CMP Journal 2025-02-21
Statistics
Nature Materials: 2
Nature Nanotechnology: 2
Nature Physics: 2
Nature Reviews Physics: 1
Science: 5
Physical Review Letters: 10
Physical Review X: 1
arXiv: 60
Nature Materials
Origins of elasticity in molecular materials
Original Paper | Mechanical properties | 2025-02-20 19:00 EST
Amy J. Thompson, Bowie S. K. Chong, Elise P. Kenny, Jack D. Evans, Joshua A. Powell, Mark A. Spackman, John C. McMurtrie, Benjamin J. Powell, Jack K. Clegg
Elasticity is ubiquitous and produces a spontaneously reversible response to applied stress1. Despite the utility and importance of this property in regard to scientific and engineering applications, the atomic-scale location of the force that returns an object to its original shape remains elusive in molecular crystals. Here we use a series of density functional theory calculations to locate precisely where the energy is stored when single crystals of three molecular materials are placed under elastic stress. We show for each material that different intermolecular interactions are responsible for the restoring force under both expansive and compressive strain. These findings provide insight into the elastic behaviour of crystalline materials that is needed for more efficient design of flexible technologies and future smart devices.
Mechanical properties, Supramolecular chemistry
Graphene rolls with tunable chirality
Original Paper | Synthesis of graphene | 2025-02-20 19:00 EST
Enbing Zhang, Shuaishuai Ding, Xiaopeng Li, Xiangyun Ma, Xiaoqing Gao, Lei Liu, Yongtao Shen, Shiyu Cheng, Wenbo Mi, Yunlong Zhou, Guangyuan Feng, Yaru Song, Xiaojuan Li, Yunjia Xue, Kaiyao Xin, Xin Zeng, Qinyuan Jiang, Rufan Zhang, Xinfeng Liu, Zhongming Wei, Qingdao Zeng, Bin Wang, Qifeng Li, Ji Liu, Jing Yan, Shengbin Lei, Yanlian Yang, Wenping Hu
Creating chirality in achiral graphene and other two-dimensional materials has attracted broad scientific interest due to their potential application in advanced optics, electronics and spintronics. However, investigations into their optical activities and related chiro-electronic properties are constrained by experimental challenges, particularly in the precise control over the chirality of these materials. Here a universal wax-aided immersion method is developed to yield graphene rolls with controllable chiral angles, and the method can be generalized in other two-dimensional materials for high-yield fabrication. The left-handed and right-handed rolls exhibit optical activity and excellent spin selectivity effects with a spin polarization over 90% at room temperature. The discovery of tunable chirality-induced spin selectivity in tailored roll-shaped allotropes, achievable only through precise control of chirality, distinguishes itself from other carbon materials or existing chiral materials. Our Dirac fermion model shows that the electrons moving predominately along one side of the chiral roll develop a preferred spin polarization, and the rolling-chirality-induced spin selectivity is a result of this finite spin selectivity effect. Our method opens up opportunities for endowing achiral two-dimensional materials with tunable chirality, and may enable the emergence of quantum behaviours and room-temperature spintronic technologies.
Synthesis of graphene, Two-dimensional materials
Nature Nanotechnology
Systemic HER3 ligand-mimicking nanobioparticles enter the brain and reduce intracranial tumour growth
Original Paper | Drug delivery | 2025-02-20 19:00 EST
Felix Alonso-Valenteen, Simoun Mikhael, HongQiang Wang, Jessica Sims, Michael Taguiam, James Teh, Sam Sances, Michelle Wong, Tianxin Miao, Dustin Srinivas, Nelyda Gonzalez-Almeyda, Ryan H. Cho, Romny Sanchez, Kimngan Nguyenle, Erik Serrano, Briana Ondatje, Rebecca L. Benhaghnazar, Harry B. Gray, Zeev Gross, John Yu, Clive N. Svendsen, Ravinder Abrol, Lali K. Medina-Kauwe
Crossing the blood-brain barrier (BBB) and reaching intracranial tumours is a clinical challenge for current targeted interventions including antibody-based therapies, contributing to poor patient outcomes. Increased cell surface density of human epidermal growth factor receptor 3 (HER3) is associated with a growing number of metastatic tumour types and is observed on tumour cells that acquire resistance to a growing number of clinical targeted therapies. Here we describe the evaluation of HER3-homing nanobiological particles (nanobioparticles (NBPs)) on such tumours in preclinical models and our discovery that systemic NBPs could be found in the brain even in the absence of such tumours. Our subsequent studies described here show that HER3 is prominently associated with both mouse and human brain endothelium and with extravasation of systemic NBPs in mice and in human-derived BBB chips in contrast to non-targeted agents. In mice, systemically delivered NBPs carrying tumoricidal agents reduced the growth of intracranial triple-negative breast cancer cells, which also express HER3, with improved therapeutic profile compared to current therapies and compared to agents using traditional BBB transport routes. As HER3 associates with a growing number of metastatic tumours, the NBPs described here may offer targeted efficacy especially when such tumours localize to the brain.
Drug delivery, Nanoparticles
Intermediate-range solvent templating and counterion behaviour at charged carbon nanotube surfaces
Original Paper | Materials science | 2025-02-20 19:00 EST
Camilla Di Mino, Thomas F. Headen, Nadir S. Basma, David J. Buckley, Patrick L. Cullen, Martin C. Wilding, Milo S. P. Shaffer, Neal T. Skipper, Adam J. Clancy, Christopher A. Howard
The ordering of ions and solvent molecules around nanostructures is of profound fundamental importance, from understanding biological processes to the manipulation of nanomaterials to optimizing electrochemical devices. Classical models commonly used to describe these systems treat the solvent simplistically, an approach that endures, in part, due to the extreme difficulty of attaining experimental measurements that challenge this approximation. Here we perform total neutron scattering experiments on model systems--concentrated amide solutions of negatively charged carbon nanotubes and sodium counterions--and measure remarkably complex intermediate-range molecular solvent ordering. The charged surface orders the solvents up to ∼40 Å, even beyond its dense concentric solvation shells. Notably, the molecular orientation of solvent in direct contact with the nanotube surface itself is distinct, lying near-parallel and not interacting with desolvated sodium counterions. In contrast, beyond this layer the ordering of solvent is perpendicular to the surface. Our results underscore the critical importance of multibody interactions in solvated nanoscale systems and charged surfaces, highlighting competing ion/surface solvation effects.
Materials science, Nanoscience and technology
Nature Physics
Diffraction minima resolve point scatterers at few hundredths of the wavelength
Original Paper | Sub-wavelength optics | 2025-02-20 19:00 EST
Thomas A. Hensel, Jan O. Wirth, Ole L. Schwarz, Stefan W. Hell
Resolving two or more constantly scattering identical point sources using freely propagating waves is limited by diffraction. Here we show that, by illuminating with a diffraction minimum, a given number of point scatterers can be resolved at distances of small fractions of the wavelength. Specifically, we identify an 8 nm distance, which corresponds to 1/80 of the employed 640 nm wavelength, between two constantly emitting fluorescent molecules in the focal plane of an optical microscope. We also measure 22 nm side length for a quadratic array of four molecules. Moreover, we show that the measurement precision improves with decreasing distance and with increased scatterer density. This work opens up the prospect of resolving individual scatterers in clusters that are far smaller than the wavelength.
