase diagram, are observed over a wide range, demonstrating an unexpected self-alignment mechanism. The incommensurate crystals include quasicrystals, which are quasiperiodic and feature a Bravais-forbidden dodecagonal symmetry, and intercrystals, which are also quasiperiodic but lack forbidden symmetries. This rich variety of tunable double-moiré structures offers a synthetic platform for exploring the unique electronic properties of quasiperiodic crystals, which are rarely found in nature.
Materials science, Mathematics and computing
Nature Physics
Proof-of-principle demonstration of muon production with an ultrashort high-intensity laser
Original Paper | Experimental particle physics | 2025-05-05 20:00 EDT
Feng Zhang, Li Deng, Yanjie Ge, Jiaxing Wen, Bo Cui, Ke Feng, Hao Wang, Chen Wu, Ziwen Pan, Hongjie Liu, Zhigang Deng, Zongxin Zhang, Liangwen Chen, Duo Yan, Lianqiang Shan, Zongqiang Yuan, Chao Tian, Jiayi Qian, Jiacheng Zhu, Yi Xu, Yuhong Yu, Xueheng Zhang, Lei Yang, Weimin Zhou, Yuqiu Gu, Wentao Wang, Yuxin Leng, Zhiyu Sun, Ruxin Li
Muons play a crucial role in both fundamental and applied physics. Traditionally, they have been generated from cosmic rays or with proton accelerators. With the advent of ultrashort high-intensity lasers capable of accelerating electrons to gigaelectronvolt energies, muons can also be produced in laser laboratories. Here we report a proof-of-principle experiment of muon production. We accelerated an electron beam to gigaelectronvolt energies with an ultrashort, high-intensity laser pulse and passed the beam through a lead converter target in which muons were generated. We confirmed the muon signal by measuring its lifetime. We investigated the photo-production, electro-production and Bethe-Heitler processes underlying muon generation and their subsequent detection with Geant4 simulations. The results show that the dominant contribution stems from photo-production and electro-production. We estimate that a muon yield of up to 0.01 muon per incoming electron could be achieved in the converter target. This laser-driven muon source features compact, ultrashort pulses and high flux. Moreover, its implementation in a small laser laboratory is relatively straightforward, which dramatically reduces barriers for research in areas such as muonic X-ray elemental analysis or muon spin spectroscopy.
Experimental particle physics, Plasma-based accelerators
Physical Review Letters
Energy Barrier of Hypergraph Product Codes
Research article | Quantum error correction | 2025-05-05 06:00 EDT
Guangqi Zhao, Andrew C. Doherty, and Isaac H. Kim
A macroscopic energy barrier is a necessary condition for self-correcting quantum memory. In this Letter, we prove tight bounds on the energy barrier applicable to any quantum code obtained from the hypergraph product of two classical codes. If the underlying classical codes are low-density parity-check codes (LDPC), the energy barrier of the quantum code is shown to be the minimum energy barrier of the underlying classical codes (and their transposes) up to an additive $O(1)$ constant.
Phys. Rev. Lett. 134, 180601 (2025)
Quantum error correction, Quantum memories
Genuine Quantum Non-Gaussianity and Metrological Sensitivity of Fock States Prepared in a Mechanical Resonator
Research article | Hybrid quantum systems | 2025-05-05 06:00 EDT
Q. Rumman Rahman, Igor Kladarić, Max-Emanuel Kern, Lukáš Lachman, Yiwen Chu, Radim Filip, and Matteo Fadel
Fock states of the quantum harmonic oscillator are fundamental to quantum sensing and information processing, serving as key resources for exploiting bosonic degrees of freedom. Here, we prepare high Fock states in a high-overtone bulk acoustic wave resonator by coupling it to a superconducting qubit and applying microwave pulses designed using quantum optimal control. We characterize the experimentally realized states by employing a criterion for genuine quantum non-Gaussianity (QNG) designed to reveal multiphonon contributions. Although energy relaxation and decoherence limit the achievable fidelities, we demonstrate genuine QNG features compatible with a Fock state $|6\rangle$, confirming that the prepared states cannot be generated through Gaussian operations on states with up to Fock state $|5\rangle$ contributions. We further investigate the robustness of these QNG features to losses and their utility in sensing displacement amplitudes. In particular, we introduce a hierarchy based on the quantum Fisher information and show that, despite decoherence and measurement imperfections, the prepared states achieve a displacement sensitivity surpassing that of an ideal Fock state $|3\rangle$. Our results have immediate applications in quantum sensing and simulations with high-overtone bulk acoustic wave resonator devices.
Phys. Rev. Lett. 134, 180801 (2025)
Hybrid quantum systems, Non-gaussian quantum states, Optomechanics, Quantum control, Quantum metrology, Quantum sensing
Observation of the Charmonium Decay ${\eta }{c}\rightarrow \gamma \gamma $ in $J/\psi \rightarrow \gamma {\eta }{c}$
Research article | Branching fraction | 2025-05-05 06:00 EDT
M. Ablikim et al. (BESIII Collaboration)
Using $(2712.4\pm{}14.3)\times{}{10}^{6}\text{ }\text{ }\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, the decay ${\eta }{c}\rightarrow \gamma \gamma $ in $J/\psi \rightarrow \gamma {\eta }{c}$ is observed. We determine the product branching fraction $\mathcal{B}(J/\psi \rightarrow \gamma {\eta }{c})\times{}\mathcal{B}({\eta }{c}\rightarrow \gamma \gamma )=(5.23\pm{}0.2{6}{\mathrm{stat}}\pm{}0.3{0}{\mathrm{syst}})\times{}{10}^{- 6}$. This result is consistent with the lattice QCD calculation $(5.34\pm{}0.16)\times{}{10}^{- 6}$ from HPQCD in 2023. By using the world-average values of $\mathcal{B}(J/\psi \rightarrow \gamma {\eta }{c})$ and the total decay width of ${\eta }{c}$, the partial decay width $\mathrm{\Gamma }({\eta }{c}\rightarrow \gamma \gamma )$ is determined to be $(11.30\pm{}0.5{6}{\mathrm{stat}}\pm{}0.6{6}{\mathrm{syst}}\pm{}1.1{4}{\mathrm{ref}})\text{ }\text{ }\mathrm{keV}$, which deviates from the corresponding world-average value by $3.4\sigma $.
Phys. Rev. Lett. 134, 181901 (2025)
Branching fraction, Particle decays, Quantum chromodynamics, Charm quark, Quarkonia
In Situ Imaging of the Thermal de Broglie Wavelength in an Ultracold Bose Gas
Research article | Bose gases | 2025-05-05 06:00 EDT
Jinggang Xiang, Enid Cruz-Colón, Candice C. Chua, William R. Milner, Julius de Hond, Jacob F. Fricke, and Wolfgang Ketterle
An innovative way to image atoms in cold gases could provide deeper insights into the atoms’ quantum correlations.
Phys. Rev. Lett. 134, 183401 (2025)
Bose gases, Cold atoms & matter waves, Ultracold gases
Measuring Pair Correlations in Bose and Fermi Gases via Atom-Resolved Microscopy
Research article | BCS-BEC crossover | 2025-05-05 06:00 EDT
Ruixiao Yao, Sungjae Chi, Mingxuan Wang, Richard J. Fletcher, and Martin Zwierlein
An innovative way to image atoms in cold gases could provide deeper insights into the atoms’ quantum correlations.
Phys. Rev. Lett. 134, 183402 (2025)
BCS-BEC crossover, Bose gases, Bose-Einstein condensates, Fermi gases, Fluctuation-dissipation theorem, Superfluidity, Ultracold collisions, 2-dimensional systems, Atomic gases, Ultracold gases, Correlation function measurements
Quantum Gas Microscopy of Fermions in the Continuum
Research article | Fermi gases | 2025-05-05 06:00 EDT
Tim de Jongh, Joris Verstraten, Maxime Dixmerias, Cyprien Daix, Bruno Peaudecerf, and Tarik Yefsah
An innovative way to image atoms in cold gases could provide deeper insights into the atoms’ quantum correlations.
Phys. Rev. Lett. 134, 183403 (2025)
Fermi gases, Quantum correlations, foundations & formalism, Quantum many-body systems, Ultracold gases, Correlation function measurements
Universal Photon Blockade
Research article | Quantum optics | 2025-05-05 06:00 EDT
Yan-Hui Zhou, Tong Liu, Qi-Ping Su, Xing-Yuan Zhang, Qi-Cheng Wu, Dong-Xu Chen, Zhi-Cheng Shi, H. Z. Shen, and Chui-Ping Yang
Photon blockades are traditionally classified into conventional and unconventional types, depending on distinct physical mechanisms. Regarding the cavity decay rate $\kappa $, the conventional photon blockade takes place under strong nonlinearity condition ($g>\kappa $), whereas the unconventional photon blockade occurs in the regime of weak nonlinearity ($g<\kappa $). We here propose how to derive an optimal condition for photon blockade utilizing a two-photon Jaynes-Cummings model. Under this condition, the equal-time second-order correlation function reaches its minimum, leading to photon antibunching in both conventional and unconventional photon blockade regimes ($g>\kappa $ and $g<\kappa $), even in $g\sim \kappa $. This characteristic is termed universal photon blockade. By comparing it with the conventional and the unconventional photon blockades in the weak-driving limit, the advantages of universal photon blockade are revealed. Our proposal paves an avenue towards the future study of photon blockades and has potential applications in generating antibunched photons.
Phys. Rev. Lett. 134, 183601 (2025)
Quantum optics, Single- and few-photon ionization & excitation
Controlling Molecular Dynamics by Exciting Atoms in a Cavity
Research article | Atomic & molecular processes in external fields | 2025-05-05 06:00 EDT
András Csehi, Krisztián Szabó, Ágnes Vibók, Lorenz S. Cederbaum, and Gábor J. Halász
Placing an atom and a molecule in a cavity opens the door to initialize molecular dynamics by exciting a level of the atom. This approach enlarges the range of choosing the light source to trigger molecular dynamics substantially. The interplay of the atomic, molecular, and photonic populations gives rise to rich dynamics. The cavity photon plays the role of a mediator between the atom and the molecule and it is found that the photonic population is rather low throughout and its evolution follows that of the molecule. Cavities are known to be subject to losses. In spite of the losses it is demonstrated that the presence of the atom gives rise to a long-lived dynamics that should be of relevance for experimental investigations. The presence of more atoms and molecules is expected to further enrich the dynamics.
Phys. Rev. Lett. 134, 188001 (2025)
Atomic & molecular processes in external fields, Light-matter interaction, Plasmonics, Strong electromagnetic field effects, Cavity methods
Physical Review X
Coherent Phonons and Quasiparticle Renormalization in Semimetals from First Principles
Research article | Electron-phonon coupling | 2025-05-05 06:00 EDT
Christoph Emeis, Stephan Jauernik, Sunil Dahiya, Yiming Pan, Carl E. Jensen, Petra Hein, Michael Bauer, and Fabio Caruso
A new theory linking light-induced atomic vibrations to ultrafast changes in electronic behavior offers a path to engineer the properties of semimetals using light.
Phys. Rev. X 15, 021039 (2025)
Electron-phonon coupling, First-principles calculations, Quasiparticles & collective excitations, Semimetals, Angle-resolved photoemission spectroscopy, Ultrafast pump-probe spectroscopy
Realistic Ab Initio Predictions of Excimer Behavior under Collective Light-Matter Strong Coupling
Research article | Electronic structure of atoms & molecules | 2025-05-05 06:00 EDT
Matteo Castagnola, Marcus T. Lexander, and Henrik Koch
Strong light-matter coupling can reshape chemical dynamics by altering molecular bonding pathways, as shown in a quantum model where polariton formation suppresses excimer bonding beyond a critical interaction threshold.
Phys. Rev. X 15, 021040 (2025)
Electronic structure of atoms & molecules, Light-matter interaction, Photonics, Potential energy surfaces, Quantum optics, Vibrational states
arXiv
Symmetry constrained field theories for chiral spin liquid to spin crystal transitions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Anjishnu Bose, Andrew Hardy, Naren Manjunath, Arun Paramekanti
We consider the spin rotationally invariant Kalmeyer-Laughlin chiral spin liquid (CSL) in systems with broken time-reversal symmetry and explore symmetry constraints on possible conventional spin crystal states accessible via a direct transition. These constraints provide a framework to identify topological invariants of the magnetically ordered state. We show that the existence of a direct transition from a CSL requires a precise compatibility condition between the topological invariants of the ordered state and the anomaly of the CSL. The lattice symmetries also constrain the functional form of the low-energy theory to describe these transitions. This allows us to construct explicit Chern-Simons-matter field theories for the transition into a class of noncoplanar orders identified as candidates directly accessible from the CSL, including the octahedral spin crystal on the kagomé lattice, and the tetrahedral order on the triangular and honeycomb lattice. These transitions can either be described using coupled fractionalized $ \mathbb{CP}^1 $ theories or fractionalized matrix principal chiral models. We also discuss extensions to more general magnetic ordering transitions out of the CSL.
Strongly Correlated Electrons (cond-mat.str-el)
24 pages, 3 figures, 4 tables
Fractionalized fermionic multicriticality in anisotropic Kitaev spin-orbital liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
We study the low-temperature phase diagram of quantum Kitaev-Heisenberg spin-orbital models with XXZ anisotropy on the honeycomb lattice. Within a parton mean-field theory, we identify three different quantum phases, distinguished by their symmetries. Besides a disordered spin-orbital liquid with unbroken U(1) x Z2 spin rotational symmetry, there are two orbital liquid phases characterized by spin long-range order. In these phases, the spin rotational symmetry is spontaneously broken down to residual U(1) and Z2 symmetries, respectively. The symmetric spin-orbital liquid features three flavors of linearly dispersing gapless Majorana fermions. In the symmetry-broken phases, one of the three Majorana excitations remains gapless, while the other two acquire a band gap. The transitions from the symmetric to the symmetry-broken phases are continuous and fall into the fractionalized Gross-Neveu-Z2\ast and Gross-Neveu-SO(2)\ast universality classes, respectively. The transition between the ordered phases is discontinuous. Using a renormalization group analysis based on the epsilon expansion, we demonstrate that the triple point in the phase diagram features fractionalized fermionic multicriticality with emergent SO(3) symmetry.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
11 pages, 4 figures
Observing two-electron interactions with correlation-ARPES
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
A.F. Kemper, F. Goto, H.A. Labib, N. Gauthier, E.H. da Silva Neto, F. Boschini
Identifying and studying the underlying two-electron interactions that give rise to emergent phenomena is a key step in developing a holistic understanding of quantum materials. This step is hindered by the lack of an experiment that can directly interrogate the interactions and the specific quasiparticles involved in the interaction simultaneously. We introduce correlation-ARPES (C-ARPES) as a new experimental method that overcomes this difficulty and directly measures the interactions between specific, chosen quasiparticles by measuring the correlations between two electrons photoemitted from the same pulse (but not the same photon). We illustrate how this technique can extract the underlying interactions, and demonstrate this with an example of phonon-mediated electron-electron interactions, such as those that give rise to charge density waves through the Kohn anomaly mechanism.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Driven Non-Unitary Dynamics of Quantum Critical Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Bastien Lapierre, Pietro Pelliconi, Shinsei Ryu, Julian Sonner
We investigate the interplay between unitary and non-unitary driven many-body dynamics in (1+1)-dimensional quantum critical systems described by conformal field theory (CFT). By formulating a coherent state approach, we demonstrate that the growth of entanglement entropy and energy can be found analytically for a class of non-unitary driven CFTs, where the evolution alternates between real and imaginary time evolution, the latter corresponding to postselected weak measurements. We find that non-unitary evolution leads to the emergence of steady states at infinite times for the cases of periodic, quasiperiodic, and random drives. In a special class of drives, for mixed initial states, we uncover purification phase transitions that arise as a result of the competition between unitary evolution and weak measurements. We compare the CFT evolution with the corresponding non-unitary dynamics of critical lattice models, finding remarkable agreement.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
Spin liquid phase in the Hubbard model: Luttinger-Ward analysis of the slave-rotor formalism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Xia-Ming Zheng, Mehdi Kargarian
We propose an approach for studying the spin liquid phase of the Hubbard model on the triangular lattice by combining the Baym–Kadanoff formalism with the slave rotor parton construction. This method enables the computation of a series of two-body Feynman diagrams for the Luttinger–Ward (LW) functional using a one-loop truncation. This approach enables us to study the U(1) quantum spin liquid phase characterized by a spinon Fermi surface and to derive the Green’s functions for spinons, chargons, and electrons. Our findings extend beyond the standard mean-field approximation by accounting for the effects of gauge field this http URL spatial components of the U(1) gauge field are equivalently represented by interactions that incorporate corrections from the spinon-chargon two-particle random phase approximation. This framework effectively captures the long-range correlations inherent to the U(1) quantum spin liquid and combines non-perturbative quantum field theory with the projective construction, providing new insights into the study of quantum spin liquids and other strongly correlated electron systems. We demonstrate that our approach correctly reprodues the anomalous low-temperature behavior of specific heat – namely, the upturn in $ C_V/T$ as a function of $ T^2$ – in agreement with recent measurments on 1$ T$ - TaS$ _2$ . Moreover, this approach reproduces the resonant peaks in the Mott gap, as observed in cobalt atoms on single-layer 1$ T$ -TaSe$ _{2}$
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 7 figures
Trivalent network model for d3 transition metal dichalcogenides in the 1T structure: Distortions from an effective boundary theory
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Dimer models are well known as prototypes for locally constrained physics. They describe systems where every site on a lattice must be attached to one dimer. Loop models are an extension of this idea, with the constraint that two dimers must touch at each site. Here, we present a further generalization where every site must have three dimers attached – a trivalent network model. As concrete physical realizations, we discuss d$ ^3$ transition metal dichalcogenides in the 1T structure – materials with the structural formula MX$ _2$ (M = Tc, Re) or AM$ ‘$ X$ 2$ (A = Li or Na; M$ ‘$ = Mo, W), where X is a chalcogen atom. These materials have a triangular layer of transition metal atoms, each with three valence electrons in $ t{2g}$ orbitals. Each atom forms valence bonds with three of its nearest neighbours. The geometry of the 1T structure imbues each bond with sharp orbital character. We argue that this enforces a `bending constraint’ where two dimers attached to the same site cannot be parallel. This leads to a highly structured space of configurations, with alternating bonds along each line of the underlying triangular lattice. There is no dynamics, as constraints forbid local rearrangements of dimers. We construct a phase diagram, identifying configurations that minimize potential energy. We find a rhombus-stripe phase in a wide region of parameter space that explains a distortion pattern seen across several materials. Remarkably, this model can be recast as an effective boundary theory, in terms of three Ising chains that are coupled by mutual long-range interactions. As a testable prediction, we propose that a single impurity will generate long-ranged domain walls.