Sub-wavelength optics, Super-resolution microscopy
Cyclic jetting enables microbubble-mediated drug delivery
Original Paper | Biophysics | 2025-02-20 19:00 EST
Marco Cattaneo, Giulia Guerriero, Gazendra Shakya, Lisa A. Krattiger, Lorenza G. Paganella, Maria L. Narciso, Outi Supponen
The pursuit of targeted therapies capable of overcoming biological barriers, including the blood-brain barrier, has spurred the investigation of stimuli-responsive microagents that can improve therapeutic efficacy and reduce undesirable side effects. Intravenously administered, ultrasound-responsive microbubbles are promising agents with demonstrated potential in clinical trials, but the mechanism underlying drug absorption remains unclear. Here we show that ultrasound-driven single microbubbles puncture the cell membrane and induce drug uptake through stable cyclic microjets. Our theoretical models successfully reproduce the observed bubble and cell dynamic responses. We find that cyclic jets arise from shape instabilities, as opposed to classical inertial jets that are driven by pressure gradients, enabling microjet formation at mild ultrasound pressures below 100 kPa. We also establish a threshold for bubble radial expansion beyond which microjets form and facilitate cellular permeation and show that the stress generated by microjetting outperforms previously suggested mechanisms by at least an order of magnitude. Overall, this work elucidates the physics behind microbubble-mediated targeted drug delivery and provides the criteria for its effective and safe application.
Biophysics, Fluid dynamics
Nature Reviews Physics
Mechanisms of insect respiration
Review Paper | Biological physics | 2025-02-20 19:00 EST
Saadbin Khan, Anne E. Staples
Insect respiration is characterized by the rapid transport of respiratory gases within the organism and efficient exchange with the external environment. The unique respiratory system of insects comprises a network of tracheal tubes that directly supply oxygen to the cells throughout the body of an insect, eliminating the need for blood as an intermediate oxygen carrier. The remarkable diversity of insects and their exceptionally high aerobic scope, possibly the highest in the animal kingdom, demonstrate the success of their respiratory strategy. Microfluidic technology, particularly in the domain of gas microfluidics, also stands to benefit from emulating the mechanical proficiency demonstrated by insects in manipulating fluids at the microscale. Despite this significance, current understanding of the fundamental principles underlying insect respiration is incomplete. This Review presents an overview of insect respiratory physics and identifies promising areas for future investigations.
Biological physics, Computational biophysics
Science
Disease diagnostics using machine learning of B cell and T cell receptor sequences
Research Article | Immunology | 2025-02-21 03:00 EST
Maxim E. Zaslavsky, Erin Craig, Jackson K. Michuda, Nidhi Sehgal, Nikhil Ram-Mohan, Ji-Yeun Lee, Khoa D. Nguyen, Ramona A. Hoh, Tho D. Pham, Katharina Röltgen, Brandon Lam, Ella S. Parsons, Susan R. Macwana, Wade DeJager, Elizabeth M. Drapeau, Krishna M. Roskin, Charlotte Cunningham-Rundles, M. Anthony Moody, Barton F. Haynes, Jason D. Goldman, James R. Heath, R. Sharon Chinthrajah, Kari C. Nadeau, Benjamin A. Pinsky, Catherine A. Blish, Scott E. Hensley, Kent Jensen, Everett Meyer, Imelda Balboni, Paul J. Utz, Joan T. Merrill, Joel M. Guthridge, Judith A. James, Samuel Yang, Robert Tibshirani, Anshul Kundaje, Scott D. Boyd
Clinical diagnosis typically incorporates physical examination, patient history, various laboratory tests, and imaging studies but makes limited use of the human immune system's own record of antigen exposures encoded by receptors on B cells and T cells. We analyzed immune receptor datasets from 593 individuals to develop MAchine Learning for Immunological Diagnosis, an interpretive framework to screen for multiple illnesses simultaneously or precisely test for one condition. This approach detects specific infections, autoimmune disorders, vaccine responses, and disease severity differences. Human-interpretable features of the model recapitulate known immune responses to severe acute respiratory syndrome coronavirus 2, influenza, and human immunodeficiency virus, highlight antigen-specific receptors, and reveal distinct characteristics of systemic lupus erythematosus and type-1 diabetes autoreactivity. This analysis framework has broad potential for scientific and clinical interpretation of immune responses.
Reviving-like prosocial behavior in response to unconscious or dead conspecifics in rodents
Research Article | Neuroscience | 2025-02-21 03:00 EST
Wenjian Sun, Guang-Wei Zhang, Junxiang J. Huang, Can Tao, Michelle B. Seo, Huizhong Whit Tao, Li I. Zhang
Whereas humans exhibit emergency responses to assist unconscious individuals, how nonhuman animals react to unresponsive conspecifics is less well understood. We report that mice exhibit stereotypic behaviors toward unconscious or dead social partners, which escalate from sniffing and grooming to more forceful actions such as mouth or tongue biting and tongue pulling. The latter intense actions, more prominent in familiar pairs, begin after prolonged immobility and unresponsiveness and cease when the partner regains activity. Their consequences, including improved airway opening and clearance and accelerated recovery from unconsciousness, suggest rescue-like efforts. Oxytocin neurons in the hypothalamic paraventricular nucleus respond differentially to the presence of unconscious versus active partners, and their activation, along with oxytocin signaling, is required for the reviving-like actions. This tendency to assist unresponsive members may enhance group cohesion and survival of social species.
A neural basis for prosocial behavior toward unresponsive individuals
Research Article | Neuroscience | 2025-02-21 03:00 EST
Fangmiao Sun, Ye Emily Wu, Weizhe Hong
Humans often take actions to assist others experiencing unresponsiveness, such as transient loss of consciousness. How other animals react to unresponsive conspecifics--and the neural mechanisms driving such behaviors--remain largely unexplored. In this study, we demonstrated that mice exhibit rescue-like social behaviors toward unresponsive conspecifics, characterized by intense physical contact and grooming directed at the recipient's facial and mouth areas, which expedite their recovery from unresponsiveness. We identified the medial amygdala (MeA) as a key region that encodes the unresponsive state of others and drives this head-directed physical contact. Notably, the behavioral responses toward unresponsive conspecifics differed from those directed at awake, stressed individuals, and these responses were differentially represented in the MeA. These findings shed light on the neural mechanisms underlying prosocial responses toward unresponsive individuals.
Antiviral signaling of a type III CRISPR-associated deaminase
Research Article | Crispr | 2025-02-21 03:00 EST
Yutao Li, Zhaoxing Li, Purui Yan, Chenyang Hua, Jianping Kong, Wanqian Wu, Yurong Cui, Yan Duan, Shunxiang Li, Guanglei Li, Shunli Ji, Yijun Chen, Yucheng Zhao, Peng Yang, Chunyi Hu, Meiling Lu, Meirong Chen, Yibei Xiao
Prokaryotes have evolved diverse defense strategies against viral infection, including foreign nucleic acid degradation by CRISPR-Cas systems and DNA and RNA synthesis inhibition through nucleotide pool depletion. Here, we report an antiviral mechanism of type III CRISPR-Cas-regulated adenosine triphosphate (ATP) depletion in which ATP is converted into inosine triphosphate (ITP) by CRISPR-Cas-associated adenosine deaminase (CAAD) upon activation by either cA4 or cA6, followed by hydrolysis into inosine monophosphate (IMP) by Nudix hydrolase, ultimately resulting in cell growth arrest. The cryo-electron microscopy structures of CAAD in its apo and activated forms, together with biochemical evidence, revealed how cA4 or cA6 binds to the CRISPR-associated Rossmann fold (CARF) domain and abrogates CAAD autoinhibition, inducing substantial conformational changes that reshape the structure of CAAD and induce its deaminase activity. Our results reveal the mechanism of a CRISPR-Cas-regulated ATP depletion antiviral strategy.