Strongly Correlated Electrons (cond-mat.str-el)
Emergent heavy-fermion physics in a new family of topological insulators RAsS (R = Y, La, and Sm)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Iñigo Robredo, Yuan Fang, Lei Chen, Nazar Zaremba, Yurii Prots, Mitja Krnel, Markus König, Thomas Doert, Jeroen van den Brink, Claudia Felser, Qimiao Si, Eteri Svanidze, Maia G. Vergniory
Realizing topological phases in strongly correlated materials has become a major impetus in condensed matter physics. Although many compounds are now classified as topological insulators, $ f$ -electron systems (with their strong electron correlations) provide an especially fertile platform for emergent heavy-fermion phenomena driven by the interplay of topology and many-body effects. In this study, we examine the crystalline topology of a new RAsS series (R = Y, La, Sm), revealing a structural variant from previous reports. We demonstrate that YAsS and SmAsS host hourglass fermions protected by glide symmetry. SmAsS notably exhibits a strong effective-mass enhancement, placing it alongside SmB$ {}6$ and YbB$ {}{12}$ as a material that couples topological surface states with emergent Kondo physics, yet distinguished by its crystalline symmetry constraints and $ f$ -$ p$ orbital hybridization. To capture these features, we construct a minimal model incorporating $ f$ -electron degrees of freedom, which reproduces the observed topological properties and predicts that the surface states survive in the correlated regime, albeit shifted in energy. Our work thus introduces a new family of correlated topological materials and forecasts the robustness of their surface states under Kondo correlations.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Main text: 11 pages, 5 figures. Supplementary material: 5 pages, 2 figures
Engineering frustrated Rydberg spin models by graphical Floquet modulation
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-06 20:00 EDT
Mingsheng Tian, Rhine Samajdar, Bryce Gadway
Arrays of Rydberg atoms interacting via dipole-dipole interactions offer a powerful platform for probing quantum many-body physics. However, these intrinsic interactions also determine and constrain the models – and parameter regimes thereof – for quantum simulation. Here, we propose a systematic framework to engineer arbitrary desired long-range interactions in Rydberg-atom lattices, enabling the realization of fully tunable $ J_1$ -$ J_2$ -$ J_3$ Heisenberg models. Using site-resolved periodic modulation of Rydberg states, we develop an experimentally feasible protocol to precisely control the interaction ratios $ J_2/J_1$ and $ J_3/J_1$ in a kagome lattice. This control can increase the effective range of interactions and drive transitions between competing spin-ordered and spin liquid phases. To generalize this approach beyond the kagome lattice, we reformulate the design of modulation patterns through a graph-theoretic approach, demonstrating the universality of our method across all 11 planar Archimedean lattices. Our strategy overcomes the inherent constraints of power-law-decaying dipolar interactions, providing a versatile toolbox for exploring frustrated magnetism, emergent topological phases, and quantum correlations in systems with long-range interactions.
Quantum Gases (cond-mat.quant-gas), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Atomic Physics (physics.atom-ph)
Observation of Half-Quantum Vorticity in an Iron-based Superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Mohammad Javadi Balakan, Genda Gu, Qiang Li, Kenji Watanabe, Takashi Taniguchi, Ji Ung Lee
Half-quantum vortices – topological excitations carrying half the superconducting flux quantum – are predicted to emerge in spin-triplet superconductors, where the spin component of order parameter enables fractional flux quantization. We present direct transport signatures of half-quantum vorticity in single-crystal Fe(Te,Se), an iron-based superconductor with helical Dirac surface states. Using mesoscopic superconducting ring devices, we observe half-integer quantum oscillations arising from the splitting of quantized fluxoid states, further supported by distinct signatures of trapped half-integer fluxoids. The quantum oscillations are modulated by a background symmetry, set by the relative orientation of the DC bias current and perpendicular magnetic field, consistent with strong spin-orbit coupling. These findings demonstrate the long-sought half-quantum vorticity in spin-polarized superconductors and open new directions toward non-Abelian excitations in quantum materials and scalable topological qubits.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Ferroelasticity, shear modulus softening, and the tetragonal-cubic transition in davemaoite
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Tianqi Wan, Chenxing Luo, Zhen Zhang, Yang Sun, Renata M. Wentzcovitch
Davemaoite (Dm), the cubic phase of CaSiO3-perovskite (CaPv), is a major component of the Earth’s lower mantle. Understanding its elastic behavior, including its dissolution in bridgmanite (MgSiO3-perovskite), is crucial for interpreting lower mantle seismology. Using machine-learning interatomic potentials and molecular dynamics, we investigate CaPv’s elastic properties across the tetragonal-cubic transition. Our equations of state align well with experimental data at 300 K and 2,000 K, demonstrating the predictive accuracy of our trained potential. We simulate the ferroelastic hysteresis loop in tetragonal CaPv, which has yet to be investigated experimentally. We also identify a significant temperature-induced shear modulus softening near the phase transition, characteristic of ferroelastic-paraelastic transitions. Unlike previous elasticity studies, our softening region does not extend to slab geotherm conditions. We suggest that ab initio-quality computations provide a robust benchmark for shear elastic softening associated with ferroelasticity, a challenging property to measure in these materials.
Materials Science (cond-mat.mtrl-sci)
Super-Universal Behavior of Outliers Diffusing in a Space-Time Random Environment
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
I characterize the extreme location and extreme first passage time of a system of $ N$ particles independently diffusing in a space-time random environment. I show these extreme statistics are governed by the Kardar-Parisi-Zhang (KPZ) equation and derive their mean and variance. I find the scalings of the statistics depend on the moments of the environment. Each scaling regime forms a universality class which is controlled by the lowest order moment which exhibits random fluctuations. When the first moment is random, the environment plays the role of a random velocity field. When the first moment is fixed but the second moment is random, the environment manifests as fluctuations in the diffusion coefficient. As each higher moment is fixed, the next moment determines the scaling behavior. Since each scaling regime forms a universality class, this model for diffusion forms a super-universality class. I confirm my theoretical predictions using numerics for a wide class of underlying environments.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
A Unified Simulation Framework for Correlated Driven-Dissipative Quantum Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Thomas Blommel, Enrico Perfetto, Gianluca Stefanucci, Vojtěch Vlček
Time-resolved photoemission spectroscopy provides a unique and direct way to explore the real-time nonequilibrium dynamics of electrons and holes. The formal theory of the spectral function evolution requires inclusion of electronic correlations and dissipation, which are challenging due to the associated long simulation timescales which translate to a high computational cost. Recent methodological developments, namely the Real-Time Dyson Expansion, as well as theoretical developments of many-body perturbation theory for dissipative systems, have allowed for the study of driven-dissipative interacting quantum systems. In this work, we implement the hitherto unrealized study of driven-dissipative interacting quantum systems which includes driven dynamical correlations and utilizes these new methods and perturbative expansions. We illustrate the combined formalism on a prototypical two-band semiconductor model with long-range density-density Coulomb interactions. We show that the intraband thermalization of conduction band electrons induces nontrivial time-dependent changes in the system’s bandstructure and a time-evolving band-gap renormalization (with a reduction by up to 10%). We show that the qualitative features are preserved for a variety of parameters, discuss the corresponding spectral dynamics, and provide an outlook on the newly introduced simulation framework, which enables treating electron-electron scattering and dissipation effects on equal footing.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Computational Physics (physics.comp-ph)
Robust electro-mechanical actuation in hydrogenated Xenes leading to reversible topological transition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Sujith Nedungattil Subrahmanian, Nabendu Mondal, Joydeep Bhattacharjee
We report from first principles, the possibility of reversible onset of topological insulator(TI) phase in heavier hydrogenated Xenes (Xane), namely, germanane and stanane, exclusively through in-plane electro-mechanical actuation. It is found possible to systematically induce robust uniaxial strain through non-uniform application of electric field in the plane of monolayers, as possible through application of in-homogeneous bias at gates of realizable length-scales embedded underneath. Electrically induced strain causes substantial lowering of band-gap across all Xanes, eventually evolving through weak followed by strong topologically insulating phases beyond a threshold degree of bias in-homogeneity in heavier Xanes, promisingly within the range of bias sustained by the monolayers. In case of nano-ribbons of these Xanes, bias applied in-homogeneously across width promises switchable emergence of TI phase over a fraction of width and topologically protected interface states localizable anywhere across the half-width of the ribbon. The demonstrated electro-mechanical actuation and the associated topological tuning of band-structure, thematically verified in gapped graphene based representative systems within the Kane-Mele model at half-filling, should be possible in the broader class of two dimensional covalent networks made of elements of the p-block.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
10 pages, 11 figures
Ultraviolet/infrared mixing-driven suppression of Kondo screening in the antiferromagnetic quantum critical metal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Francisco Borges, Peter Lunts, Sung-Sik Lee
We study a magnetic impurity immersed in the two-dimensional antiferromagnetic quantum critical metal (AFQCM). Critical spin fluctuations represented by a bosonic field compete with itinerant electrons to couple with the impurity through the spin-spin interaction. At long distances, the antiferromagnetic electron-impurity (Kondo) coupling dominates over the boson-impurity coupling. However, the Kondo screening is weakened by the boson with an increasing severity as the hot spots connected by the magnetic ordering wave-vector are better nested. For $ v_{0,i} \ll 1$ , where $ v_{0,i}$ is the bare nesting angle at the hot spots, the temperature $ T_K^{\mathrm{AFQCM}}$ below which Kondo coupling becomes $ O(1)$ is suppressed as $ \frac{\log \Lambda/T_K^{\mathrm{AFQCM}}}{\log \Lambda/T_K^{\mathrm{FL}}} \sim \frac{g_{f,i}}{v_{0,i} \log 1/v_{0,i} }$ , where $ T_K^{\mathrm{FL}}$ is the Kondo temperature of the Fermi liquid with the same electronic density of states, and $ g_{f,i}$ is the boson-impurity coupling defined at UV cutoff energy $ \Lambda$ . The remarkable efficiency of the single collective field in hampering the screening of the impurity spin by the Fermi surface originates from a ultraviolet/infrared (UV/IR) mixing: bosons with momenta up to a UV cutoff actively suppress Kondo screening at low energies.
Strongly Correlated Electrons (cond-mat.str-el)
14 pages
Probing fractional quantum Hall effect by photoluminescence
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Aamir A. Makki, Mytraya Gattu, J. K. Jain
The recent discovery of fractional quantum anomalous Hall (FQAH) states - fractional quantum Hall (FQH) states realized without an external magnetic field - in twisted transition-metal dichalcogenide (TMD) bilayers represents a significant development in condensed matter physics. Notably, these states were first observed via photoluminescence (PL) spectroscopy. Surprisingly, a general theoretical understanding of PL is not available even for the standard FQH states. For an ideal two-dimensional system, the energy of the emitted photon is predicted to be independent of the correlations, but we show that the PL intensity contains valuable information. Specifically, we predict that at finite temperatures, the PL intensity peaks at the Jain fillings \nu = n/(2n \pm 1), and away from these fillings, the binding energies of the composite-fermion excitons and trions can be deduced from the temperature dependence of the intensity. We discuss implications for PL experiments in semiconductor quantum wells and twisted TMD bilayers.
Strongly Correlated Electrons (cond-mat.str-el)
Analytical Gradient-Based Optimization of CALPHAD Model Parameters
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Courtney Kunselman, Brandon Bocklund, Richard Otis, Raymundo Arroyave
The calibration of CALPHAD (CALculation of PHAse Diagrams) models involves the solution of a very challenging high-dimensional multiobjective optimization problem. Traditional approaches to parameter fitting predominantly rely on gradient-free methods, which while robust, are computationally inefficient and often scale poorly with model complexity. In this work, we introduce and demonstrate a generalizable framework for analytic gradient-based optimization of the parameters of the CALPHAD model enabled by the recently formalized Jansson derivative technique. This method allows for efficient evaluation of gradients of thermodynamic properties at equilibrium with respect to model parameters, even in the presence of arbitrarily complex internal degrees of freedom. Leveraging these semi-analytic gradients, we employ the conjugate gradient (CG) method to optimize thermodynamic model parameters for four binary alloy systems: Cu-Mg, Fe-Ni, Cr-Ni, and Cr-Fe. Across all systems, CG achieves comparable or superior optimality relative to Bayesian ensemble Markov Chain Monte Carlo (MCMC) with improvements in computational efficiency ranging from one to three orders of magnitude. Our results establish a new paradigm for CALPHAD assessments in which high fidelity data-rich model calibration becomes tractable using deterministic gradient-informed algorithms.
Materials Science (cond-mat.mtrl-sci)
Effect of interatomic repulsion on a Kitaev-transmon qubit based on double quantum dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Clara Palacios ana Armando A. Aligia
We investigate the effect of interatomic Coulomb repulsion $ V$ on the Kitaev-transmon system proposed by Pino \textit{et al.} \cite{pino} which consists of a Josephson junction between two double quantum dots (DQDs) modeled by the spinless Kitaev Hamiltonian. For an isolated DQD, we demonstrate that a “sweet spot” hosting “poor man’s Majorana” states can still be achieved in the presence of $ V$ by appropriately tuning the system parameters. This adjustment allows the extension of previous results to the case of finite Coulomb repulsion $ V \neq 0$ . However, we observe modifications in the microwave spectrum, due to the presence of previously overlooked states. Additionally, we find that at the sweet spot of both DQDs, all eigenstates of the transmon system exhibit exact double degeneracy.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
5 pages without references, 5 figures
Leakage Suppression Across Temperature in Al1-xScxN Thin Film Ferroelectric Capacitors through Boron Incorporation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Pedram Yousefian, Xiaolei Tong, Jonathan Tan, Dhiren K. Pradhan, Deep Jariwala, Roy H. Olsson III
This paper presents high-temperature ferroelectric characterization of 40nm Al$ _{1-x-y}$ B$ _x$ Sc$ _y$ N (AlBScN) thin film capacitors grown by co-sputtering Al$ _{0.89}$ B$ _{0.11}$ and Sc targets onto Pt(111)/Ti(002)/Si(100) substrates. Structural analysis confirmed a c-axis-oriented wurtzite structure with a low surface roughness of 1.37nm. Ferroelectric switching, characterized by positive-up-negative-down (PUND) measurements up to 600$ ^\circ$ C, exhibited a linear decrease in coercive fields from 6.2MV/cm at room temperature to 4.2MV/cm at 600$ ^\circ$ C, while remanent polarization remained stable with temperature. Direct current I-V measurements highlight a significant suppression of leakage currents, over two orders of magnitude lower compared to AlScN capacitors fabricated under similar conditions. These results position AlBScN thin films as strong candidates for ferroelectric applications in extreme environments.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Topological Quantum Statistical Mechanics and Topological Quantum Field Theories
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
In this work, we first focus on the mathematical structure of the three-dimensional (3D) Ising model. In the Clifford algebraic representation, many internal factors exist in the transfer matrices of the 3D Ising model, which are ascribed to the topology of the 3D space and the many-body interactions of spins. They result in the nonlocality, the nontrivial topological structure, as well as the long-range entanglement between spins in the 3D Ising model. We review briefly the exact solution of the ferromagnetic 3D Ising model at the zero magnetic field, which was derived in our previous work. Then, the framework of topological quantum statistical mechanics is established, with respect to the mathematical aspects (topology, algebra, and geometry) and physical features (the contribution of topology to physics, Jordan-von Neumann-Wigner framework, time average, ensemble average, and quantum mechanical average). This is accomplished by generalizations of our findings and observations in the 3D Ising models. Finally, the results are generalized to topological quantum field theories, in consideration of relationships between quantum statistical mechanics and quantum field theories. It is found that these theories must be set up within the Jordan-von Neumann-Wigner framework, and the ergodic hypothesis is violated at the finite temperature. It is necessary to account the time average of the ensemble average and the quantum mechanical average in the topological quantum statistical mechanics and to introduce the parameter space of complex time (and complex temperature) in the topological quantum field theories. We find that a topological phase transition occurs near the infinite temperature (or the zero temperature) in models in the topological quantum statistical mechanics and the topological quantum field theories, which visualizes a symmetrical breaking of time inverse symmetry.
Statistical Mechanics (cond-mat.stat-mech)
51 pages, 3 figures
Symmetry, 14 (2022), 323
Room-Temperature Pauli Spin Blockade and Current Rectification in 15-13-15 Armchair Graphene Nanoribbon Heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
We investigate the electronic structures and charge transport properties of 13-11-13 and 15-13-15 armchair graphene nanoribbon (AGNR) superlattices using a tight-binding model. The conduction and valence subbands of the 15-13-15 AGNR superlattice are found to be accurately described by the Su-Schrieffer-Heeger (SSH) model, with topologically protected interface states forming at the junctions between 15- and 13-AGNR segments. We demonstrate that these interface states function as robust tunneling channels, behaving as a serial double quantum dot (SDQD) system under appropriate electrode coupling. Utilizing the two-site Anderson model with electron-electron interactions and Keldysh Green function formalism, we analyze nonlinear charge transport and reveal Coulomb blockade phenomena and charge stability diagrams consistent with experimental observations. Particular attention is given to temperature-dependent current rectification in the Pauli spin blockade (PSB) regime, where significant rectification is preserved under weak orbital offset conditions but suppressed under strong offset, replaced by thermally activated tunneling at room temperature. The tunability and resilience of SDQDs based on 15-13-15 AGNR heterostructures highlight their potential for spin-current conversion applications, with advantages in fabrication and parameter control offered by bottom-up synthesis techniques.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
32 pages and 13 Figures
Vortex States and Coherence Lengths in Flat-Band Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Chuang Li, Fu-Chun Zhang, Lun-Hui Hu
Superconductivity in flat-band systems, governed by quantum metric of Bloch states rather than the BCS framework, exhibits unique phenomena due to the vanishing electron group velocity. Here, we propose the vortex states and vortex size as direct probes to explore the quantum geometry effects in flat-band superconductors. We show that flat-band vortex bound states are sharply localized near the vortex core, and the energy gap between the lowest two bound states is on the order of the bulk superconducting gap. Both the spatial spread and energy scales of bound states are controlled by the flat-band’s quantum metric length. Moreover, the vortex size at zero temperature, set by the quantum metric length, is atomic in scale and independent of interaction strength. Near $ T_c$ , the vortex size corresponds to the Ginzburg-Landau coherence length, diverges as $ \xi\sim \sqrt{T_c/(T_c-T)}\xi_0$ , where $ \xi_0$ depends linearly on the quantum metric length. Thus, the quantum metric serves as the lower bound for vortex state spread and vortex size. We also introduce perturbations to make the flat band dispersive, and distinguish flat-band vortices from BCS-like vortices. Our results establish vortices as universal probes of quantum geometry in flat-band superconductors.
Superconductivity (cond-mat.supr-con)
Myosin-driven advection and actin reorganization control the geometry of confined actomyosin gel
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
Archit Negi, Ryota Sakamoto, Makito Miyazaki, Yusuke T. Maeda
Harnessing nanoscale motor proteins to actively control material shape is a promising strategy in nanotechnology and material science. One notable system is the actomyosin network, composed of actin filaments and myosin motor proteins, providing a natural platform for constructing contractile, shape-adaptive materials. While the role of actomyosin in shaping cells has been extensively studied, the reverse question - how boundary shape affects the actomyosin system - remains poorly understood. Here, we present a microfabricated system that reveals how geometrical confinement directs the organization of actomyosin networks within microwells. By combining experimental and numerical analysis, we show that the asymmetric shape of the microwells is transferred to contracted actomyosin gels via myosin-driven actin flow. Furthermore, tuning myosin contractility and actin polymerization rate allows control over the size and shape of actomyosin gels. Our findings provide a bottom-up framework for integrating molecular motors and cytoskeletons into confined architectures to create responsive biomaterials.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
22 pages, 5 figures
Transition from near-field to extreme near-field radiative heat transfer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Fridolin Geesmann, Philipp Thurau, Sophie Rodehutskors, Till Ziehm, Ludwig Worbes, Svend-Age Biehs, Achim Kittel
The radiative heat transfer in the extreme near-field regime, i.e. for distances below 10 nm, remains poorly understood. There are competing experimental results in this regime, with some in good agreement with theoretical predictions, while others report drastically elevated heat fluxes, orders of magnitude larger than what theory suggests. Whether the theory of fluctuational electrodynamics can predict the radiative heat transfer in this extreme near-field regime or not remains a matter of active debate. In this study, a radiative heat transfer measurement is presented between a gold-coated sphere and a gold film sample in the transition regime between the near-field and the extreme near-field regime just before contact. The radiative heat flux measurement is made by using a near-field scanning thermal microscope equipped with a temperature sensor at a sharp tip as a heat flux sensor. We find an excellent agreement with the theoretical predictions of fluctuational electrodynamics in the near-field regime. In the extreme near-field regime however, a highly increased radiative heat flux is observed with values about 100 times larger than the theoretical predictions, indicating that fluctuational electrodynamics fails to capture the radiative heat flux in this regime.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures
Polarization-Driven Charge Frustration and Emergent Phases in the One-Dimensional Extended Hubbard Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Sourabh Saha, Jeroen van den Brink, Manoranjan Kumar, Satoshi Nishimoto
Frustration is a key driver of exotic quantum phases, yet its role in charge dynamics remains largely unexplored. We show that charge frustration - induced by electronic polarization effects - stabilizes unconventional insulating states in the one-dimensional extended Hubbard model. Using exact diagonalization and density-matrix renormalization group, we uncover a charge-disordered phase that remains insulating despite lacking long-range order and possessing an effectively attractive on-site interaction - a behavior reminiscent of gapful spin liquids in frustrated spin systems. We also identify a fragile ferroelectric phase and a charge-density-wave state with emergent eight-site periodicity. These findings establish charge frustration, driven by charge-dipole interactions, as a robust mechanism for realizing exotic phases in low-dimensional correlated systems, with implications for organic conductors, transition-metal oxides, and ultracold polar molecules.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 5 figures
Unveiling the interplay of magnetic order and electronic band structure on the evolution of anomalous Hall effect in MnPtGa single crystal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Gourav Dwari, Shovan Dan, Bishal Baran Maity, Sitaram Ramakrishnan, Achintya Lakshan, Ruta Kulkarni, Vikash Sharma, Suman Nandi, Partha Pratim Jana, Andrzej Ptok, A. Thamizhavel
The recent studies on the anomalous Hall effect (AHE) have revealed an intrinsic relationship between the topological band structure and the experimentally observed transverse conductivity. Consequently, this has led to a heightened focus on examining the topological aspects of AHE. Here we have studied sign reversal of anomalous Hall conductivity with temperature in the single crystalline MnPtGa (space group: $ P6_3/mmc$ ). From the interdependence of the linear resistance, we claim that the origin of such behavior is intrinsic. By systematically studying the electronic band structure and Berry curvature of MnPtGa using first principle calculations supported by magnetic susceptibility and isothermal magnetization measurements we demonstrate that the temperature dependent complex magnetic structure plays a significant role and leads to the sign reversal of anomalous Hall conductivity. We proposed a continuous evolution of the magnetic structure, supported by the ab initio calculations, which is consistent with the experimental data. Our studies have established that the critical temperature ($ \approx$ 110 K), where the sign reversal appears is associated with the magnetic structure and the magnitude of Mn moments.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
14 pages, 5 figures
Phys. Rev. B 110, 045111 (2024)
Landau levels in Weyl semimetal under uniaxial strain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
The external strain can lead to the similar effect to the external applied magnetic field. Such pseudomagnetic field can be larger than typical magnetic fields, what gives the opportunity to experimentally study the Landau levels. In this paper we study the effects of uniaxial strain on the Weyl nodes, using continuum and lattice model. In the continuum model we show that the uniaxial strain leads to magnetic field renormalization, which in practice corresponds to the shift of the Landau levels to higher energy. We also investigate type-I and type-II Weyl nodes using lattice model. In this case, the magnetic field is introduced by the Pierels substitution, while uniaxial strain by the direction dependence of hopping integrals. This allowed us to probe the Landau level and system spectrum which takes form of Hofstadter butterfly. We show that the renormalization of magnetic field, similar to this observed in the continuum model, emerges.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
12 pages, 5 figures
Physica B 698, 416730 (2025)
Ferroelectrically Switchable Chirality in Topological Superconductivity: Bilayer-MnBi2Te4/Fe(Se,Te) Heterostructure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Kai-Zhi Bai, Bo Fu, Shun-Qing Shen
The interplay between ferroelectricity, magnetism, and superconductivity provides a rich platform for discovering novel quantum phenomena. Here, we propose a heterostructure composed of an antiferromagnetic bilayer MnBi2Te4 coupled with the s-wave superconductor Fe(Se,Te), enabling the realization of chiral topological superconductivity (CTSC) with switchable chirality. The chirality of the CTSC is controlled by the direction of spontaneous polarization, which arises from interlayer sliding-induced ferroelectricity or charge transfer in the bilayer MnBi2Te4. This sliding mechanism breaks the MzT and PT symmetries, leading to the anomalous Hall effect in the spin-polarized metallic Dirac band and drives the emergence of CTSC when the s-wave superconductivity appears. Our work not only provides a new pathway to achieve and control topological superconductivity but also opens avenues for experimental exploration of Majorana physics and topological quantum computation.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 6 figures
Tunable Chern Insulators in Moiré-Distant and Moiré-Proximal Rhombohedral Pentalayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Chushan Li, Zheng Sun, Kai Liu, Lei Qiao, Yifan Wei, Chuanqi Zheng, Chenyu Zhang, Kenji Watanabe, Takashi Taniguchi, Hao Yang, Dandan Guan, Liang Liu, Shiyong Wang, Yaoyi Li, Hao Zheng, Canhua Liu, Bingbing Tong, Li Lu, Jinfeng Jia, Zhiwen Shi, Jianpeng Liu, Guorui Chen, Tingxin Li, Xiaoxue Liu
Rhombohedral-stacked multilayer graphene aligned with hexagonal boron nitride has emerged as an excellent platform for investigating exotic quantum states arising from the interplay between electron correlations and topology. Here, we report the electrical transport properties of a rhombohedral pentalayer graphene/hexagonal boron nitride moiré device with a twist angle of 1.02° and a moiré period of approximately 10.1 nm. In this device, we observe anomalous Hall effects and integer Chern insulators in both moiré-proximal and moiré-distant regimes. Specifically, in the moiré-distant regime, an integer Chern insulator with Chern number C = 1 emerges at moiré filling {\nu} = 1 under a moderate magnetic field. In the moiré-proximal regime, we identify a rich set of topological and correlated phases near {\nu} = 1, including integer Chern insulator states with C = \pm 1 and trivial insulators, and they are highly sensitive to both the applied displacement field and magnetic field. Moreover, at {\nu} = 2 in the moiré-proximal regime, Chern insulators with C = \pm 1 has also been observed. Our results underscore the sensitivity of topological quantum states to the moiré potential strength and highlight the importance of twist-angle engineering in exploring novel quantum states in rhombohedral-stacked multilayer graphene moiré systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Decoding Vibrational Signatures of Molybdenum Sulphide Molecular Catalysts for Solar Hydrogen Evolution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Pardis Adams, Jan Bühler, Angel Labordet Alvarez, David Tilley, and Mirjana Dimitrievska
Molybdenum sulfide clusters, [Mo3S4]4+ and [Mo3S13]2-, have emerged as key molecular models for understanding active sites in Mo-S-based catalysts and as promising candidates for energy conversion applications. Despite their importance, comprehensive vibrational characterization of these clusters remains limited. Here, we present a detailed Raman and infrared spectroscopic analysis of both clusters, supported by density functional theory (DFT) calculations. High-quality crystalline samples were synthesized and characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) to confirm morphology and stoichiometry. Raman spectra, acquired using 488 nm and 532 nm laser excitation, were deconvoluted using Lorentzian fitting. Vibrational mode assignments were made through direct comparison with DFT predictions. For [Mo3S4]4+, major Raman bands appear near 200 cm^-1, 350 cm^-1, and 450 cm^-1, corresponding to Mo-S-Mo bending, Mo-S stretching, and terminal sulfur vibrations. [Mo3S13]2- shows two distinct spectral regions: 100-400 cm^-1 for Mo-S and S-S bending and stretching, and 450-550 cm^-1 for terminal disulfide (S-S) stretching. Complementary IR spectra calculations reveal additional vibrational features, yielding a more complete fingerprint for each cluster. Finally, we demonstrate that Raman spectroscopy offers greater sensitivity than X-ray diffraction (XRD) in detecting these clusters on supporting materials. This work provides a detailed vibrational reference for [Mo3S4]4+ and [Mo3S13]2-, establishing Raman and IR spectroscopy as powerful tools for characterizing Mo-S molecular clusters in both fundamental and applied contexts.
Materials Science (cond-mat.mtrl-sci)
Enhancing atomic-resolution in electron microscopy: A frequency-domain deep learning denoiser
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Ivan Pinto-Huguet, Marc Botifoll, Xuli Chen, Martin Borstad Eriksen, Jing Yu, Giovanni Isella, Andreu Cabot, Gonzalo Merino, Jordi Arbiol
Atomic resolution electron microscopy, particularly high-angle annular dark-field scanning transmission electron microscopy, has become an essential tool for many scientific fields, when direct visualization of atomic arrangements and defects are needed, as they dictate the material’s functional and mechanical behavior. However, achieving this precision is often hindered by noise, arising from electron microscopy acquisition limitations, particularly when imaging beam-sensitive materials or light atoms. In this work, we present a deep learning-based denoising approach that operates in the frequency domain using a convolutional neural network U-Net trained on simulated data. To generate the training dataset, we simulate FFT patterns for various materials, crystallographic orientations, and imaging conditions, introducing noise and drift artifacts to accurately mimic experimental scenarios. The model is trained to identify relevant frequency components, which are then used to enhance experimental images by applying element-wise multiplication in the frequency domain. The model enhances experimental images by identifying and amplifying relevant frequency components, significantly improving signal-to-noise ratio while preserving structural integrity. Applied to both Ge quantum wells and WS2 monolayers, the method facilitates more accurate strain quantitative analyses, critical for assessing functional device performance (e.g. quantum properties in SiGe quantum wells), and enables the clear identification of light atoms in beam sensitive materials. Our results demonstrate the potential of automated frequency-based deep learning denoising as a useful tool for atomic-resolution nano-materials analysis.