Experimental evolution of evolvability
Research Article | Evolution | 2025-02-21 03:00 EST
Michael Barnett, Lena Meister, Paul B. Rainey
Evolvability--the capacity to generate adaptive variation--is a trait that can itself evolve through natural selection. However, the idea that mutation can become biased toward adaptive outcomes remains controversial. In this work, we report the evolution of enhanced evolvability through localized hypermutation in experimental populations of bacteria. The evolved mechanism is analogous to the mutation-prone sequences of contingency loci observed in pathogenic bacteria. Central to this outcome was a lineage-level selection process, where success depended on the capacity to evolve between two phenotypic states. Subsequent evolution showed that the hypermutable locus is itself evolvable with respect to alterations in the frequency of environmental change. Lineages with localized hypermutability were more likely to acquire additional adaptive mutations, revealing an unanticipated benefit.
Physical Review Letters
Experimental Quantum Advantage in the Odd-Cycle Game
Research article | Nonlocality | 2025-02-21 05:00 EST
P. Drmota, D. Main, E. M. Ainley, A. Agrawal, G. Araneda, D. P. Nadlinger, B. C. Nichol, R. Srinivas, A. Cabello, and D. M. Lucas
A two-player team that shares a pair of entangled particles can outplay a team that uses only classical strategies.
Phys. Rev. Lett. 134, 070201 (2025)
Nonlocality, Quantum entanglement, Quantum networks, Trapped ions
Stability of Mixed-State Quantum Phases via Finite Markov Length
Research article | Open quantum systems & decoherence | 2025-02-21 05:00 EST
Shengqi Sang and Timothy H. Hsieh
For quantum phases of Hamiltonian ground states, the energy gap plays a central role in ensuring the stability of the phase as long as the gap remains finite. We propose Markov length, the length scale at which the quantum conditional mutual information (CMI) decays exponentially, as an equally essential quantity characterizing mixed-state phases and transitions. For a state evolving under a local Lindbladian, we argue that if its Markov length remains finite along the evolution, then it remains in the same phase, meaning there exists another quasilocal Lindbladian evolution that can reverse the former one. We apply this diagnostic to toric code subject to decoherence and show that the Markov length is finite everywhere except at its decodability transition, at which it diverges. CMI in this case can be mapped to the free energy cost of point defects in the random bond Ising model. This implies that the mixed-state phase transition coincides with the decodability transition and also suggests a quasilocal decoding channel.
Phys. Rev. Lett. 134, 070403 (2025)
Open quantum systems & decoherence, Quantum error correction, Quantum phase transitions, Topological phases of matter
Minimum Neutron Star Mass in Neutrino-Driven Supernova Explosions
Research article | Novae & supernovae | 2025-02-21 05:00 EST
Bernhard Müller, Alexander Heger, and Jade Powell
A realistic 3D supernova simulation shows that neutron stars with masses as low as 1.192 solar masses are possible, resolving the tension between observed low mass neutron stars and theory's inability to account for them.
Phys. Rev. Lett. 134, 071403 (2025)
Novae & supernovae, Binary stars, Neutron stars & pulsars, Astronomical masses & mass distributions, Numerical simulations in gravitation & astrophysics
Photon Many-Body Dispersion: Exchange-Correlation Functional for Strongly Coupled Light-Matter Systems
Research article | Density functional theory | 2025-02-21 05:00 EST
Cankut Tasci, Leonardo A. Cunha, and Johannes Flick
We introduce an electron-photon exchange-correlation functional for quantum electrodynamical density-functional theory (QEDFT). The approach, photon MBD (pMBD), is inspired by the many-body dispersion (MBD) method for weak intermolecular interactions, which is generalized to include both electronic and photonic (electromagnetic) degrees of freedom on the same footing. We demonstrate that pMBD accurately captures effects that arise in the context of strong light-matter interactions, such as anisotropic electron-photon interactions, beyond single-photon effects, and cavity-modulated van der Waals interactions. Moreover, we show that pMBD is computationally efficient and allows simulations of large complex systems coupled to optical cavities.
Phys. Rev. Lett. 134, 073002 (2025)
Density functional theory, Electronic structure, Electronic structure of atoms & molecules, First-principles calculations, Interatomic & molecular potentials, Light-matter interaction
Non-Gaussian Generalized Two-Mode Squeezing: Applications to Two-Ensemble Spin Squeezing and Beyond
Research article | Cavity quantum electrodynamics | 2025-02-21 05:00 EST
Mikhail Mamaev, Martin Koppenhöfer, Andrew Pocklington, and Aashish A. Clerk
Bosonic two-mode squeezed states are paradigmatic entangled Gaussian states that have wide utility in quantum information and metrology. Here, we show that the basic structure of these states can be generalized to arbitrary bipartite quantum systems in a manner that allows simultaneous, Heisenberg-limited estimation of two independent parameters for finite-dimensional systems. Further, we show that these general states can always be stabilized by a relatively simple Markovian dissipative process. In the specific case where the two subsystems are ensembles of two-level atoms or spins, our generalized states define a notion of two-mode spin squeezing that is valid beyond the Gaussian limit and that enables true multiparameter estimation. We discuss how generalized Ramsey measurements allow one to reach the two-parameter quantum Cram'er-Rao bound, and how the dissipative preparation scheme is compatible with current experiments.
Phys. Rev. Lett. 134, 073603 (2025)
Cavity quantum electrodynamics, Quantum Fisher information, Quantum metrology, Quantum parameter estimation, Squeezing of quantum noise
Controlling the Dynamics of Atomic Correlations via the Coupling to a Dissipative Cavity
Research article | Cavity quantum electrodynamics | 2025-02-21 05:00 EST
Catalin-Mihai Halati, Ameneh Sheikhan, Giovanna Morigi, and Corinna Kollath
We analyze the relaxation dynamics in an open system, composed by a quantum gas of bosons in a lattice interacting via both contact and global interactions. We report the onset of periodic oscillations of the atomic coherences exhibiting hallmarks of synchronization after a quantum quench. The dynamical behavior exhibits the many-body collapse and revival of atomic coherences and emerges from the interplay of the quantum dissipative nature of the cavity field and the presence of a (approximate) strong symmetry in the dissipative system. We further show that the approximate symmetry can dynamically self-organize. We argue that the approximate symmetry can be tailored to obtain long-lived coherences. These insights provide a general recipe to engineer the dynamics of globally interacting systems.
Phys. Rev. Lett. 134, 073604 (2025)
Cavity quantum electrodynamics, Dissipative dynamics, Open quantum systems & decoherence, Quantum cavities, Bose-Hubbard model, Matrix product states
Effective Transport by 2D Turbulence: Vortex-Gas Theory vs Scale-Invariant Inverse Cascade
Research article | Energy cascade | 2025-02-21 05:00 EST
Julie Meunier and Basile Gallet
The scale-invariant inverse energy cascade is a hallmark of 2D turbulence, with its theoretical energy spectrum observed in both direct numerical simulations (DNS) and laboratory experiments. Under this scale-invariance assumption, the effective diffusivity of a 2D turbulent flow is dimensionally controlled by the energy flux and the friction coefficient only. Surprisingly, however, we show that such scaling predictions are invalidated by numerical solutions of the 2D Navier-Stokes equation forced at intermediate wave number and damped by weak linear or quadratic drag. We derive alternate scaling-laws for the effective diffusivity based on the emergence of intense, isolated vortices causing spatially inhomogeneous frictional dissipation localized within the small vortex cores. The predictions quantitatively match DNS data. This study points to a universal large-scale organization of 2D turbulent flows in physical space, bridging standard 2D Navier-Stokes turbulence with large-scale geophysical turbulence.
Phys. Rev. Lett. 134, 074101 (2025)
Energy cascade, Intermittency, Mixing in geophysical flows, Turbulence, Turbulent mixing, Vortex dynamics
X-Ray Signature of the Superionic Transition in Warm Dense fcc Water Ice
Research article | Phase transitions | 2025-02-21 05:00 EST
Alexis Forestier, Gunnar Weck, Frédéric Datchi, Sandra Ninet, Gaston Garbarino, Mohamed Mezouar, and Paul Loubeyre
The fcc superionic phase of ice is a key component of the warm dense water phase diagram. While a few x-ray diffraction studies, under dynamic and static compressions, have reported the stability of the fcc structure, the transition to the superionic state has not been investigated in detail. Here, a remarkable thermal volume expansion is disclosed, which is interpreted as being directly related to the superionic transition. This could be achieved by implementing a heating capsule geometry within the laser-heated diamond anvil cell. Fcc ice is recovered metastable at ambient temperature, allowing us to observe that superionicity in the fcc phase emerges at a slightly lower temperature than for the bcc--fcc structural transition. The crossover in volume thermal expansion at the superionic transition agrees with recent ab initio calculations; however, its magnitude is larger than predicted.
Phys. Rev. Lett. 134, 076102 (2025)
Phase transitions, Pressure effects, Ice, X-ray diffraction
Feshbach Resonances in Exciton--Charge-Carrier Scattering in Semiconductor Bilayers
Research article | Excitons | 2025-02-21 05:00 EST
Marcel Wagner, Rafał Ołdziejewski, Félix Rose, Verena Köder, Clemens Kuhlenkamp, Ataç İmamoğlu, and Richard Schmidt
Feshbach resonances play a vital role in the success of cold atoms investigating strongly correlated physics. The recent observation of their solid-state analog in the scattering of holes and intralayer excitons in transition metal dichalcogenides [I. Schwartz et al., Science 374, 336 (2021)] holds compelling promise for bringing fully controllable interactions to the field of semiconductors. Here, we demonstrate how tunneling-induced layer hybridization can lead to the emergence of two distinct classes of Feshbach resonances in atomically thin semiconductors. Based on microscopic scattering theory we show that these two types of Feshbach resonances allow us to tune interactions between electrons and both short-lived intralayer, as well as long-lived interlayer excitons. We predict the exciton-electron scattering phase shift from first principles and show that the exciton-electron coupling is fully tunable from strong to vanishing interactions. The tunability of interactions opens the avenue to explore Bose-Fermi mixtures in solid-state systems in regimes that were previously only accessible in cold atom experiments.
Phys. Rev. Lett. 134, 076903 (2025)
Excitons, Scattering theory, Transition metal dichalcogenides, Ultracold gases, Feshbach resonance, Optical absorption spectroscopy
Attraction-Enhanced Emergence of Friction in Colloidal Matter
Research article | Friction | 2025-02-21 05:00 EST
Berend van der Meer, Taiki Yanagishima, and Roel P. A. Dullens
How frictional effects emerge at the microscopic level in particulate materials remains a challenging question, particularly in systems subject to thermal fluctuations due to the transient nature of interparticle contacts. Here, we directly relate particle-level frictional arrest to local coordination in an attractive colloidal model system. We reveal that the orientational dynamics of particles slows down exponentially with increasing coordination number due to the emergence of frictional interactions, the strength of which can be tuned simply by varying the attraction strength. Using a simple computer simulation model, we uncover how the interparticle interactions govern the formation of frictional contacts between particles. Our results establish quantitative relations between friction, coordination, and interparticle interactions. This is a key step toward using interparticle friction to tune the mechanical properties of particulate materials.
Phys. Rev. Lett. 134, 078202 (2025)
Friction, Colloidal gel, Colloids
Physical Review X
Superballistic Conduction in Hydrodynamic Antidot Graphene Superlattices
Research article | Ballistic transport | 2025-02-21 05:00 EST
Jorge Estrada-Álvarez, Juan Salvador-Sánchez, Ana Pérez-Rodríguez, Carlos Sánchez-Sánchez, Vito Clericò, Daniel Vaquero, Kenji Watanabe, Takashi Taniguchi, Enrique Diez, Francisco Domínguez-Adame, Mario Amado, and Elena Díaz
An array of holes in a 2D material enhances an effect that improves the flow of electric currents.
Phys. Rev. X 15, 011039 (2025)
Ballistic transport, Classical transport, Electrical properties, Mesoscopics, Graphene, Hexagonal boron nitride, Nanostructures, Two-dimensional electron gas, Boltzmann theory, Finite-element method, Hydrodynamic models, Resistivity measurements
arXiv
Dumbbell Fermions and Spin Models on Honeycomb Lattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
We express Kitaev's exact solution of spin models on the honeycomb lattice as a special case of a higher dimensional duality between staggered Majorana fermions and Pauli spins. General models with bilinear nearest neighbor couplings of spins and external magnetic fields are soluble in this way. Each model gives rise to an infinite number of single particle fermion Schrodinger equations, depending on the choice of discrete gauge field flux.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th)
4 Pages, LaTeX2e
Purely Electronic Chirality without Structural Chirality
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Takayuki Ishitobi, Kazumasa Hattori
We introduce the concept of purely electronic chirality, which arises in the absence of structural chirality. In condensed matter physics and chemistry, chirality has conventionally been understood as a mirror-image asymmetry in crystal or molecular structures. We demonstrate that certain electronic orders exhibit chirality-related properties without atomic displacement. Specifically, we investigate quadrupole orders to realize such purely electronic chirality with handedness that can be tuned by magnetic fields. As a representative example, we analyze a model featuring \(120^\circ\) antiferro quadrupole orders on a distorted kagomé lattice, predicting various chirality-related responses in the nonmagnetic ordered phase of URhSn. Furthermore, as a phonon analog, chiral phonons can emerge in achiral crystals through coupling with the pEC order. Our results provide a distinct origin of chirality and a fundamental basis for exploring the interplay between electronic and structural chirality.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
4 pages 2 figures
Landau Theory of Dynamic Critical Phenomena in the Rayleigh-Benard System
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-21 20:00 EST
Physics involving more details than hydrodynamics is needed to formulate rate thermodynamics of the Rayleigh-Bénard system. The Boussinesq vector field is approached in the space of mesoscopic vector fields similarly as equilibrium sates are approached in externally unforced systems in the space of mesoscopic state variables. The approach is driven by gradient of a potential (called a rate entropy). This potential then provides the rate thermodynamics in the same way as the entropy provides thermodynamics for externally unforced systems. By restricting the investigation to a small neighborhood of the critical point we can use the rate-thermodynamic version of the Landau theory.