Materials Science (cond-mat.mtrl-sci)
20 pages, 5 Figures
Landau theory description of autferroicity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Jun-Jie Zhang, Boris I. Yakobson, Shuai Dong
Autferroics, recently proposed as a sister branch of multiferroics, exhibit strong intrinsic magnetoelectricity, but ferroelectricity and magnetism are mutually exclusive rather than coexisting. Here, a general model is considered based on the Landau theory, to clarify the distinction between multi and autferroics by qualitative change-rotation in Landau free energy landscape and in particular phase mapping. The TiGeSe$ _3$ exemplifies a factual material, whose first-principles computed Landau coefficients predict its autferroicity. Our investigations pave the way for an alternative avenue in the pursuit of intrinsically strong magnetoelectrics.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Friedel Oscillations in a Two-Dimensional Electron Gas and Monolayer Graphene with a Non-Coulomb Impurity Potential
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
We study Friedel oscillations in a two-dimensional non-interacting electron gas and in a monolayer graphene in the presence of a single impurity. The potential generated by the impurity is modeled using a non-Coulomb interaction ($ \sim r^{-\eta}$ ). The charge carrier density deviation as a function of distance from the impurity is calculated within the linear response theory. Our results show that, in both a two-dimensional non-interacting electron gas and graphene, the phase of charge carrier density oscillations remains unaffected by the parameter $ \eta$ , which characterizes the non-Coulomb nature of the interaction, at large distances from the impurity. The parameter $ \eta$ influences only the amplitude of the oscillations in this regime. The results for an impurity modeled by Coulomb-like potential ($ \eta = 1$ ) are recovered in both cases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 3 figures
Strain-Balanced Low-Temperature-Grown Beryllium-Doped InGaAs/InAlAs Superlattices for High-Performance Terahertz Photoconductors under 1550 nm Laser Excitation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Milad Entezami, Seyed Ali Hosseini Farahabadi, Man Chun Alan Tam, Andree Coschizza, Jan Kycia, Zbigniew R. Wasilewski
This study systematically investigates the photoconductive properties of low-temperature-grown Beryllium (Be)-doped InGaAs/InAlAs strain-balanced superlattices (SLs) grown by molecular beam epitaxy under stationary growth conditions on semi-insulating InP:Fe substrates. The stationary growth approach enabled precise control over lateral gradients in layer strain, composition, and thickness across a single wafer, while strain-balancing facilitated pseudomorphic growth to explore a wide range of structural parameters, providing a robust platform to study their influence on photoconductive performance. Structural characterization confirmed high crystalline quality and smooth surface morphology in all samples. Time-resolved pump-probe spectroscopy revealed subpicosecond carrier lifetimes, validating the effectiveness of strain balancing and Be doping in tuning ultrafast recombination dynamics. Hall effect measurements supported by 8-band k.p modeling revealed enhanced carrier mobility in strain-balanced SLs compared to lattice-matched structures, primarily due to reduced electron and hole effective masses and stronger quantum confinement. Additionally, optical absorption under 1550 nm excitation showed improved absorption coefficients for the strain-balanced structure, consistent with the reduction in bandgap energy predicted by theoretical modeling, thereby enhancing photon-to-carrier conversion efficiency. Furthermore, transmission electron microscopy provided first-time evidence of significant Be-induced interdiffusion at the strained SL interfaces, an important factor influencing carrier transport and dynamics. These findings position low-temperature-grown Be-doped InGaAs/InAlAs strain-balanced SLs as promising materials for high-performance broadband THz photoconductive detectors operating at telecom-compatible wavelengths.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Braided mixing in confined chiral active matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
Efficient mixing of fluids is essential in many practical applications to achieve homogeneity. For microscopic systems, however, both diffusion and turbulence are ineffective methods to achieve chaotic mixing due to the low Reynolds number, hence either active stirring or inducing turbulence through geometric boundary effects are generally implemented. Here, we study a modified chiral Vicsek model, where active microswimmers act as moving rods, stirring the surrounding substrate. We study the degree of mixing in the patterns formed by interplay between confinement, chiral motion and alignment interactions. This mixing is computed by considering the entanglement of spacetime trajectories of the particles, which forms a braid. Optimising the finite-time braiding exponent of this braid then yields a set of constituent parameters of the system, showing that a pattern consisting of a local stable vortex droplet and an ordered oscillating phase achieves the highest degree of mixing.
Soft Condensed Matter (cond-mat.soft), Chaotic Dynamics (nlin.CD)
9 pages, 9 figures
Parameter Sensitivity Analysis in Zinc-Ion Batteries: A Study on Ionic Conductivity, Current Density, and Electrode Properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Roya Rajabi, Shichen Sun, Booker Wu, Jamil Khan, Kevin Huang
This study presents a comprehensive Multiphysics model for zinc-ion batteries (ZIBs), incorporating electrochemical aspects. The model integrates the mass transport of Zn2+ ions, charge transfer, and solid diffusion to predict performance parameters like cell potential, and energy density. Significant research has focused on enhancing battery performance by optimizing components of battery to improve parameters such as ionic conductivity and exchange current density and capacity. In this study, we present a model-based investigation of zinc-ion batteries, examining the impact of these parameters. Our findings reveal that at low current densities, raising of ionic conductivity beyond 1.3 S/m and exchange current density above 0.13 mA/cm2 do not yield substantial improvements in capacity. These insights underscore the importance of identifying performance thresholds in the development of next-generation batteries.
Materials Science (cond-mat.mtrl-sci), Systems and Control (eess.SY)
Towards Sustainable Energy Storage: Evaluating Polymer Electrolytes for Zinc Ion Batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Roya Rajabi, Shichen Sun, Booker Wu, Jamil Khan, Kevin Huang
Polymer electrolytes present a promising solution to the challenges posed by aqueous electrolytes in energy storage systems, offering the flexibility needed for wearable electronics. Despite the increasing interest in polymer electrolyte-based zinc ion batteries (ZIBs), their development is still in its early stages due to various challenges. In this study, we fabricated three promising polymer electrolytes: CSAM (carboxyl methyl chitosan with acrylamide monomer), PAM (polyacrylamide monomer hydrogel electrolyte), and p-PBI (Phosphoric acid (PA)-doped polybenzimidazole) with Zn(ClO4)2 and Zn(OTf)2, for their application in zinc ion batteries. Our results demonstrated that PAM hydrogel electrolyte exhibited very low LDH formation after a long cycle, demonstrating effective protection for zinc foil, and the high mechanical stability of the p-PBI membrane provided prolonged durability against short circuits through the formation of LDH. The presence of carboxyl groups in CSAM and the formation of O-H bonding facilitated ion movement, resulting in enhanced ionic conductivity, and preventing dendrite formation. Incorporating these hydrogels with high-performance zinc salts, such as zinc triflate (Zn(OTf)2), resulted in impressive stability, with the symmetric cell demonstrating over 4000 hours of uniform and stable voltage profile under 1 mA/cm2 and low overpotential of around 53 mV cycling with CSAM. The full-cell battery with PBI-T membrane showed the highest durability and capacity compared to CSAM-T and PAM-T, due to the greater availability of free protons for storing zinc in the cathode.
Materials Science (cond-mat.mtrl-sci), Systems and Control (eess.SY)
Atomistic insight into the effects of solute and pressure on phase transformation in titanium alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Huicong Chen, Chenwei Shao, Zhuocheng Xie, Jun Song, Yu Zou
The phase stability and transformation between hexagonal close-packed (hcp) {\alpha}-phase and body-centered cubic (bcc) \b{eta}-phase in titanium (Ti) alloys are critical to their mechanical properties and manufacturing processes for engineering applications. However, many factors, both intrinsic and extrinsic (e.g., solute elements and external pressures, respectively), may govern their phase transformations dynamically, which is crucial to the design of new Ti alloys with desirable properties. In this work, we study the effects of various solute elements and external hydrostatic pressures on the solid-state phase transformations in Ti alloys using density functional theory (DFT) and nudged elastic band (NEB) calculations. The results show that both alloying and applied pressure reduce transformation barriers, with Al and Mo being most effective under ambient conditions, while Nb, V, Zr, and Sn show enhanced transformation kinetics under stress. Solute-induced modifications to the local electronic structure and bonding environment, particularly under pressure, contribute to variations in phase stability. We identify a synergistic interaction between solute effects and external stress, which facilitates phase transitions that are unachievable under static conditions. These findings provide atomistic insights into the coupled chemical-mechanical mechanisms underlying phase transformations in Ti alloys with improved phase stability and mechanical performance.
Materials Science (cond-mat.mtrl-sci)
Polar Indirect Valley as a Limiting Factor for Radiative Efficiency in Gold-Based Mixed-Valence Double Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Ange B. Chambissie Kameni, Alexandre Py-Renaudie, Damien Garrot, Baptiste Berenguier, Guillaume Bouchez, Davide Raffaele Ceratti, Philip Schulz, Jean-François Guillemoles, Géraud Delport
Double perovskites have emerged as promising alternatives to lead halide perovskites, aiming to mitigate challenges related to toxicity and chemical instability. Among them, mixed-valence gold halides such as Cs2Au+Au3+Cl6, which contain only a single type of metal cation in two oxidation states, stand out due to their unique structural and electronic properties. These materials exhibit strong absorption in the near-infrared range, making them attractive candidates for optoelectronic applications such as photovoltaics. In this work, we employ temperature-dependent optical spectroscopy techniques to demonstrate that these compounds exhibit particularly strong polar electron-phonon coupling, which has a profound impact on their optoelectronic properties. In particular, this coupling gives rise to a temperature-dependent absorption tail that reshapes the global spectral spectrum. We show that this tail leads to a forbidden band-egde recombination, which explains the reported difficulties in detecting a photoluminescence signal from this class of double perovskites.
Materials Science (cond-mat.mtrl-sci)
4 figures, 28 pages
Ferroelectric Switching in Hybrid Molecular Beam Epitaxy-Grown BaTiO3 Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Anusha Kamath Manjeshwar, Zhifei Yang, Chin-Hsiang Liao, Jiaxuan Wen, Steven J. Koester, Richard D. James, Bharat Jalan
Molecular beam epitaxy (MBE) is a promising synthesis technique for both heterostructure growth and epitaxial integration of ferroelectric BaTiO3. However, a direct measurement of the remnant polarization (P_r) has not been previously reported in MBE-grown BaTiO3 films. We report the in-situ growth of an all-epitaxial SrRuO3/BaTiO3/SrRuO3 heterostructure on Nb-doped SrTiO3 (001) substrates by hybrid MBE using metal-organic precursors. This capacitor structure consisting of 16 nm SrRuO3/40 nm BaTiO3/16 nm SrRuO3 shows hysteretic polarization-electric field (P-E) curves with P_r = 15 {\mu}C cm-2 at frequencies ranging from 500 Hz to 20 kHz, after isolating the intrinsic ferroelectric response from non-ferroelectric contributions using the Positive-Up-Negative-Down (PUND) method. We hypothesize that the asymmetry in switching behavior and current leakage has origins in structural defects.
Materials Science (cond-mat.mtrl-sci)
30 pages, 4 figures
New quantum state formed by highly concentrated protons in superconducting palladium hydride
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Ryoma Kato, Ten-ichiro Yoshida, Riku Iimori, Tai Zizhou, Masanobu Shiga, Yuji Inagaki, Takashi Kimura, Koichiro Ienaga, Tatsuya Kawae
Hydrogen exhibits quantum phenomena, such as tunneling in materials. According to theory, the quantum properties of hydrogen change significantly in superconductors due to the emergence of an energy gap on the Fermi surface, which reduces the interaction between hydrogen nucleus (i.e., proton) and conduction electrons. This reduction is predicted to enhance the tunneling probability of protons. Here, we report the double transitions of the electrical resistivity in high-quality palladium hydride (PdHx) and deuteride (PdDx) prepared by low-temperature absorption below T = 180 K. After a sharp drop in the resistivity at T ~ 2 K owing to the superconducting transition of PdH(D)x, a large residual resistivity remained. Additionally, the resistivity dropped to zero below T = 1 K. The experimental results suggest that the quantum tunneling of highly concentrated protons (deuterons) in the superconducting state is responsible for the observed features: the residual resistivity arises from the weakening of the global coherence of superconductivity owing to the tunneling motion of protons (deuterons), while the zero resistivity is caused by long-range ordering of the protons (deuterons). This system offers a new platform for investigating the quantum many-body properties of tunneling particles.
Superconductivity (cond-mat.supr-con)
Altermagnetic type-II Multiferroics with Néel-order-locked Electric Polarization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Wen-Ti Guo, Junqi Xu, Huaiqiang Wang, Haijun Zhang
Altermagnetism, an emergent magnetic phase featuring compensated collinear magnetic moments and momentum-dependent spin splittings, has recently garnered widespread interest. A pivotal issue concerns whether the unconventional spin structures can generate spontaneous electric polarization in altermagnets, thereby achieving type-II multiferroicity. Here, with the combination of symmetry analysis and microscopic theory, we explicitly demonstrate the generation of electric polarization by altermagnetic Néel order, and establish a microscopic mechanism of Néel-order-locked electric polarization in altermagnetic multiferroics. We further reveal these pronounced magnetoelectric coupling behaviors and classify them into eight distinct categories for two-dimensional altermagnets governed by layer group symmetries. Then we take monolayer MgFe$ _2$ N$ _2$ as a prototypical example of altermagnetic multiferroics by first-principles calculations. We also propose to identify the Néel order orientation and accompanying electric polarization in altermagnetic multiferroics by magneto-optical microscopy. Bridging type-II multiferroics and altermagnets, our work could pave the way for altermagnetic multifunctional spintronics.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
Quasi-BICs due to symmetry mismatch in architected elastic plates
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Adib Rahman, Sean Perkins, Raj Kumar Pal
We report the existence of quasi-bound modes in the continuum (quasi-BICs) in architected elastic plates based on a square lattice. The structure consists of topologically trivial and nontrivial lattices, forming an interface and maintaining C2 symmetry. Carefully engineered interface gives rise to center quasi-BICs. We show how the mismatch in symmetry between the Bloch modes of the lattice and the defect modes confine them at the defect center, resulting in quasi-BICs. Our analysis begins with a square lattice-based spring-mass system. Finite element simulations on an architected plate comprising of slender curved and straight beams to achieve the desired stiffness variation predict quasi-BICs analogous to those in the discrete model. These predictions are validated with Laser Doppler vibrometry based experiments, confirming the presence of a quasi-BIC in the structure. The concept of quasi-BICs arising from modal symmetry mismatch paves the way for achieving localized modes in elastic structures, with potential applications as resonators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Probing quantum geometric capacitance via photonic spin Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Yahir Fernández-Méndez, Ramón Carrillo-Bastos, Jesús A. Maytorena
The non-dissipative quasistatic longitudinal optical response of insulators is characterized by an intrinsic geometric capacitance, determined by the ratio of the quantum metric to the energy gap, as recently stablished. We study the photonic spin Hall effect (PSHE) in this low-frequency regime, induced by reflection from an atomically thin material serving as the interface between two dielectrics. As a function of the magnitude of this geometric capacitance, covering values typical of graphene-family systems and for incidence close to the Brewster angle, the calculated in-plane and transverse beam shifts become comparable to the wavelength and thus detectable. At sufficiently low frequencies, we derive linear and quadratic approximations that allow the geometric capacitance to be extracted from measurements of the beam displacements. We provide an upper bound for the beam shifts. The results suggest that THz PSHE might be a useful probe of the quantum geometric capacitance of two-dimensional insulators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 4 figures
Nonlinear spin and orbital Rashba-Edelstein effects induced by a femtosecond laser pulse: Simulations for Au(001)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Oliver Busch, Franziska Ziolkowski, Börge Göbel, Ingrid Mertig, Jürgen Henk
Rashba-type spin-orbit coupling gives rise to distinctive surface and interface phenomena, such as spin-momentum locking and spin splitting. In nonequilibrium settings, one of the key manifestations is the (Rashba-)Edelstein effect, where an electric current generates a net spin or orbital polarization perpendicular to the current direction. While the steady-state behavior of these effects is well studied, their dynamics on ultrafast timescales remain largely unexplored. In this work, we present a theoretical investigation of the ultrafast spin and orbital Edelstein effects on an Au(001) surface, triggered by excitation with a femtosecond laser pulse. These effects are intrinsic and inherently nonlinear. Using a real-space tight-binding model combined with time evolution governed by the von Neumann equation, we simulate the electron dynamics in response to the pulse. Our results reveal pronounced differences between the spin and orbital responses, offering detailed insights into their distinct temporal profiles and magnitudes. We further explore the associated charge, spin, and orbital currents, including the emergence of laser-induced spin and orbital Hall effects. Finally, we quantify the angular momentum transfer mediated by the light-matter interaction. These findings shed light on the intricate ultrafast dynamics driven by spin-orbit coupling and offer guidance for the design of next-generation spintronic and orbitronic devices.