Statistical Mechanics (cond-mat.stat-mech)
16 pages, no figure
Orbital Wigner functions and quantum transport in multiband systems
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-21 20:00 EST
Johannes Mitscherling, Dan S. Borgnia, SuryaNeil Ahuja, Joel E. Moore, Vir B. Bulchandani
Traditional theories of electron transport in crystals are based on the Boltzmann equation and do not capture physics arising from quantum coherence. We introduce a transport formalism based on ''orbital Wigner functions'', which accurately captures quantum coherent physics in multiband fermionic systems. We illustrate the power of this approach compared to traditional semiclassical transport theory by testing it numerically against microscopic simulations of one-dimensional, non-interacting, two-band systems -- the simplest systems capable of exhibiting inter-orbital coherence. We show that orbital Wigner functions accurately capture strongly non-equilibrium features of electron dynamics that lie beyond conventional Boltzmann theory, such as the ballistic transport of a relative phase between microscopic orbitals and topological Thouless pumping of charge both at non-zero temperature and away from the adiabatic limit. Our approach is motivated in part by modern ultracold atom experiments that can prepare and measure far-from-equilibrium charge transport and phase coherence in multiband fermionic systems, calling for correspondingly precise theories of transport. The quantitative accuracy exhibited by our approach, together with its capacity to capture nontrivial physics even at the ballistic scale, establishes orbital Wigner functions as an ideal starting point for developing a fully systematic theory of transport in crystals.
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
17+4 pages, 6 figures. Any comments are welcome!
Critical theories connecting gapped phases with \(\mathbb{Z}_2\times\mathbb{Z}_2\) symmetry from the duality web
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Andreas Karch, Ryan C. Spieler
We use the ideas behind the duality web to construct numerous conformal field theories mediating the phase transitions between various symmetry broken and topological phases. In particular we obtain the full field theory version of the Kennedy Tasaki transformation, mapping a gapless theory mediating a topological phase transition of symmetry protected topological orders to a standard symmetry breaking one in a 1+1 dimensional \(\mathbb{Z}_2 \times \mathbb{Z}_2\) gauge theory. When we consider all possible discrete gauging operations, we obtain bosonic and fermionic webs with 9 critical theories per web, each connecting 4 separate gapped phases, some of them topological. Bosonization maps the two webs into each other. In addition to discussing the multi-critical theory connecting the four gapped phases in each phase diagram, we discuss the partially gapped theories connecting two of those four. Some of these are gapless symmetry protected topological phases.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
36 pages, 3 tables, 4 figures, 18 phase diagrams. Comments welcome
Elastic Quantum Criticality in Nematics and Altermagnets via the Elasto-Caloric Effect
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Charles R. W. Steward, Grgur Palle, Markus Garst, Joerg Schmalian, Iksu Jang
The coupling between electronic nematic degrees of freedom and acoustic phonons is known to significantly alter the universality class of a nematic quantum critical point (QCP). While non-Fermi-liquid behaviour emerges in the absence of lattice coupling, the inclusion of interactions with acoustic phonons results in observables such as heat capacity and single-particle scattering rate exhibiting only subleading non-analytic corrections to dominant Fermi-liquid terms. In this work, we demonstrate that the elastocaloric effect (ECE) -- the adiabatic temperature change under varying strain -- and the thermal expansion deviate from this pattern. Despite lattice coupling weakening the singularity of the ECE, it preserves a dominant non-Fermi-liquid temperature dependence. By drawing analogies between nematic systems and field-tuned altermagnets, we further show that similar responses are expected for the ECE near altermagnetic QCPs. We classify the types of piezomagnetic couplings and analyse the regimes arising from field-tuned magnetoelastic interactions. Our findings are shown to be consistent with the scaling theory for elastic quantum criticality and they further emphasize the suitability of the ECE as a sensitive probe near QCPs.
Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 9 figures
Dynamical Confinement and Magnetic Traps for Charges and Spins
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Afshin Besharat, Alexander A. Penin
We use the effective field theory approach to systematically study the dynamics of classical and quantum systems in an oscillating magnetic field. We find that the fast field oscillations give rise to an effective interaction which is able to confine charged particles as well as neutral particles with a spin magnetic moment. The effect is reminiscent of the renown dynamical stabilization of charges by the oscillating electric field and provides a foundation for a new class of magnetic traps. The properties characteristic to the dynamical magnetic confinement are reviewed.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th)
5 pages
Projected and Solvable Topological Heavy Fermion Model of Twisted Bilayer Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Haoyu Hu, Zhi-Da Song, B. Andrei Bernevig
We investigate the topological heavy-fermion (THF) model of magic-angle twisted bilayer graphene (MATBG) in the projected limit, where only the flat bands are present in the low-energy spectrum. Such limit has been previously analyzed in momentum-space Bistritzer-MacDonald-type continuum models, but not in a real-space formalism. In this regime, the Hubbard interaction (\(U_1\)) of the \(f\)-electrons is larger than the bandwidth (\(2M\)) of the flat bands but smaller than the gap (\(\gamma\)) between the flat and remote bands. In the THF model, concentrated charge (in real space) and concentrated Berry curvature (in momentum space) are respectively realized by exponentially localized \(f\)-orbitals and itinerant Dirac \(c\)-electrons. Local moments naturally arise from \(f\)-orbitals. Hybridizing the \(f\)-electrons with \(c\)-electrons produces power-law tails of the flat-band Wannier functions, raising the question of relevance of the local moment picture in the projected \(U_1\ll \gamma\) limit. Nonetheless, we find that the local moments remain stable as long as \(U_1 \gg \Delta(\omega)\) for \(|\omega|\lesssim U_1\), where \(\Delta(\omega)\sim \gamma^2 N(\omega)\) is the hybridization function seen by each \(f\)-site, and \(N(\omega)\) is the density of states of the Dirac \(c\)-bands. Notably, the comparison between \(U_1\) and \(\gamma\) is irrelevant to the local moment formation if \(N(\omega)\) is unknown. Within the framework of THF, we also derive the correlated self-energy of the flat bands using the Hubbard-I approximation and estimate the coupling strength between the local moments. Finally, we comment that, in the regime of extremely concentrated Berry curvature, the single-particle gap between flat bands and remote bands vanishes and the interaction is always larger than the gap.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
28 pages, 2 figures
Towards a global phase diagram of Ce-based dipolar-octupolar pyrochlore magnets under magnetic fields
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Recent experiments have established a strong case for Ce\(_2\)(Zr, Sn, Hf)\(_2\)O\(_7\) to host \(\pi\)-flux quantum spin ice (QSI). However, an irrefutable conclusion still requires strong, multifaceted evidence. In dipolar-octupolar (DO) compounds, external magnetic fields only strongly couple with the dipolar component \(\tau_z\) along its local z-axis in contrast to octupolar components \(\tau^{x,y}\). This gives rise to the unique ways magnetic fields interact with the system and, in turn, provides us with a variety of tuning knobs to generate comprehensive experimental results. In this work, we focus on magnetic fields along the (110), (111), and (001) directions and present a plethora of remarkable experimental signatures to probe the underlying physics of \(\pi\)-flux QSI using gauge mean field theory (GMFT) and Monte Carlo simulations. In particular, we present unique signatures in magnetic field-dependent phase diagrams, equal-time and dynamical structure factors, and magnetostriction.
Strongly Correlated Electrons (cond-mat.str-el)
Main text: 7 pages, 4 figures; Supplemental material: 14 pages, 7 figures
High-dimensional random landscapes: from typical to large deviations
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-21 20:00 EST
In these notes we discuss tools and concepts that emerge when studying high-dimensional random landscapes, i.e., random functions on high-dimensional spaces. As an example, we consider a high-dimensional inference problem in two forms: matrix denoising (Case 1) and tensor denoising (Case 2). We show how to map the inference problem onto the optimization problem of a high-dimensional landscape, which exhibits distinct geometrical properties in the two Cases. We discuss methods for characterizing typical realizations of these landscapes and their optimization through local dynamics. We conclude by highlighting connections between the landscape problem and Large Deviation Theory.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistics Theory (math.ST)
Notes for a course at the Les Houches school "Theory of Large Deviations and Applications". Comments are welcome
Enhancement of Superconductivity in WP via Oxide-Assisted Chemical Vapor Transport
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Daniel J. Campbell, Wen-Chen Lin, John Collini, Yun Suk Eo, Yash Anand, Shanta Saha, Dave Graf, Peter Y. Zavalij, Johnpierre Paglione
Tungsten monophosphide (WP) has been reported to superconduct below 0.8 K, and theoretical work has predicted an unconventional Cooper pairing mechanism. Here we present data for WP single crystals grown by means of chemical vapor transport (CVT) of WO3, P, and I2. In comparison to synthesis using WP powder as a starting material, this technique results in samples with substantially decreased low-temperature scattering and favors a more three dimensional morphology. We also find that the resistive superconducting transitions in these samples begin above 1 K. Variation in Tc is often found in strongly correlated superconductors, and its presence in WP could be the result of influence from a competing order and/or a non s-wave gap.
Superconductivity (cond-mat.supr-con)
8 pages, 5 figures
The origin and scarcity of breathing pyrochlore lattices in spinel oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Valentina Mazzotti, Solveig S. Aamlid, Abraham A. Mancilla, Janna Machts, Megan Rutherford, Jörg Rottler, Kenji M. Kojima, Alannah M. Hallas
Breathing pyrochlores are a unique class of materials characterized by a three-dimensional lattice of corner-sharing tetrahedra. However, unlike conventional pyrochlores where all tetrahedra are identical in size, the breathing pyrochlore lattice is composed of alternating large and small tetrahedra. Experimental realizations of the breathing pyrochlore lattice are rare but they do occur in \(A\)-site ordered spinels, as in the prototype materials LiGaCr\(_4\)O\(_8\) and LiInCr\(_4\)O\(_8\). In this work, we demonstrate that Cr cannot be straightforwardly substituted with other magnetic transition metals while retaining the breathing pyrochlore structure. To explain this observation, we perform density functional theory (DFT) calculations to investigate the formation and stability of LiGaCr\(_4\)O\(_8\) and LiInCr\(_4\)O\(_8\), focusing on the energy scales associated with \(A\) and \(B\)-site orderings as well as the magnetic exchange interactions of Cr ions. We identify the strong octahedral site preference of Cr\(^{3+}\) as a key factor in protecting the structural integrity of the pyrochlore sublattice, which in turn enables the breathing distortion to proceed. We also demonstrate that the charge order between the \(A\) (Li) and \(A'\) sites (Ga or In) is maintained at all temperatures up to decomposition. Furthermore, while the magnetic exchange interactions constitute a relatively small energy scale and therefore do not play a fundamental role in the structural stability of LiGaCr\(_4\)O\(_8\) and LiInCr\(_4\)O\(_8\), magnetism may play a critical role in setting the magnitude of the tetrahedral distortion. Ultimately, we conclude that the scarcity of breathing pyrochlores is a consequence of the stringent requirement on site ordering for their formation.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Accepted in Phys. Rev. Materials
Quantum spin liquid phase in the Shastry-Sutherland model revealed by high-precision infinite projected entangled-pair states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Philippe Corboz, Yining Zhang, Boris Ponsioen, Frédéric Mila
The Shastry-Sutherland model is an effective model of the layered material SrCu\(_2\)(BO\(_3\))\(_2\), which exhibits an extremely rich phase diagram as a function of pressure and magnetic field. Motivated by the recent controversy regarding its phase diagram at zero magnetic field, we perform large-scale simulations based on infinite projected entangled-pair states (iPEPS), a two-dimensional tensor network ansatz to represent the ground state directly in the thermodynamic limit. By employing the latest optimization techniques, we obtain variational states with lower energy than previous results obtained from other methods. Using systematic extrapolations to the exact infinite bond dimension limit, our simulations reveal a narrow quantum spin liquid phase between the plaquette and antiferromagnetic phases in the range \(0.785(5) \le J'/J \le 0.82(1)\).
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 6 figures
Moiré-Tunable Localization of Simultaneous Type I and Type II Band Alignment in a MoSe2/WS2 Heterobilayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Jiaxuan Guo, Zachary H. Withers, Ziling Li, Bowen Hou, Alexander Adler, Jianwei Ding, Victor Chang Lee, Roland K. Kawakami, Gerd Schönhense, Alice Kunin, Thomas K. Allison, Diana Y. Qiu
Moiré heterobilayers exhibiting spatially varying band alignment and electron and hole localization that can be precisely controlled through the twist angle have emerged as exciting platforms for studying complex quantum phenomena. While most heterobilayers of transition metal dichalcogenides (TMDs) have a type II band alignment, the introduction of type I band alignment could enable stronger light-matter coupling and enhanced radiative emission. Here, we show through a combination of first-principles GW plus Bethe Salpeter equation (GW-BSE) calculations and time- and angle-resolved photoemission spectroscopy (tr-ARPES) measurements that contrary to previous understanding, the MoSe2/WS2 heterobilayer has a type I band alignment at large twist angles and simultaneous regions of type I and type II band alignment due to the structural reconstruction in different high symmetry regions at small twist angles. In tr-ARPES, consistent with our calculations, a long-lived electron population is only observed in MoSe2 for samples with large twist angles, while in samples with small twist angles, signals from two distinct long-lived excitons are observed. Moreover, despite the near degeneracy of the conduction bands of the two layers, no excitonic hybridization occurs, suggesting that previously observed absorption peaks in this material arise from lattice reconstruction. Our findings clarify the complex energy landscape in MoSe2/WS2 heterostructures, where the coexistence of type I and type II band alignment opens the door to moiré-tunable optoelectronic devices with intrinsic lateral heterojunctions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Fast spin precession and strong perpendicular magnetic anisotropy in ferrimagnetic Mn4N thin films improved by Pd buffer layer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Yao Zhang, Yun Kim, Peter P. Murmu, Dingbin Huang, Deyuan Lyu, Jian-Ping Wang, Xiaojia Wang, Simon Granville
Ferrimagnets take the advantages of both ferromagnets and antiferromagnets making them promise for spintronic applications. Here we prepared ferrimagnetic Mn4N thin films with high Curie temperature and investigated the crystalline structure and magnetic properties affected by the Pd buffer layer. We demonstrated that both crystalline quality and perpendicular magnetic anisotropy (PMA) of Mn4N thin films are enhanced significantly due to the relaxation of tensile stress induced by the Pd buffer layer. We also demonstrated a fast spin precession at room temperature, almost 100 GHz, in Mn4N thin films. With the characteristics of high thermal stability, enhanced PMA by buffer layer and fast spin precession, Mn4N thin film is a promising material for spintronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Higher-order skyrmion crystal in van der Waals Kitaev triangular antiferromagnet NiI2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Chaebin Kim, Olivia Vilella, Youjin Lee, Pyeongjae Park, Yeochan An, Woonghee Cho, Matthew B. Stone, Alexander I. Kolesnikov, Shinichiro Asai, Shinichi Itoh, Takatsugu Masuda, Sakib Matin, Sujin Kim, Sung-Jin Kim, Martin Mourigal, Je-Geun Park
Topological spin textures, such as magnetic skyrmions, hold great promise for spintronics applications. However, most known skyrmion systems are restricted to a topological charge of one and require an external magnetic field for stabilization. Here, we report the discovery of a skyrmion crystal with a topological number of two in an insulating van der Waals magnet NiI2. We unveil the static and dynamic magnetic correlations across three temperature-driven magnetic phases using neutron scattering measurements, simulations, and model optimisation. By employing a minimal Kitaev-Heisenberg Hamiltonian, we reproduce the experimentally observed excitations and confirm the emergence of the higher-order skyrmion crystal through Monte Carlo simulations. Remarkably, this exotic phase arises without the need for a magnetic field, presenting a novel platform for controlling complex spin textures in an accessible material. These findings establish NiI2 as a pivotal material, bridging fundamental quantum magnetism with advancements in skyrmionics and multiferroic technologies.