Materials Science (cond-mat.mtrl-sci)
Exact diagonalization study of triangular Heisenberg model with four-spin ring-exchange interaction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Yuchao Zheng, Muwei Wu, Dao-Xin Yao, Han-Qing Wu
Using Lanczos exact diagonalization (ED), we study the spin-1/2 $ J_1$ -$ J_2$ Heisenberg model with the four-spin ring-exchange interaction $ J_r$ on triangular lattice. We mainly use the level spectroscopic technique of two 36-site tori to investigate the ground-state phase diagram, and further characterize phases by spin, dimer and chiral correlation functions. The ground state has rich phases including several magnetic ordered phases like zigzag phase and tetrahedral phase, as well as several novel nonmagnetic phases, some of which exhibit valence bond solid behavior in their dimer correlation functions. However, we do not find direct evidence of a quantum spin liquid phase with spinon Fermi surface in this model. Our results can give a better understanding of the ground-state properties of the triangular Heisenberg model with ring-exchange interaction, and help to understand the relevant triangular materials.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 11 figures
Dynamical dimerization and subdiffusive transport of strongly correlated neutral-ionic systems coupled to lattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
We study the Monte Carlo dynamics of strongly correlated classical particles coupled to lattice degrees of freedom that exhibit the neutral-ionic transitions in one dimension, relevant to the organic compounds TTF-CA and TTF-BA. The particles carrying up and down spins suffer strong Coulomb interactions and undergo a neutral-to-ionic transition when the alternating site potentials become small, accompanying the charge transfer to the higher energy sites. The model is already shown to exhibit the enhancement of conductivity near the neutral-to-ionic crossover, which is carried by the neutral-ionic domain walls (NIDWs) that show diffusive character. Here, by incorporating local lattice dimerization effects, the motion of NIDWs becomes subdiffusive, and the conductivity is enhanced by one order of magnitude. When the ionic and dimerized states coexist, the strong fluctuation of dimer configuration supports the antiferromagnetic spin correlation, suppresses Pauli blocking, and subsequently enhances the motion of NIDWs. Our results highlight the crucial role of local and fluctuating dimerization in governing transport and ferroelectric properties near neutral-ionic transitions.
Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 10 figures
Nonvolatile Cryogenic Phase Slip Memory with Single-Shot Readout
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Lukas Nulens, Davi A. D. Chaves, Stijn Reniers, Ruben Dillemans, Ivo P. C. Cools, Kristiaan Temst, Bart Raes, Margriet J. Van Bael, Joris Van de Vondel
The demand for cryogenic memory components is driven by the need for ultra-fast, low-power, and highly reliable computing systems. Phase slip-based devices promise to fulfill all these requirements, with potential applications in both classical and quantum information processing. However, previous implementations have faced challenges due to inefficient writing and readout schemes. In this work, we address these limitations with a simple device design and measurement techniques inspired by circuit quantum electrodynamics. We present a memory element that stores information in the winding of a high-kinetic inductance superconducting loop, inductively coupled to a coplanar waveguide resonator. Using single-shot measurements, we achieve a readout fidelity of 99.698% with an active measurement time of just 25 ns.
Superconductivity (cond-mat.supr-con)
Main; 7 pages, 4 figures Supp; 4 pages, 4 figures
Three types of condensation in open wedges
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
Jiří Janek, Alexandr Malijevský
Condensation in linear wedges formed by semi-infinite walls is a well-established critical phenomenon characterized by the continuous growth of an adsorbed liquid layer as bulk two-phase coexistence is approached. In this study, we investigate condensation in finite-length wedges open at both ends, demonstrating that the process becomes first-order. The open boundaries and finite geometry induce a remarkably rich phase behavior of the confined fluid, exhibiting three distinct types of condensation, reentrant phenomena, and continuous higher-order transitions between condensation states. Through a detailed macroscopic analysis, we derive the conditions for each type of condensation, classify the global phase diagrams, and explore asymptotic behavior in specific limiting cases. The asymptotic predictions are confirmed by a detailed comparison with the numerical solutions of the governing equations.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Phys. Rev. E. 111, 045507 (2025)
How to Train an Oscillator Ising Machine using Equilibrium Propagation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-06 20:00 EDT
We show that Oscillator Ising Machines (OIMs) are prime candidates for use as neuromorphic machine learning processors with Equilibrium Propagation (EP) based on-chip learning. The inherent energy gradient descent dynamics of OIMs, combined with their standard CMOS implementation using existing fabrication processes, provide a natural substrate for EP learning. Our simulations confirm that OIMs satisfy the gradient-descending update property necessary for a scalable Equilibrium Propagation implementation and achieve 97.2(1)% test accuracy on the MNIST dataset without requiring any hardware modifications. Importantly, OIMs maintain robust performance under realistic hardware constraints, including moderate phase noise and 10-bit parameter quantization. These results establish OIMs as a promising platform for fast and energy-efficient neuromorphic computing, potentially enabling energy-based learning algorithms that have been previously constrained by computational limitations.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
4 pages, 3 figures, 1 table
Translational-Symmetry-Broken Magnetization Plateaux of the $S=3/2$ Anisotropic Antiferromagnetic Chain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Tomohide Kawatsu, Haruto Suzuki, Masaru Hashimoto, Koki Doi, Tomoki Houda, Rito Furuchi, Hiroki Nakano, Kiyomi Okamoto, Tôru Sakai
The magnetization process of the $ S=3/2$ quantum spin chain with the $ XXZ$ anisotropy and the single-ion anisotropy $ D$ is investigated using the numerical diagonalization of finite-size clusters and the level spectroscopy analysis. We obtain the phase diagrams at 1/3 and 2/3 of the saturation magnetization to find that the translational-symmetry-broken magnetization plateau appears for the first time. The similarity and the difference between the phase diagrams of the present model and the related models are discussed by use of the discrete parameters of the models. In addition several typical magnetization curves are presented.
Strongly Correlated Electrons (cond-mat.str-el)
to be published in J. Phys. Soc. Jpn
Diffuson-Dominated Thermal Transport Crossover from Ordered to Liquid-like Cu$_3$BiS$_3$:The Negligible Role of Ion Hopping
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Jincheng Yue, Jiongzhi Zheng, Xingchen Shen, Chun-Chuen Yang, Shuyao Lin, Yanhui Liu, Tian Cui
Fundamentally understanding lattice dynamics and thermal transport behavior in liquid-like, partially occupied compounds remains a long-standing challenge in condensed matter physics. Here, we investigate the microscopic mechanisms underlying the ultralow thermal conductivity in ordered/liquid-like Cu$ _3$ BiS$ _3$ by combining experimental methods with first-principles calculations. We first experimentally synthesize and characterize the ordered structure and liquid-like, partially Cu-atom occupied Cu$ _3$ BiS$ _3$ structure with increasing temperature. We then combine self-consistent phonon calculations, including bubble-diagram corrections, with the Wigner transport equation, considering both phonon propagation and diffuson contributions, to evaluate the anharmonic lattice dynamics and thermal conductivity in phase-change Cu$ _3$ BiS$ _3$ . Our theoretical model predicts an ultralow thermal conductivity of 0.34 W/m/K at 400 K, dominated by diffuson contributions, which accurately reproduces and explains the experimental data. Importantly, the machine-learning-based molecular dynamics (MD) simulations not only reproduced the partially Cu-atom occupied Cu$ _3$ BiS$ _3$ structure with the space group $ \mathrm{P2_12_12_1}$ but also successfully replicated the thermal conductivity obtained from experiments and Wigner transport calculations. This observation highlights the negligible impact of ionic mobility arising from partially occupied Cu sites on the thermal conductivity in diffuson-dominated thermal transport compounds. Our work not only sheds light on the minimal impact of ionic mobility on ultralow thermal conductivity in phase-change materials but also demonstrates that the Wigner transport equation accurately describes thermal transport behavior in partially occupied phases with diffuson-dominant thermal transport.
Materials Science (cond-mat.mtrl-sci)
Construction of First Principle Based Adiabatic and Diabatic Hamiltonian for TiO$_6^{8-}$ unit of BaTiO$_3$ Crystal: Photoemission Spectra and Ferroelectricity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Mantu Kumar Sah, Soumya Mukherjee, Satyam Ravi, Satrajit Adhikari
The ferroelectric property of BaTiO$ 3$ crystal arises from the strong Pseudo Jahn-Teller (PJT) interactions between the non-degenerate ground electronic state, $ ^1A{1g}$ and the degenerate $ ^1T_{1u}$ symmetry states through the nuclear distortions of $ t_{1u}$ modes in TiO$ 6^{8-}$ unit. In a $ d^0$ electronic configuration of $ Ti^{4+}$ ion, the PJT interaction leads to a stabilization effect, which has been explored using Beyond Born-Oppenheimer (BBO) theory. The $ ^1T{1u}$ excited states form a three-state degeneracy, exhibiting feeble Jahn-Teller (JT) distortions over the $ t_{2g}$ planes. For the first time, we compute \textit{ab initio} adiabatic potential energy surfaces (PESs) and non-adiabatic coupling terms (NACTs), and thereafter, diabatic PESs and couplings for the perovskite unit, TiO$ _6^{8-}$ . Using a Time-Dependent Discrete Variable Representation (TDDVR) approach, the theoretical photoemission spectra exhibit good agreement with the experimental ones. Moreover, the experimental observation on order parameter associated with ferroelectric properties of BaTiO$ _3$ crystal show close resemblance with present and other theoretical predictions.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Quantum Physics (quant-ph)
Optimizing proximitized magnetic topological insulator nanoribbons for Majorana bound states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Eduárd Zsurka, Daniele Di Miceli, Julian Legendre, Llorenç Serra, Detlev Grützmacher, Thomas L. Schmidt, Kristof Moors
Magnetic topological insulator (MTI) nanoribbons proximitized by an $ s$ -wave superconductor (PNRs) are a potential platform for the practical realization of Majorana bound states (MBSs). As with all MBS platforms, disorder and device imperfections can be detrimental to the formation of robust and well-separated MBSs that are suitable for fusion and braiding experiments. Here, we identify the optimal conditions for obtaining a topological superconducting gap that is robust against disorder, with spatially separated stable MBSs in PNRs, and introduce a figure of merit that encompasses these conditions. Particular attention is given to the thin-film limit of MTIs, where the hybridization of the surface states cannot be neglected, and to the role of electron-hole asymmetry in the low-energy physics of the system. Based on our numerical results, we find that (1) MTI thin films that are normal (rather than quantum spin Hall) insulators for zero magnetization are favorable, (2) strong electron-hole asymmetry causes the stability and robustness of MBS to be very different for chemical potentials above or below the Dirac point, and (3) the magnetization strength should preferably be comparable to the hybridization or confinement energy of the surface states, whichever is largest.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Topological Surface States of 3D Topological Insulator on Twisted Bilayer Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
We present a comprehensive theoretical study of the topological surface states (TSS) of Bi$ _2$ Se$ _3$ , a 3D topological insulator, epitaxially grown on twisted bilayer graphene (tBG). The moiré potential induced by tBG folds the TSS Dirac cone into the moiré Brillouin zone (MBZ), resulting in mini-gap openings, band flattening, and the potential emergence of secondary Dirac points. Using effective field theory, symmetry analysis, and higher-order perturbation theory, we analyze both commensurate and incommensurate twist angles, revealing significant band structure reconstruction in periodic systems and quasi-periodic effects in incommensurate ones. This work provides deep insights into the interplay between topological protection and moiré modulation, offering a pathway to engineer novel topological phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
11 pages
Unraveling the storage mechanism of Na${3}$V${2-x}$Ni$_x$(PO$_4$)$_2$F$_3$/C cathodes for sodium-ion batteries through electrochemical, {\it operando} X-ray diffraction and microscopy studies
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Simranjot K. Sapra, Jeng-Kuei Chang, Rajendra S. Dhaka
The storage mechanism and diffusion kinetics of Na$ _{3}$ V$ _{2-x}$ Ni$ _{x}$ (PO$ _{4}$ )$ _{2}$ F$ _{3}$ /C ($ x=$ 0–0.07) cathodes are investigated through electrochemical impedance spectroscopy (EIS), galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV). All the samples are prepared through the facile pH-assisted sol-gel route and crystallize in the P4$ _{2}$ /mnm symmetry. The optimal doping of Ni ($ x=$ 0.05) exhibits superior specific capacities of 119 and 100 mAh g$ ^{-1}$ at 0.1 C and 10 C rates, respectively, along the excellent capacity retention of 78% after 2000 cycles at 10 C rate with nearly 100% Coulombic efficiency. The apparent diffusion coefficient values are found to be in the range of 10$ ^{-9}$ –10$ ^{-10}$ cm$ ^{2}$ s$ ^{-1}$ through detailed analysis of CV and GITT. Moreover, we report the reversible structural evolution and morphological changes during charging and discharging under non-equilibrium conditions through the {\it operando} X-ray diffraction and the {\it in-situ} synchrotron based transmission X-ray microscopy, respectively. Further, to understand the stability mechanism and obtain precise polarization values, we performed the distribution of relaxation times (DRT) analysis using the EIS data. The structure and morphology are found to be stable after long cycling.
Materials Science (cond-mat.mtrl-sci)
submitted
Impurity dynamics in a zero-temperature gas
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
Umesh Kumar, Abhishek Dhar, P. L. Krapivsky
If energy is suddenly released in a localized region of space uniformly filled with identical stationary hard spheres of radii $ a$ , the outcome is a blast with an asymptotically spherical shock wave separating moving and stationary hard spheres. The radius of the region filled with the moving spheres grows as $ R\sim (E t^2/n_\infty)^{1/(d+2)}$ , where $ d$ is the spatial dimension, $ n_\infty$ the number density of stationary spheres and $ E$ is the total energy injected. The simplest way to inject energy is to kick a few `impurity’ particles. Using hydrodynamics and kinetic theory, we argue that the typical displacement of an impurity scales as $ R_{\rm imp} \sim \lambda (R/\lambda)^{(4+3d^2)/(8+3d^2)}$ , where $ \lambda\sim 1/(n_\infty a^{d-1})$ is the mean-free path in the initial state. The number of collisions experienced by each impurity is $ (R/\lambda)^{(8+2d^2)/(8+3d^2)}$ , while its average speed decreases as $ t^{-d(8-2d+3d^2)/[(2+d)(8+3d^2)]}$ . In $ 2D$ , the predictions for impurity displacement, collision numbers, and speed are $ t^{2/5},~t^{2/5}$ and $ t^{-2/5}$ , respectively. These predictions are in reasonable agreement with the results of molecular dynamics simulations.
Statistical Mechanics (cond-mat.stat-mech)
9 Pages, 3 Figures
Many-body critical phase in a quasiperiodic chain and dynamical Widom lines in Fock space properties
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-06 20:00 EDT
Nilanjan Roy, Subroto Mukerjee, Sumilan Banerjee
We study a quasiperiodic model in one dimension, namely the extended Aubry-André-Harper (EAAH) chain, that realizes a critical phase comprising entirely single-particle critical states in the non-interacting limit. In the presence of short-range interactions, the non-interacting critical phase transforms to a many-body critical (MBC) phase, separated by lines of MBC-ergodic, MBC-many-body localized (MBL) and ergodic-MBL phase transitions that meet at a triple point. We elucidate the unusual characteristics of the MBC phase compared to the ergodic and MBL phases through the localization properties of the excitations in real space and Fock space (FS), and eigenstate inverse participation ratio (IPR). We show that the MBC phase, like the MBL phase, is well described by a multifractal scaling of the IPR and a linear finite-size scaling ansatz near the transition to the ergodic and MBL phases. However, the MBC phase, at the same time, exhibits delocalization of all single-particle excitations and a system-size dependent Fock-space localization length, analogous to the ergodic phase. Remarkably, we find evidence of unusual Widom lines on the phase diagram in the form of lines of pronounced peaks or dips in the FS localization properties inside the MBC and MBL phases. These Widom lines either emerge as a continuation of the precursor phase transition line, terminating at the triple point, or originate from a phase boundary.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
17 pages, 18 figures
Comparing the performance of direct and parametric drives for piezoelectric MEMS actuators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
This work investigates and compares the response of piezoelectrically actuated nonlinear microelectromechanical devices (MEMS) to direct and to degenerate parametric drives. We describe the regime of degenerate parametric amplification in piezoelectric Duffing-type nonlinear MEMS devices using a single mode expansion, we then explore the existence of regions in parameter space where parametric excitation maybe advantageous compared to direct drive, which we label “parametric advantage”. Analytical, experimental, and numerical verification demonstrates that parametric advantage can not exist if both pump and signal voltages are accounted for in the total voltage budget. This work determines non-dimensional scaling rules that can act as guidelines for selecting an optimal operating regime for degenerate parametric amplification.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Two-dimensional M2X2 family with emerging semiconducting, semimetallic, and magnetic properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Yasin Yekta, Hamidreza Ramezani, Hanif Hadipour, Seyed Akbar Jafari
The exploration for novel two-dimensional (2D) materials with diverse electronic characteristics has attracted growing interest in recent years. Using density functional theory (DFT) calculations, we have predicted a new family of 2D transition-metal (TM) based compounds under the nomenclature M_2X_2 (where M represents TMs, and X denotes chalcogen elements like S, Se, and Te). Our investigation delves into the examination of the formation energies, dynamical/thermal stabilities, mechanical properties, electronic structures, and magnetic properties of various systems within this family. Through our computational analyses, we have discovered a total of 35 thermodynamically and dynamically stable M_2X_2 monolayer materials that exhibit remarkable diversity in terms of their electronic and magnetic properties. Our findings will pave the way for the experimental realization of various M_2X_2 structures in the near future. In particular, among the predicted compounds, M_2X_2(M=Zn, Cd; X=S, Se, Te) are a direct band-gap semiconductor with band gaps between 0.9 to 2.6 eV (1.3 to 3.7 eV) by DFT+PBE (hybrid functional HSE) calculations. M_2X_2(M=Ti, Zr, Hf, Tc, Re) are zero-gap semiconductor (semimetals) in standard DFT+PBE calculation. Inclusion of spin-orbit coupling leads to a gap opening of 0.1 eV. Notably, our analysis has also unveiled the magnetic nature of certain materials, such as Mn_2X_2(X=S, Se), Fe_2X_2(X=Se, Te), and Ti_2Te_2. The prediction of semiconducting (magnetic) M_2X_2 materials not only offers valuable insights into the underlying electronic properties (magnetism) of 2D systems but also positions these materials as promising candidates for the development of advanced electronic (spintronic) devices.
Materials Science (cond-mat.mtrl-sci)
16 pages, 7 figures
Time-Reversal Symmetry Protected Transport at Correlated Oxide Interfaces
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Mengke Ha, Qing Xiao, Zhiyuan Qin, Dawei Qiu, Longbing Shang, Xinyi Liu, Pu Yan, Changjian Ma, Danqing Liu, Chengyuan Huang, Zhenlan Chen, Haoyuan Wang, Chang-Kui Duan, Zhaoliang Liao, Wei-Tao Liu, Yang Gao, Kecheng Cao, Jiangfeng Du, Guanglei Cheng
Time-reversal symmetry (TRS) protection is core to topological physics, yet its role in correlated oxides-typically non-topological-remains underexplored. This limit hampers the potential in engineering exotic quantum states by fusing TRS protection and the rich emergent phenomena in the oxide platform. Here, we report evidence of a TRS-protected subband at oxygen vacancy-free LaAlO3/SrTiO3 interfaces. This subband causes a low-field quantum oscillation with anomalous characters: exceptionally light electron mass, aperiodicity, and susceptibility to magnetic fields. All findings align with a Rashba model in which TRS-protected transport occurs along quasi-1D ferroelastic domain walls, which possess a Dirac band topology and a giant Rashba spin-orbit coupling, two orders stronger than the 2D interface. Our results deepen the understanding of SrTiO3-based electron systems, unveiling an appealing new platform for quantum engineering.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Simple scaling rules governing work functions of two-dimensional materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
James C. Ellenbogen, Sahasra Yellepeddi, Zev Goldhaber-Gordon
This paper demonstrates that values of work functions W for a variety of planar and buckled two-dimensional (2D) materials scale linearly as a function of the quantity 1/r_{WS}, where r_{WS} is the Wigner-Seitz radius for a 2D material. Simple procedures are prescribed for estimating r_{WS}. Using them, this linear scaling relation, which is founded in electrostatics, provides a quick and easy method for calculating values of W from basic, readily available structural information about the materials. These easily determined values of W are seen to be very accurate when compared to values from the literature. Those derive from experiment or from challenging, computationally intensive density-functional-theory calculations. Values from those sources also conform to the linear scaling rules. Since values of W predicted by the rules so closely match known values of W, the simple scaling methods described here also are applied to predict W for 2D materials (TiN, BSb, SiGe, and GaP) for which no values have appeared previously in the literature.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Half-Ice, Half-Fire Driven Ultranarrow Phase Crossover in 1D Decorated q-State Potts Ferrimagnets: An AI-Co-Led Discovery
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
OpenAI’s reasoning model o3-mini-high was used to carry out an exact analytic study of one-dimensional ferrimagnetic decorated $ q$ -state Potts models. We demonstrate that the finite-temperature ultranarrow phase crossover (UNPC), driven by a hidden “half-ice, half-fire” state in the $ q=2$ Potts (Ising) model, persists for $ q>2$ . We identify novel features for $ q>2$ , including the dome structure in the field-temperature phase diagram and for large $ q$ a secondary high-temperature UNPC to the fully disordered paramagnetic state. The ice-fire mechanism of spin flipping can be applied to higher-dimensional Potts models. These results establish a versatile framework for engineering controlled fast state-flipping switches in low-dimensional systems. Our nine-level AI-contribution rating assigns AI the meritorious status of AI-co-led discovery in this work.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 5 figures. A sequel to arXiv:2502.11270 and arXiv:2503.23758
Interfacial superconductivity in Cu/Cu$_{\rm{2}}$O and its effect on shielding ambient electric fields
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Dale R. Harshman, Anthony T. Fiory
A model is presented for two-dimensional superconductivity at semiconductor-on-metal interfaces mediated by Coulomb interactions between electronically-active interface charges in the semiconductor and screening charges in the metal. The junction considered is native Cu$ _{\rm{2}}$ O on Cu in which an interfacial double charge layer of areal density $ n$ , comprising superconducting holes in Cu$ {\rm{2}}$ O and mediating electrons in Cu, is induced in proportion to a sub-monolayer of adsorbed $ ^{\rm{4}}\rm{He}$ atoms. Evidence for superconductivity on copper with prior air exposure is revealed in new analysis of previously published work function data. Based on a theory developed for layered superconductors, the intrinsic transition temperature $ T{\rm{C}}$ = $ \beta$ $ n$ ^{\rm{1/2}}$ /$ \zeta$ is determined by $ n$ and transverse distance $ \zeta$ $ \simeq$ 2.0 $ \rm{Å}$ between the charge layers; $ \beta$ = 1.933(6) $ e$ ^{\rm{2}}$ \bar{\lambda}$ {\rm{C}}$ /k$ {\rm{B}}$ = 1247.4(3.7) K-$ \rm{Å}$ ^{\rm{2}}$ is a universal constant involving the reduced Compton wavelength of the electron $ \bar{\lambda}$ {\rm{C}}$ . This model is applied to understanding the shielding of copper work-function patch and gravitational compression electric fields reported in the Witteborn-Fairbank gravitational electron free fall experiment. Interfacial superconductivity with $ n$ $ \simeq$ 1.6 $ \times$ 10$ ^{\rm{12}}$ $ \rm{cm}^{\rm{-2}}\rm{,}$ $ T{\rm{C}}$ $ \simeq$ 7.9 K and Berezinskiĭ-Kosterlitz-Thouless temperature $ T{\rm{BKT}}$ $ \simeq$ 4.4 K accounts for the shielding observed at temperature $ T$ $ \simeq$ 4.2 K. Helium desorption and concomitant decreases in $ n$ and $ T{\rm{C}}$ replicate the temperature transition in ambient electric fields on falling electrons, as observed by Lockhart et al., and the vanishing of superconductivity above $ T$ $ \simeq$ 4.8 K.
Superconductivity (cond-mat.supr-con)
20 pages, 9 figures, 18 equations, 111 references
Physica C: Superconductivity and its Applications 632, 1354600 (2025)
A universal scaling law for active diffusion in complex media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
Qun Zhang, Yuxin Tian, Xue Zhang, Xiaoting Yu, Hongwei Zhu, Ning Zheng, Luhui Ning, Ran Ni, Mingcheng Yang, Peng Liu
Using granular experiments and computer simulations, we investigate the long-time diffusion of active tracers in a broad class of complex media composed of frozen obstacles of diverse structures. By introducing a dimensionless persistence length $ Q = v_d \tau_r / d_t$ , we propose a modified scaling relation that independently collapses experimental and simulation results across active and passive particles, diverse media, and distinct propulsion mechanisms. Our results reveal a universal active diffusion-structure relation that holds across both equilibrium and nonequilibrium regimes, providing a simple predictive framework for active diffusion in complex environments.
Soft Condensed Matter (cond-mat.soft)
2D van der Waals magnets: from fundamental physics to applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Je-Geun Park, Kaixuan Zhang, Hyeonsik Cheong, Jae Hoon Kim, Carina Belvin, David Hsieh, Honglie Ning, Nuh Gedik
Magnetism has played a central role in the long and rich history of modern condensed matter physics, with many foundational insights originating from theoretical studies of two-dimensional (2D) spin systems. The discovery of 2D van der Waals (vdW) magnets has revolutionized this area by providing real, atomically thin magnetic systems for experimental investigation. Since the first experimental reports of antiferromagnetic vdW insulators in 2016 - followed by studies on ferromagnetic vdW systems in 2017 - the field has witnessed rapid and expansive growth, with more than two dozen vdW magnetic materials now identified, including both ferro- and antiferromagnets. In this review, we present a comprehensive overview of the major scientific and technological developments in this rapidly evolving field. These include experimental realizations of various 2D spin Hamiltonians as well as unexpected phenomena such as magnetic excitons, Floquet-engineered states, and light-induced metastable magnetic phases. In parallel, 2D vdW magnets have shown significant promise in spintronics and related applications, offering a new platform for engineering quantum functionalities. We organize this review by tracing the historical development of the field, synthesizing key milestones, and highlighting its broader impact across condensed matter physics and materials science. We conclude with an Outlook section that outlines several promising directions for future research, aiming to chart a path forward in this vibrant and still rapidly growing area.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
83 pages, 33 figures, Submitted to Review of Modern Physics
Electrical generation of surface plasmon polaritons in plasmonic heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Surface plasmon polaritons (SPPs) can be understood as two-dimensional light confined to a conductor-dielectric interface via plasmonic excitations. While low-energy SPPs behave similarly to photons, higher-frequency SPPs resemble surface plasmons. Generating mid-range SPPs is particularly challenging due to their momentum mismatch with photons and energy mismatch with plasmons. Here, we theoretically demonstrate that graphene’s ability to sustain a high bias and support a strongly non-equilibrium steady-state electron-hole population enables near-infrared SPP generation in plasmonic van der Waals heterostructures composed of undoped monolayer graphene, hexagonal boron nitride (hBN), and silver (Ag). We show that this mechanism requires neither optical gratings nor electron tunneling to produce non-thermal, bias-tunable SPP emission, which is uniform along the Ag-hBN interface and achieves an internal conversion efficiency of up to $ 10^{-3}$ with the Purcell factor of up to 100. These findings pave the way for integrating photonic and electronic functionalities within a single two-dimensional heterostructure.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
5 pages, 4 figures, and 12 pages of supporting material
Learning simple heuristic rules for classifying materials based on chemical composition
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
In the past decade, there has been a significant interest in the use of machine learning approaches in materials science research. Conventional deep learning approaches that rely on complex, nonlinear models have become increasingly important in computational materials science due to their high predictive accuracy. In contrast to these approaches, we have shown in a recent work that a remarkably simple learned heuristic rule – based on the concept of topogivity – can classify whether a material is topological using only its chemical composition. In this paper, we go beyond the topology classification scenario by also studying the use of machine learning to develop simple heuristic rules for classifying whether a material is a metal based on chemical composition. Moreover, we present a framework for incorporating chemistry-informed inductive bias based on the structure of the periodic table. For both the topology classification and the metallicity classification tasks, we empirically characterize the performance of simple heuristic rules fit with and without chemistry-informed inductive bias across a wide range of training set sizes. We find evidence that incorporating chemistry-informed inductive bias can reduce the amount of training data required to reach a given level of test accuracy.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG), Chemical Physics (physics.chem-ph)
10 pages, 3 figures
Translational Symmetry Broken Magnetization Plateau of the $S={1}\over{2}$ Anisotropic Spin Ladder with Ferromagnetic Rung Interaction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Tôru Sakai, Koki Doi, Kiyomi Okamoto, Kouichi Okunishi, Masaru Hashimoto, Tomoki Houda, Rito Furuchi, Hiroki Nakano
The magnetization process of the $ S=1/2$ anisotropic spin ladder with the ferromagnetic rung interaction is investigated using the numerical diagonalization of finite-size clusters. It is found that the translational symmetry broken magnetization plateau would appear at half the saturation magnetization, when the competing anisotropies are sufficiently large. The phase diagram with respect to the anisotropies and several magnetization curves are presented.
Strongly Correlated Electrons (cond-mat.str-el)
Proceedings of ICM 2024, to be published in Journal of Physics: Conference Series
Magnetization Plateau of the $S={1 \over 2}$ Distorted Diamond Spin Chain with Ferromagnetic Interaction
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Masaru Hashimoto, Koki Doi, Tomoki Houda, Rito Furuchi, Hiroki Nakano, Kiyomi Okamoto, Tôru Sakai
The magnetization process of the $ S=1/2$ distorted diamond spin chain with ferromagnetic interactions is investigated using the numerical diagonalization of finite-size clusters. The level spectroscopy analysis applied for the model with the spin anisotropy indicates that two different magnetization plateau phases appear at 1/3 of the saturation magnetization. The phase diagrams for some typical interaction parameters are presented. In addition the magnetization curves for several typical parameters are obtained.
Strongly Correlated Electrons (cond-mat.str-el)
Proceedings of ICM2024, to be published in Journal of Physics: Conference Series
A Unified Theory of Unusual Anisotropic Magnetoresistance and Unidirectional Magnetoresistance in Nanoscale Bilayers
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Nanoscale bilayers containing at least one magnetic layer exhibit universal unusual anisotropic magnetoresistance (UAMR) and unidirectional magnetoresistance (UMR). They are currently understood through various mechanisms related to the interconversion of charge current and spin current, giant magnetoresistance, thermal magnonic effects, thermoelectric effects, and diverse spindependent scattering processes. This raises a fundamental question: do the universal behaviors observed in a wide range of systems stem from underlying general principles? We demonstrate here that both UAMR and UMR arise from electron transport influenced by the magnetization vector present in the magnetic material and the interfacial potential inherent in heterostructures. Specifically, UAMR represents current-independent resistance (resistivity) of bilayers. UMR is the resistance proportional to the current although electron transports of the bilayers are the linear response to high current densities and their induced thermal gradients. Our theory introduces a novel approach that considers the interplay between the magnetization vector, thermal gradients, and the effective internal electric field at the interface. This framework provides a unified explanation for both UMR and UAMR, effectively capturing key experimental features such as dependence on current direction, magnetization orientation, film thickness, and magnetic field strength. Furthermore, it offers a universal perspective that bridges UMR and UAMR effects, enhancing our understanding of spin-dependent transport phenomena in bilayers.