Materials Science (cond-mat.mtrl-sci)
12 pages, 4 figures
Indexing current-voltage characteristics using a hash function
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
T. Tanamoto, S. Furukawa, R. Kitahara, T. Mizutani, K. Ono, T. Hiramoto
Differentiating between devices of the same size is essential for ensuring their reliability. However, identifying subtle differences can be challenging, particularly when the devices share similar characteristics, such as transistors on a wafer. To address this issue, we propose an indexing method for current-voltage characteristics that assigns proximity numbers to similar devices. Specifically, we demonstrate the application of the locality-sensitive hashing (LSH) algorithm to Coulomb blockade phenomena observed in PMOSFETs and nanowire transistors. In this approach, lengthy data on current characteristics are replaced with hashed IDs, facilitating identification of individual devices, and streamlining the management of a large number of devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 7 figures
Ultrathin Ga\(_2\)O\(_3\) Tunneling Contact for 2D Transition-metal Dichalcogenides Transistor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Yun Li, Tinghe Yun, Bohan Wei, Haoran Mu, Luojun Du, Nan Cui, Guangyu Zhang, Shenghuang Lin
The development of two-dimensional (2D) transition metal dichalcogenides (TMDs) based transistors has been constrained by high contact resistance and inadequate current delivery, primarily stemming from metal-induced gap states and Fermi level pinning. Research into addressing these challenges is essential for the advancing 2D transistors from laboratory experiments to industrial-grade production. In this work, we present amorphous Ga\(_2\)O\(_3\) as a novel tunneling contact layer for multilayer WS2-based field-effect transistors (FETs) to enhance electrical performance. The addition of this innovative tunneling layer avoid Schottky barrier forming while finally change into a tunneling barrier with the barrier height to just 3.7 meV, near-ideal ohmic contacts. This approach effectively reduces contact resistance to only 2.38 k\(\Omega\,\mu\)m and specific contact resistivity as low as \(3 \times 10^{-5}\) \(\Omega\)cm\(^2\). A record-high electron mobility of 296 cm\(^2\) V\(^{-1}\) s\(^{-1}\) and ON-OFF ratio over 106 are realized for WS\(_2\) transistor at room temperature. Compared to other tunneling materials, ultrathin Ga\(_2\)O\(_3\) layer offers scalability, cost-efficient production and broad substrate compatibility, making it well-suited for seamless integration with industrial wafer-scale electronics. A robust device performance remains highly consistent in a large-scale transistor array fabricated on \(1.5\times 1.5\) cm\(^2\) chips, with the average mobility closing to 200 cm\(^2\) V\(^{-1}\) s\(^{-1}\). These findings establish a new benchmark for contact performance in 2D transistors and prove the potential of tunneling contact engineering in advancing high-performance, scalable 29 pelectronics with promising applications in quantum computing and communication.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
29 pages, 5figures
Orbital Magnetism in Honeycomb Ladder
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Tomonari Mizoguchi, Soshun Ozaki, Hiroyasu Matsuura
We investigate the orbital magnetic susceptibility of the tight-binding model for the honeycomb ladder with the additional vertical hopping. Despite being one-dimensional, the magnetic flux penetrating the hexagonal rings affects the energetics of electrons, resulting in the finite orbital magnetic response. We find that the orbital magnetic susceptibility is sensitive to the parameters as well as the chemical potential. At half-filling, the response is diamagnetic when the system is close to the pure honeycomb ladder, whereas it turns to paramagnetic when it is close to the two-leg ladder. We also find several characteristic properties away from half-filling, such as the diamagnetic response at the band top and bottom, and the large paramagnetic response at the band gap sandwiched by the divergent density of states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 pages, 6 figures
Antiferromagnetic and bond-order-wave phases in the half-filled two-dimensional optical Su-Schrieffer-Heeger-Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Andy Tanjaroon Ly, Benjamin Cohen-Stead, Steven Johnston
Electron-phonon (\(e\)-ph) interactions arise in many strongly correlated quantum materials from the modulation of the nearest-neighbor hopping integrals, as in the celebrated Su-Schrieffer-Heeger (SSH) model. Nevertheless, relatively few non-perturbative studies of correlated SSH models have been conducted in dimensions greater than one, and those that have been done have primarily focused on bond models, where generalized displacements independently modulate each hopping integral. We conducted a sign-problem free determinant quantum Monte Carlo study of the optical SSH-Hubbard model on a two-dimensional square lattice, where site-centered phonon modes simultaneously modulate pairs of nearest-neighbor hopping integrals. We report the model's low-temperature phase diagram in the challenging adiabatic regime (\(\Omega/E_\mathrm{F} \sim 1/8\)). It exhibits insulating antiferromagnetic Mott and bond-order-wave (BOW) phases with a narrow region of coexistence between them. We also find that a critical \(e\)-ph coupling is required to stabilize the BOW phase in the small \(U\) limit. Lastly, in stark contrast to recent findings for the model's bond variant, we find no evidence for a long-range antiferromagnetism in the pure \((U/t=0)\) optical SSH model.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 5 pages of supplemental materials
Scale-free localization versus Anderson localization in unidirectional quasiperiodic lattices
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-21 20:00 EST
Scale-free localization emerging in non-Hermitian physics has recently garnered significant attention. In this work, we explore the interplay between scale-free localization and Anderson localization by investigating a unidirectional quasiperiodic model with generalized boundary conditions. We derive analytical expressions of Lyapunov exponent from the bulk equations. Together with the boundary equation, we can determine properties of eigenstates and spectrum and establish their exact relationships with the quasiperiodic potential strength and boundary parameter. While eigenstates exhibit scale-free localization in the weak disorder regime, they become localized in the strong disorder regime. The scale-free and Anderson localized states satisfy the boundary equation in distinct ways, leading to different localization properties and scaling behaviors. Generalizing our framework, we design a model with exact energy edges separating the scale-free and Anderson localized states via the mosaic modulation of quasiperiodic potentials. Our models can be realized experimentally in electric circuits.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
OBELiX: A Curated Dataset of Crystal Structures and Experimentally Measured Ionic Conductivities for Lithium Solid-State Electrolytes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Félix Therrien, Jamal Abou Haibeh, Divya Sharma, Rhiannon Hendley, Alex Hernández-García, Sun Sun, Alain Tchagang, Jiang Su, Samuel Huberman, Yoshua Bengio, Hongyu Guo, Homin Shin
Solid-state electrolyte batteries are expected to replace liquid electrolyte lithium-ion batteries in the near future thanks to their higher theoretical energy density and improved safety. However, their adoption is currently hindered by their lower effective ionic conductivity, a quantity that governs charge and discharge rates. Identifying highly ion-conductive materials using conventional theoretical calculations and experimental validation is both time-consuming and resource-intensive. While machine learning holds the promise to expedite this process, relevant ionic conductivity and structural data is scarce. Here, we present OBELiX, a domain-expert-curated database of $$600 synthesized solid electrolyte materials and their experimentally measured room temperature ionic conductivities gathered from literature. Each material is described by their measured composition, space group and lattice parameters. A full-crystal description in the form of a crystallographic information file (CIF) is provided for ~320 structures for which atomic positions were available. We discuss various statistics and features of the dataset and provide training and testing splits that avoid data leakage. Finally, we benchmark seven existing ML models on the task of predicting ionic conductivity and discuss their performance. The goal of this work is to facilitate the use of machine learning for solid-state electrolyte materials discovery.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
8 pages, 3 figures and 2 tables
Poincaré sphere engineering of dynamical ferroelectric topological solitons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Lingyuan Gao, Yijie Shen, Sergei Prokhorenko, Yousra Nahas, Laurent Bellaiche
Geometric representation lays the basis for understanding and flexible tuning of topological transitions in many physical systems. An example is given by the Poincaré sphere (PS) that provides an intuitive and continuous parameterization of the spin or orbital angular momentum (OAM) light states. Here, we apply this geometric construction to understand and continuously encode dynamical topologies of ferroelectric solitons driven by OAM-tunable light. We show that: (1) PS engineering enables controlled creation of dynamic polar antiskyrmions that are rarely found in ferroelectrics; (2) We link such topological transition to the tuning of the light beam as a ``knob'' from OAM (PS pole) to non-OAM (PS equator) modes; (3) Intermediate OAM-state structured light results in new ferroelectric topologies of temporally hybrid skyrmion-antiskyrmion states. Our study offers new approaches of robust control and flexible tuning of topologies of matter using structured light.