Strongly Correlated Electrons (cond-mat.str-el)
Field Theory of Superconductor and Charged Vortex
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Yoonbai Kim, SeungJun Jeon, Hanwool Song
A Lagrangian of a Schrödinger type complex scalar field of Cooper pair, a U(1) gauge field of electromagnetism, and a neutral scalar field of acoustic phonon with constant background charge density is proposed for an effective field theory of conventional superconductivity. We find static charged vortex solutions of finite energy and, for the critical couplings of the quartic self-interaction coupling of complex scalar field and the cubic Yukawa type coupling between neutral and complex scalar field, these charged vortices saturate the BPS (Bogomolny-Prasad-Sommerfield) bound, that guarantees the nonperturbative classification of type I and II superconductors.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
8 pages, 2 figures
Non-equilibrium transport and phonon branch-resolved size effects based on a multi-temperature kinetic model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Chuang Zhang, Houssem Rezgui, Meng Lian, Hong Liang
Non-equilibrium transport and phonon branch-resolved size effects in single-layer graphene materials are studied under a multi-temperature kinetic model, which is developed for capturing the branch-dependent electron-phonon coupling. Compared with typical macroscopic multi-temperature models, the assumption of diffusive phonon transport is abandoned in this model and replaced by the free migration and scattering of particles. The phonon branch- and size-dependent effective thermal conductivity is predicted in nanosized graphene as well as the temperature slips near the boundaries. Compared with other phonon branches, the ZA branch contributes the most to thermal conduction regardless of system sizes. Furthermore, in nanosized homogeneous graphene with a hotspot at the center, the branch-dependent thermal conductivity increases from the inside to the outside even if the system size is fixed. The thermal conductivity of ZA branch is even higher than the lattice thermal conductivity when the system size is hundreds of nanometers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 4 figures
High-Throughput GW Calculations via Machine Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Ragab. A.Abdelghany, Chih-En Hsu, Hung-Chung Hsueh, Yuan-Hong Tsai, Ming-Chiang Chung
We present a machine learning (ML) framework that predicts $ G_0W_0$ quasiparticle energies across molecular dynamics (MD) trajectories with high accuracy and efficiency. Using only DFT-derived mean-field eigenvalues and exchange-correlation potentials, the model is trained on 25% of MD snapshots and achieves RMSEs below 0.1 eV. It accurately reproduces k-resolved quasiparticle band structures and density of states, even for BN polymorphs excluded from the training data. This approach bypasses the computational bottlenecks of $ G_0W_0$ simulations over dynamic configurations, offering a scalable route to excited-state electronic structure simulations with many-body accuracy.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
7 pages, 5 figures, 1 supplementary material
Molecular-sized bubbles in a liquid: free energy of formation beyond the capillarity approximation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
We investigate the transient bubbles that spontaneously appear in a simple liquid using molecular simulations. The objective is to deduce the free-energy of formation of the bubbles $ W(s)$ from the bubble size distribution $ p(s)$ through the hypothesis of a Boltzmann distribution: $ W(s) = -kT \ln p(s)$ . The bubbles are detected and characterized using a method based on a grid superimposed on the liquid, efficient for bubbles larger than the grid mesh. We first investigate how the results are affected by the mesh choice, and show that using several mesh values allows to detect bubbles in a wide range of sizes with minimal computing cost. The free-energy of formation of a bubble can then be deduced for a large range of sizes, with particular emphasis in the region of vanishing bubbles scarcely investigated in previous works. We first show that the usual Boltzmann relation has to be modified when the bubble size is characterized by its volume. In particular, the bubble volume distribution diverges for a vanishing bubble, which should be taken into account before calculating its free-energy of formation from the above formula. An analytical expansion, valid for any interacting spherical molecules, confirms this observation. We then show that the capillarity approximation fails for small bubbles: an extra contribution, linear with the bubble radius, has to be added to the usual quadratic (surface) and cubic (volume) contributions to the free-energy. This extra term most probably relates to the irregular shape of the tiny bubbles.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Hole-spin qubits in germanium beyond the single-particle regime
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Andrea Secchi, Gaia Forghieri, Paolo Bordone, Daniel Loss, Stefano Bosco, Filippo Troiani
The intense simulation activity on hole-spin qubits in Ge has focused so far on singly occupied quantum dots. Here, we theoretically investigate three-hole qubits in germanium and show that their performances compare well with those of their single-hole counterparts, both in strained and unstrained systems. In particular, enhancements of the gating times by two orders of magnitude are obtained in slightly elongated quantum dots. We show that, depending on the confinement anisotropy, such an enhancement is driven either by the occupation of excited spin-orbitals (Pauli principle), or by a Coulomb-induced charge rearrangement.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
4 pages + bibliography, 3 figures
Characterizing spin ordering via maximal row correlation in classical spin models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
Yong-Yi Tang, Yin Zhong, Hantao Lu
An order parameter, termed the maximal row correlation, is proposed for classical spin systems. Monte Carlo simulations on various Potts models suggest that this order parameter is applicable to a broad range of spin systems, including those defined on irregular lattices, systems with frustration, and systems exhibiting partial orders, provided some degree of spin ordering is present. This approach offers a unified framework for investigating phase transitions in such complex systems. The associated critical exponents are estimated via finite-size scaling analysis and show good agreement with established values.
Statistical Mechanics (cond-mat.stat-mech)
11 pages, 13 figures, including appendix
Electron density modulation in monolayer $MoS_{2}$ along the phase transition of a relaxor ferroelectric substrate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
D. Hernández-Pinilla, D. Cachago, Y. A. Xia, G. López-Polín, M. O Ramírez, L. E. Bausá
The integration of transition metal dichalcogenides (TMDs) with ferroelectric substrates is a powerful strategy to modulate their electronic and optical properties. However, the use of relaxor ferroelectrics for this purpose remains unexplored. Here, we demonstrate a reversible photoluminescence (PL) and charge density modulation of monolayer $ MoS_{2}$ on a $ Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}$ (SBN) substrate, a prototypical relaxor ferroelectric. The smearing of the phase transition in SBN enables continuous tuning of $ MoS_{2}$ electronic properties over a broad temperature range ($ 30-90°C$ ). A pronounced PL enhancement occurs as the substrate transitions from ferro-to-paraelectric phase due to the vanishing spontaneous polarization and the consequent change in charge balance at the $ MoS_{2}-SBN$ interface. Moreover, thermal hysteresis in the electron density modulation is observed during heating and cooling cycles. These findings highlight the potential of relaxor ferroelectrics as reconfigurable platforms for electron doping and light-emission control in 2D materials, opening avenues for temperature-responsive optoelectronic and nanophotonic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, 5 figures
Interaction-Driven Intervalley Coherence with Emergent Kekulé Orbitons
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
The $ p$ -orbital doublet in a honeycomb lattice is concretely studied with interacting spinless fermions at half filling. The Dirac fermions with linear dispersion at $ \pm K$ valleys govern the non-interacting low-energy physics. In the weak-coupling regime, the Dirac fermions are gaped due to the spontaneous generation of mass terms through a uniform axial orbital ordering, rendering the system into the quantum anomalous Hall insulator phase with a nonzero Chern number. Surprisingly, the intermediate many-particle interaction produces the intervalley coherence between $ \pm K$ valleys by developing complex polar orbital orderings in a tripled Wigner-Seitz cell. This phase is shown to have a deep connection with the low-energy physical behavior described by the orbital exchange model in the Mott insulating phase. The classical ground-state manifold in the Mott regime enjoys a continuous symmetry characterized by the intervalley coherent phase. Finally, the quantum fluctuation selects a unique ground state with emergent Kekulé orbitons through the order-by-disorder mechanism. Our findings provide insights for a direction of searching for Kekulé distortion in correlated multi-orbital systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
9 pages, 5 figures
Theoretical limits of electron and hole doping in single layer graphene from DFT calculations
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
Dawid Ciszewski, Wojciech Grochala
Density functional theory calculations suggest a pronounced hole electron doping asymmetry in a single layer graphene. It turns out that a single graphene sheet can sustain doping levels up to 0.1 holes or up to a remarkably large 1.9 electrons per atom while maintaining dynamical [phonon] stability. Estimates of the superconducting critical temperature in the electron doped regime based on McMillans formula reveal two local maxima in the function of doping level which correlate with the local maxima of the electron phonon coupling constant.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
3 pages, 4 figures, and supplement of 7 pages
Electrons as intermediate charge carriers in ion transport through nanoscale channels
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Baptiste Coquinot, Mathieu Lizée, Lydéric Bocquet, Nikita Kavokine
The ionic conductivity of a nanofluidic channel is one of its most basic properties, which is systematically characterized in experiments. While most studies to date have focused on the DC conductivity, there has recently been a surge of interest in the behavior of nanochannels under AC voltages. Here, we show that in nanochannels with electrically conducting walls, electrons can contribute to transporting ionic current through the channel. We identify a critical frequency and lengthscale above which electrons in the channel walls become the main charge carriers, resulting in a strongly increased conductivity. Our findings open the way to the engineering of nanofluidic functionalities based on ion-electron coupling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Machine-learning interatomic potentials from a users perspective: A comparison of accuracy, speed and data efficiency
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Niklas Leimeroth, Linus C. Erhard, Karsten Albe, Jochen Rohrer
Machine learning interatomic potentials (MLIPs) have massively changed the field of atomistic modeling. They enable the accuracy of density functional theory in large-scale simulations while being nearly as fast as classical interatomic potentials. Over the last few years, a wide range of different types of MLIPs have been developed, but it is often difficult to judge which approach is the best for a given problem setting. For the case of structurally and chemically complex solids, namely Al-Cu-Zr and Si-O, we benchmark a range of machine learning interatomic potential approaches, in particular, the Gaussian approximation potential (GAP), high-dimensional neural network potentials (HDNNP), moment tensor potentials (MTP), the atomic cluster expansion (ACE) in its linear and nonlinear version, neural equivariant interatomic potentials (NequIP), Allegro, and MACE. We find that nonlinear ACE and the equivariant, message-passing graph neural networks NequIP and MACE form the Pareto front in the accuracy vs. computational cost trade-off. In case of the Al-Cu-Zr system we find that MACE and Allegro offer the highest accuracy, while NequIP outperforms them for Si-O. Furthermore, GPUs can massively accelerate the MLIPs, bringing them on par with and even ahead of non-accelerated classical interatomic potentials (IPs) with regards to accessible timescales. Finally, we explore the extrapolation behavior of the corresponding potentials, probe the smoothness of the potential energy surfaces, and finally estimate the user friendliness of the corresponding fitting codes and molecular dynamics interfaces.
Materials Science (cond-mat.mtrl-sci)
Compositional disorder in a multicomponent non-reciprocal mixture: stability and patterns
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
Laya Parkavousi, Suropriya Saha
The mean compositions of individual components can be tuned to control phase behavior in number-conserving passive mixtures. In this work, we investigate the role of variable average density in a system of infinitely many non-reciprocally interacting scalar densities, within the framework of the multi-species non-reciprocal Cahn-Hilliard (NRCH) model. Rather than focusing on specific parameter choices, we study ensembles of systems where the inter-species interaction coefficients and average densities are sampled from probability distributions. We show that non-reciprocity stabilizes the homogeneous mixed state even in the presence of compositional disorder. Using random matrix theory, we derive a general condition for the onset of spinodal instability, which we verify through simulations. Finally, we illustrate the connection between the statistics of the most unstable eigenvalue and the emergent nonlinear dynamics.
Statistical Mechanics (cond-mat.stat-mech)
Efficient Computation of the Long-Range Exact Exchange using an Extended Screening Function
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Sebastian Kokott, Volker Blum, Matthias Scheffler
We introduce a computationally efficient screening for the Coulomb potential that also allows calculating approximated long-range exact exchange contributions with an accuracy similar to an explicit full-range evaluation of the exact exchange. Starting from the screening function of the HSE functional, i.e., the complementary error function, as zeroth order, a first-order Taylor expansion in terms of the screening parameter {\omega} is proposed as an approximation of the long-range Coulomb potential. The resulting extended screening function has a similar spatial extend as the complementary error function leading to a computational speed comparable to screened hybrid functionals such as HSE06, but with long-range exact exchange contributions included. The approach is tested and demonstrated for prototypical semiconductors and organic crystals using the PBE0 functional. Predicted energy band gaps, total energies, cohesive energies, and lattice energies from the first-order approximated PBE0 functional are close to those from the unmodified PBE0 functional, but are obtained at significantly reduced computational cost.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Studying the Seebeck coefficient and exploring the possibility of enhancing ZT upto 1.8 for NaCo$_2$O$_4$ in high temperature region
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Here, we have studied the temperature dependent Seebeck coefficient (S) of the NaCo$ _2$ O$ _4$ (NCO) by using experimental and computational methods. The range of experimentally obtained S is $ \sim$ 55 to 103 $ \mu$ V/K in the temperature range of 300-600 K, which confirms the p-type behaviour of NCO. The electronic structure of this compound is obtained via DFT+U formalism. The band dispersion and partial density of states confirms the magnetic and half metallic nature. Furthermore, in the transport properties, the obtained S using a U = 4 eV gives the best match with experimental data. The temperature and chemical potential dependent S$ ^{2}$ \sigma$ /$ \tau$ is calculated using the obtained electronic transport properties, in which the maximum value obtained for p(n)-type doping is $ \sim$ 22(61)$ \times$ 10$ ^1$ ^4$ $ \mu$ WK$ ^{-2}$ cm$ ^{-1}$ s$ ^{-1}$ . The possibility of enhancing the ZT is identified, and it is calculated in temperature range 300-1200 K. The maximum calculated value of ZT is 0.64 for p-type and 1.8 for n-type doping at 1200 K. The calculated carrier concentration obtained for p(n) type doping at 1200 K is $ \sim$ 1.17 (1.6)$ \times$ 10$ ^2$ ^2$ cm$ ^-$ ^3$ . This study suggests that the careful doping of p and n type can enhance the applicability of this compound in thermoelectric for high temperature application.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Hidden Quantum State and Signature of Mott Transition in Two-dimensional 1T-TaS2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Vivek Kumar, Birender Singh, Pradeep Kumar
Here we report a comprehensive inelastic light scattering studies on 1T-TaS2 with different thickness. This compound is well known for its rich charge density wave phases. Along with that it has been one of the promising candidates for a quantum spin liquid state as the spins reside on a triangular lattice and it does not show any signature of magnetic ordering. We performed a thickness dependent Raman measurement in a regime of completely commensurate charge density wave (C-CDW) to a nearly commensurate charge density wave (NC-CDW) with varying temperature (4K-330K) and polarization direction of the incident light. We observed the signature of CDW transition and in addition to that we have also found the signature of a well sought hidden quantum CDW state at low temperature around TH ~ 80K. The emergence of CDW, both normal and hidden one, is marked by the emergence of new phonon modes and distinct renormalized phonon self-energy parameters for the most prominent modes. A transition from metallic to the Mott insulating state is gauged via the Raman response using low frequency slope , reflected in the renormalized slope below TCDW and TH.
Strongly Correlated Electrons (cond-mat.str-el)
Anomalous valley Hall effect in monolayer chromium-based triple-Q magnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Xiu-Cai Jiang, Li-Ya Qiao, Yu-Zhong Zhang
Using the density functional theory calculations, we predict that several monolayer chromium-based materials exhibit a triple-Q tetrahedral magnetic insulating ground state. By studying the effect of biaxial strain on monolayer CrSi$ \rm{_2}$ P$ \rm{_4}$ under various on-site Coulomb interactions, we reveal that this magnetic insulating state, sandwiched between the itinerant $ 120^{\circ}$ coplanar noncollinear antiferromagnetic and ferromagnetic states, originates from the competition between antiferromagnetic exchange and double exchange interactions of Cr 3$ d$ electrons which can also be applied to account for the ground states in other chromium-based materials. Remarkably, anomalous valley Hall effect with giant valley splitting is discovered in the magnetic states of these inversion-asymmetric systems without requiring spin-orbit coupling or net magnetization. Our findings open a new avenue towards exploring monolayer materials for valleytronics.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Computational Physics (physics.comp-ph)
8 pages, 4 figures
Phys. Rev. B 111, L140416 (2025)
Statistics within UV-Visible Absorption Spectrum of Ethanolic Azobenzene
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-06 20:00 EDT
Eemeli A. Eronen, Johannes Niskanen
We report a statistical simulation of the UV-visible absorption spectrum of trans-azobenzene in ethanol solution. Due to intermolecular interactions, the used explicit solvent environment necessitates accounting for numerous transitions for a spectrum covering the two energetically lowest lines, S1 and S2. Furthermore, the spectrum manifests vast variation as a function of the underlying local structure, in conjunction with previous observations for spectra of liquids in the X-ray regime. We disentangle the complex structure-spectrum relationship using a machine learning-based method known as the emulator-based component analysis. This structural decomposition outperforms commonly used principal component analysis in explained spectral variation and reveals a small subset of latent structural variables responsible for the total spectral variance. Among other structural characteristics, blueshifting of the S2 line occurs with fewer hydrogen bonds with the ethanol solvent, and a contracted N-N bond within the C-N=N-C bridge. The observed structural dependence of the absorption spectrum thus implies an overrepresentation of certain structural classes after a photoexcitation, potentially significant for the subsequent nuclear dynamics, photophysics, and photochemistry.
Soft Condensed Matter (cond-mat.soft), Data Analysis, Statistics and Probability (physics.data-an)
Can An Uncertainty Relation Generate A Plasma?
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
A. Gholamhosseinian, R. W. Corkery, I. Brevik, Mathias Bostrom
We explore the fundamental idea that there may be a role for the Casimir effect, via an uncertainty relation, in the generation of electron-positron and quark-gluon plasmas. We investigate this concept, reviewing the possible contribution of semi-classical electrodynamics to nuclear interactions, specifically focusing on the Casimir effect at sub-Fermi length scales. The main result is a temperature distance relation, derived from the time-energy uncertainty relation, which can have observable consequences at these extreme scales. From a more general perspective, since the energy-time uncertainty relation appears to be a significant physical quantity, we also provide a brief overview of recent developments in this direction in Sec. 3.2.
Materials Science (cond-mat.mtrl-sci), High Energy Physics - Phenomenology (hep-ph)
Ferroelectric Properties and Topological Textures in PbTiO$_\mathrm{3}$ from a Second-Principles Open-Source interatomic potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Louis Bastogne, Philippe Ghosez
We introduce an open-source, fully atomistic second-principles interatomic potential for lead titanate (PbTiO3), a benchmark ferroelectric material known for its strong polarization and high temperature phase transitions. While density functional theory excels at capturing atomic-scale behavior, it remains computationally prohibitive for large-scale simulations required to explore complex phenomena. Our model addresses this limitation by accurately reproducing key properties of PbTiO3, including domain wall dynamics and skyrmion formation, which are known as key features to next-generation memory and energy-efficient technologies. Validated against DFT data, the model remains predictive across a wide range of conditions. It offers an accessible and efficient framework for high-accuracy large-scale simulations, allowing deeper insights into PbTiO3 and its potential applications.
Materials Science (cond-mat.mtrl-sci)
Giant Gate Response of the Charge in an Electron-Lattice Condensate
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Maedeh Taheri, Jordan Teeter, Topojit Debnath, Nicholas Sesing, Tina Salguero, Roger K. Lake, Alexander A. Balandin
Efficient electrical capacitive control is important for the next generation of ultra-low-power and ultra-fast electronics and energy-storage devices. Correlated electronic phases offer a powerful route to enhancing field-effect control beyond the limits of conventional capacitive gating. In such systems, modest gate voltages can couple to an order parameter, producing responses far larger than expected from the electrostatics of non-interacting carriers. It was demonstrated that electron-electron interactions, in which the exchange and correlation energies among electrons lower the chemical potential of an electron system as the electron density increases, can significantly increase the effective capacitance over its geometric capacitance value. Here, we show that the electron-lattice or electron-phonon correlations in charge density wave (CDW) condensate can lead to a giant gate response with the corresponding capacitance enhancement. This unusual phenomenon is demonstrated in the quasi-one-dimensional CDW material, where the gate-induced change in CDW charge density exceeds predictions based on geometrical gate capacitance by one to two orders of magnitude. This “giant gating” effect arises from the coupling of the electric field to the CDW electron-lattice condensate, demonstrating a mechanism for massively amplifying gate response via collective electronic behavior. We quantify the effect by determining the quantum capacitance of the CDW charge and by constructing a band diagram for the gated CDW device. The obtained results can lead to an alternative strategy for continuing the downscaling of the transistor feature size in electronic technology.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
25 pages; 9 figures
Role of Noise on Defect Formation and Correlations in a Long-Range Ising Model Under Adiabatic Driving
New Submission | Other Condensed Matter (cond-mat.other) | 2025-05-06 20:00 EDT
Santanu Dhara, Suhas Gangadharaiah
We study an exactly solvable long-range (LR) transverse-field Ising model (TFIM) with a power-law decaying interaction characterized by a decay exponent {\alpha}. In the thermodynamic limit, the system is adiabatically driven in the presence of noise, from a paramagnetic phase with all spins down to one with all spins up. Our study examines the role of long-range interactions on the defect density, its distribution, and spin correlations, comparing noisy and noiseless scenarios. In the noiseless case, within the long-range regime, the steady-state properties are primarily influenced by modes near the k = {\pi} region. However, in the presence of noise, the dominant contributions shift to the modes near k = 0. This differs from the SR model, where previous studies have shown that modes around k = {\pi}/2 play a significant role under noisy conditions. In the absence of noise, defect density scales as $ n\propto \tau_Q^{-1/2}$ , implying scaling exponent independent of decay exponent. However, we find that decreasing the value of {\alpha} (i.e., increasing the range) enhances the defect density, whereas in the presence of noise, it is suppressed. In the LR regime, two-point fermionic correlators initially exhibit Gaussian decay, followed by quadratic suppression instead of power-law decay for both noisy and noiseless scenarios. Meanwhile, spin correlators, expressed as a string of fermionic operators, undergo purely exponential decay with no crossover behavior. Furthermore, our analysis of defect formation reveals the influence of LR interaction on the kink-number distribution and its cumulants.
Other Condensed Matter (cond-mat.other)
14 pages, 15 figures
Escaping the Krylov space during finite precision Lanczos
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
J. Eckseler, M. Pieper, J. Schnack (Bielefeld University)
The Lanczos algorithm, introduced by Cornelius Lanczos, has been known for a long time and is widely used in computational physics. While often employed to approximate extreme eigenvalues and eigenvectores of an operator, recently interest in the sequence of basis vectors produced by the algorithm rose in the context of Krylov complexity. Although it is generally accepted and partially proven that the procedure is numerically stable for approximating the eigenvalues, there are numerical problems when investigating the Krylov basis constructed via the Lanczos procedure. In this paper, we show that loss of orthogonality and the attempt of reorthoganalization fall short of understanding and addressing the problem. Instead, the numerical sequence of eigenvectors in finite precision arithmetic escapes the true vector space spanned by the exact Lanczos vectors. This poses the real threat to an interpretation in view of the operator growth hypothesis.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
8 pages, 8 figures
Partons from stabilizer codes
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Rafael A. Macedo, Carlo C. Bellinati, Weslei B. Fontana, Eric C. Andrade, Rodrigo G. Pereira
The Gutzwiller projection of fermionic wave functions is a well-established method for generating variational wave functions describing exotic states of matter, such as quantum spin liquids. We investigate the conditions under which a projected wave function constructed from fermionic partons can be rigorously shown to possess topological order. We demonstrate that these conditions can be precisely determined in the case of projected Majorana stabilizer codes. We then use matrix product states to study states that interpolate between two distinct Majorana fermion codes, one yielding a $ \mathbb Z_2$ spin liquid and the other a trivial polarized state upon projection. While the free-fermion states are adiabatically connected, we find that the projected states undergo a phase transition detected by the topological entanglement entropy. Our work underscores the profound impact of the Gutzwiller projection and cautions against inferring properties of quantum spin liquids solely from their unprojected counterparts.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
10 pages, 8 figures
Magnetic Manipulation of Spatially Confined Multiferroic Heuslers by Martensitic Microstructure Engineering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Milad Takhsha, Vipin Kumar Singh, Julian Ledieu, Simone Fabbrici, Francesca Casoli, Francesco Mezzadri, Michal Horký, Vincent Fournée, Vojtěch Uhlíř, Franca Albertini
Magnetic shape-memory (MSM) Heuslers show a strong coupling between magnetic and structural characteristics, evidencing a correlation between magnetic, thermal, and mechanical properties through a magnetostructural martensitic transformation. This functional aspect makes MSM Heuslers promising for integration into smart micro/nanodevices, including sensors, energy harvesters, and actuators. Controlling the martensitic microstructure, which determines the magnetic characteristics, is among the key points for optimization of the magnetic functional properties of these materials at different length scales. Here, we report a strategy for manipulating the magnetic properties of spatially confined epitaxial Ni-Mn-Ga films grown on Cr(001)//MgO(001) by twinning configuration engineering in the low-temperature ferromagnetic (martensitic) phase. We show how the twinning configurations in the continuous films and the micropatterned structures can be switched from Y-type (showing negligible magnetic stray field) into X-type (presenting significant magnetic stray field) by a post-annealing process. Advanced characterization techniques enable us to analyze the atomic structure and the surface quality of the annealed samples and to disentangle the twin-switching phenomenon. The martensitic microstructure engineering reported in this study introduces a simple method for promoting the magnetic stray-field contribution at the surface of Ni-Mn-Ga epitaxial thin films and micropatterns initially showing a negligible magnetic stray field.
Materials Science (cond-mat.mtrl-sci)
Signatures of Kondo-lattice behavior in the two-dimensional ferromagnet Fe$_3$GeTe$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Carmen Rubio-Verdú, Katharina J. Franke
Fe$ _2$ GeTe$ _3$ is a paradigmatic van der Waals magnet with the full microscopic picture of magnetic interactions still under debate. Here, we use scanning tunneling microscopy and spectroscopy at 1.1 K to map out the low-energy physics on the surface. In agreement with previous works, we observe a spatially varying Fano lineshape that has been ascribed to a Kondo resonance. In addition, we identify a small gap of $ \approx$ 5 meV width on top of the larger-energy Fano resonance. We suggest that this gap is the signature of a coherent Kondo lattice that has been proposed to originate from hybridization of a strongly dispersing and a flat band both derived from $ d$ electrons of the Fe atoms in the lattice. Adding magnetic adatoms on the surface hardly influences the magnetic signatures of the substrate, indicating the robustness of the intralayer Kondo correlations against magnetic adsorbates.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Fermi surface nesting driven anomalous Hall effect in magnetically frustrated Mn_2PdIn
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-06 20:00 EDT
Afsar Ahmed, Arnab Bhattacharya, Prashant Singh, Ajay Kumar, Tukai Singha, Anis Biswas, Yaroslav Mudryk, Indranil Das
Noncollinear magnets with near-zero net magnetization and nontrivial bulk electronic topology hold significant promise for spintronic applications, though their scarcity necessitates purposeful design strategies. In this work, we report a topologically nontrivial electronic structure in metallic Mn_2PdIn, which crystallizes in the inverse Heusler structure and exhibits a spin-glassy ground state with quenched magnetization. The system features Weyl-type band crossings near the Fermi level and reveals a novel interplay among momentum-space nesting, orbital hybridization, and spin-orbit coupling. Comprehensive transport measurements uncover a pronounced anomalous Hall effect (AHE) in Mn_2PdIn. The observed quadratic relationship between the longitudinal and anomalous Hall resistivities highlights the intrinsic Berry curvature contribution to AHE. These findings establish inverse Heusler alloys as compelling platforms for realizing noncollinear magnets that host Weyl-type semimetallic or metallic phases-combining suppressed magnetization with robust electronic transport-thereby offering a promising route toward their seamless integration into next-generation spintronic devices.
Materials Science (cond-mat.mtrl-sci)
Non-Hermitian topology and skin modes in the continuum via parametric processes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-06 20:00 EDT
Markus Bestler, Alexander Dikopoltsev, Oded Zilberberg
We demonstrate that Hermitian, nonlocal parametric pairing processes can induce non-Hermitian topology and skin modes, offering a simple alternative to complex bath engineering. Our model, stabilized by local dissipation and operating in the continuum limit, reveals exceptional points that spawn a tilted diabolical line in the dispersion. Local dissipation prevents instabilities, while a bulk anomaly signals unscreened current response. Upon opening the boundaries, we observe a non-Hermitian skin effect with localized edge modes. Through bulk winding indices and non-Bloch theory, we establish a robust bulk-boundary correspondence, highlighting parametric drives as a scalable route to non-Hermitian topology in bosonic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
10 pages, 4 figures, and 2 appendices; comments are welcome
Particles, trajectories and diffusion: random walks in cooling granular gases
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
Santos Bravo Yuste, Rubén Gómez González, Vicente Garzó
We study the mean-square displacement (MSD) of a tracer particle diffusing in a granular gas of inelastic hard spheres under homogeneous cooling state (HCS). Tracer and granular gas particles are in general mechanically different. Our approach uses a series representation of the MSD where the $ k$ -th term is given in terms of the mean scalar product $ \langle \mathbf{r}_1\cdot\mathbf{r}_k \rangle$ , with $ \mathbf{r}_i$ denoting the displacements of the tracer between successive collisions. We find that this series approximates a geometric series with the ratio $ \Omega$ . We derive an explicit analytical expression of $ \Omega$ for granular gases in three dimensions, and validate it through a comparison with the numerical results obtained from the direct simulation Monte Carlo (DSMC) method. Our comparison covers a wide range of masses, sizes, and inelasticities. From the geometric series, we find that the MSD per collision is simply given by the mean-square free path of the particle divided by $ 1-\Omega$ . The analytical expression for the MSD derived here is compared with DSMC data and with the first- and second-Sonine approximations to the MSD obtained from the Chapman-Enskog solution of the Boltzmann equation. Surprisingly, despite their simplicity, our results outperforms the predictions of the first-Sonine approximation to the MSD, achieving accuracy comparable to the second-Sonine approximation.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
19 pages, 7 figures
Van-Hove singularities and competing instabilities in an altermagnetic metal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-06 20:00 EDT
Peng Rao, Johannes Knolle, Laura Classen
Van-Hove (VH) singularities in the single-particle band spectrum are important for interaction-driven quantum phases. Whereas VH points are usually spin-degenerate, in newly proposed altermagnets VH singularities can become spin-dependent, due to momentum-dependent spin polarization of the Fermi surfaces arising from combined rotation and time-reversal symmetry. We consider two altermagnetic models ($ d_{x^2-y^2}$ - and $ d_{xy}$ -wave) on a square lattice with spin-polarized VH points, and study their stable fixed-point solutions indicating interaction-induced instabilities using parquet renormalization group. In particular, for the $ d_{xy}$ -wave model, we find new stable fixed-point solutions of the renormalization group equations which are not connected to the solution in the spin-degenerate limit. This implies that on the square lattice, the system with VH singularities is unstable with respect to altermagnetic perturbations. The leading instability for the $ d_{x^2-y^2}$ -model is real transverse spin density wave. For the $ d_{xy}$ -wave model, it is found to be real transverse spin density wave at large altermagnetic splitting. At small altermagnetic splitting both imaginary charge density wave and real longitudinal spin density waves are dominant.
Strongly Correlated Electrons (cond-mat.str-el)
15 pages, 12 figures
Coexistence of Nodal and Nodeless Pairing Symmetry in Superconducting 6R-SnNbSe2
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-06 20:00 EDT
K. Yadav, M. Lamba, S. Patnaik
Majorana fermions, a fundamental idea to fault-tolerant quantum computing, can emerge in systems where superconductivity coexists with nontrivial band topology. One promising route to realizing such topological superconductors (TSCs) involves inducing superconductivity in topological materials, particularly in systems lacking inversion symmetry. In this study, we report the synthesis and detailed characterization of Sn-intercalated NbSe2, forming a new polytype, 6R-SnNbSe2. This compound crystallizes in the non-centrosymmetric space group R3m and exhibits bulk superconductivity below Tc around 4 K. Structural, electronic, and magnetic measurements confirm the emergence of a superconducting phase derived from Sn intercalation into the non-superconducting 3R-NbSe2. Temperature-dependent magnetic penetration depth and superfluid density measurements down to 1.5 K are performed using the tunnel diode oscillator technique. The findings suggest the mixing of nodal and nodeless superconductivity in 6R-SnNbSe2. Given the non-centrosymmetric nature of the crystal structure and the theoretical prediction of topological nodal-line features in SnNbSe2, it is an interesting candidate to investigate unconventional pairing mechanisms. Our findings highlight the potential of this material to host nontrivial superconducting states among the transition-metal dichalcogenides.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Strongly Correlated Electrons (cond-mat.str-el)
Statistical mechanical theory of liquid water
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-06 20:00 EDT
Water is an unusual liquid. Its thermophysical properties are non-monotonic with temperature T and pressure p. It’s not been known how water’s behaviors are encoded in its molecules. We give a statistical physics model, Cage Water, which assumes three bonding states: van der Waals, pairwise hydrogen bonding, and multi-body cooperative caging hydrogen bonds. The model is analytical, so very fast to compute, yet it gives excellent agreement with extensive pT experiments. Through readily interpretable substates, Cage Water explains water’s liquid anomalies – including its controversial liquid-liquid supercooling transition – as simple switchovers among the three bonding types.
Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Pauli crystal superradiance
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-06 20:00 EDT
Daniel Ortuño-Gonzalez, Rui Lin, Justyna Stefaniak, Alexander Baumgärtner, Gabriele Natale, Tobias Donner, R. Chitra
Pauli crystals are unique geometric structures of non-interacting fermions, resembling crystals, that emerge solely from Fermi statistics and confinement. Unlike genuine quantum crystals that arise from interparticle interactions, Pauli crystals do not break translation symmetry but nonetheless exhibit nontrivial many-body correlations. In this Letter, we explore Pauli crystal formation in a cavity-fermion setup. We analytically show that when coupled to a cavity, degeneracy in Pauli crystals can trigger zero-threshold transitions to superradiance. This superradiance is accompanied by the emergence of a genuine quantum crystalline state, wherein the atomic density is periodically modulated. We substantiate our findings using state-of-the-art numerical simulations. The combined interplay between statistics, confinement geometry and interactions mediated by light thus facilitates a novel pathway to quantum crystallization.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
7 pages, 3 figures