Materials Science (cond-mat.mtrl-sci)
Investigating the Optical and Thermodynamic Properties of 2D MoGe2P4 : Potential Material for Photothermal Therapy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Sudipta Saha, Arpan Sur, Labonno Saha, Md. Kawsar Alam
In this study, we analyzed the optical, thermodynamic and electronic properties of 2D MoGe2P4 from the first principle calculation. 2D MoGe2P4 demonstrates superior optical absorption in the NIR-I biological window (750 nm ~ 1000 nm) with a peak near 808 nm and excellent thermal conductivity (63 Wm-1K-1). Finite-difference time-domain (FDTD) simulations and Heat simulations demonstrate that 2D MoGe2P4 possesses efficient photothermal conversion under low laser power (0.5 W/cm2) which is operated in 808nm. Theoretical investigation demonstrates, rapid temperature elevation ({}T = 24.8 °C) of the 2D MoGe2P4 within two minutes and photothermal stability over multiple laser cycles, achieving temperatures suitable for effective photothermal therapeutic applications. Photothermal therapy (PTT) is an emerging tumor treatment technique that utilizes photothermal agents (PTAs) to convert near-infrared (NIR) light into localized heat for tumor ablation. To enhance biocompatibility, we analyzed the PEGylation of 2D MoGe2P4 nanosheets through molecular dynamics simulation. PEGylation at human body temperature was stable which signifies 2D MoGe2P4's prospect in therapeutic applications. This research highlights the potential of 2D MoGe2P4 as an emerging material for PTA, establishing a foundation for experimental and clinical trials.
Materials Science (cond-mat.mtrl-sci), Biomolecules (q-bio.BM)
Theoretical studies on the spin-charge dynamics in Kondo-lattice models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Masahito Mochizuki, Rintaro Eto
The Kondo-lattice model describes a typical spin-charge coupled system in which localized spins and itinerant electrons are strongly coupled via exchange interactions and exhibits a variety of long-wavelength magnetic orders originating from the nesting of Fermi surfaces. Recently, several magnetic materials that realize this model have been discovered experimentally, and they have turned out to exhibit rich topological magnetic phases including skyrmion crystals and hedgehog lattices. Our recent theoretical studies based on the large-scale spin-dynamics simulations have revealed several interesting nonequilibrium phenomena and excitation dynamics in the Kondo-lattice model, e.g., dynamical magnetic topology switching and peculiar spin-wave modes of the skyrmion crystals and the hedgehog lattices under irradiation with electromagnetic waves such as microwaves and light. These achievements are expected to open a new research field to explore novel nonequilibrium topological phenomena and related material functions of the spin-charge coupled magnets.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
14 pages, 11 figures, published in Activity Report FY2023 of Supercomputer Center, Institute for Solid State Physics, The University of Tokyo as an invited review article
Activity Report FY2023 Supercomputer Center, Institute for Solid State Physics, The University of Tokyo (ISSN 2188-5001), pp. 23-36
Nearly Complete Segregation of Submerged Grains in a Rotating Drum
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-21 20:00 EST
Yu Chen, Deheng Wei, Si Suo, Mingrui Dong, Yixiang Gan
Density-driven segregations, extensively studied in a simple rotating drum, are enriched with a wide range of underlying physics. Diverse symmetrical segregation patterns formed by mixing two types of dry mono-sized grains have been revealed due to variations in heavy and light grain densities, \(\rho_h\) and \(\rho_l\), and rotating speeds, \(\omega\). We engender experimentally a nearly complete segregation, not occurring in dry conditions of the same \(\rho_h\), \(\rho_l\), and \(\omega\), in submerged states. Further, based on the experiment-validated simulations, using coupled computational fluid dynamics and discrete element method, it is found the mixing index can be well predicted over a wide parameter space in the effective density ratio, \(D=(\rho_h-\rho_f)/(\rho_l-\rho_f)\) with \(\rho_f\) being the fluid density. Specifically, with increasing \(D\) well-mixed states transit to fully-segregated states with a rising number of vortices and severer asymmetrical patterns. When the global Reynolds number \(\mathrm{Re}_g\) is enlarged, the vortex area of heavy particles shrinks for lower \(D\), while the area of light particles gradually saturates; meanwhile, for higher \(D\) a new vortex with a continuously expanded area can be encountered in the light particle zone. These results improve our understanding of segregation transitions especially in submerged granular systems and shed new light on various science and engineering practices.
Soft Condensed Matter (cond-mat.soft)
12 pages, 4 figures
Real-space representation of the second Chern number
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
T. Shiina, F. Hamano, T. Fukui
We extend Kitaev's real-space formulation of the first Chern number to the second Chern number and establish a computational framework for its evaluation. To test its validity, we apply the derived formula to the disordered Wilson-Dirac model and analyze its ability to capture topological properties in the presence of disorder. Our results demonstrate that the real-space approach provides a viable method for characterizing higher-dimensional topological phases beyond momentum-space formulations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Lattice (hep-lat)
8 pages, 5 figures
Impact of Pressure and Apical Oxygen Vacancies on Superconductivity in La\(_3\)Ni\(_2\)O\(_7\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Chen Lu, Ming Zhang, Zhiming Pan, Congjun Wu, Fan Yang
The bilayer nickelate La\(_3\)Ni\(_2\)O\(_7\) under pressure has recently emerged as a promising system for high-\(T_c\) superconductivity (SC). In this work, we investigate the fate of the SC properties in La\(_3\)Ni\(_2\)O\(_{7}\) under pressure, focusing on the effects of structural deformation and apical oxygen vacancies. Employing a low-energy effective \(t\)-\(J_{\parallel}\)-\(J_{\perp}\) model for the \(3d_{x^2-y^2}\) orbitals within the slave-boson mean-field approach, we demonstrate that the SC pairing strength is significantly enhanced in the high-pressure tetragonal \(I4/mmm\) phase compared to the ambient pressure orthorhombic \(Amam\) phase. Furthermore, by simulating random configurations of apical oxygen vacancies, we show that oxygen vacancies suppress both pairing strength and superfluid density. These results underscore the critical role of pressure and oxygen stoichiometry in tuning the SC of La\(_3\)Ni\(_2\)O\(_7\), providing key insights into optimizing its high-\(T_c\) behavior.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 8 figures
Discovery of a new phase in thin flakes of KV\(_{3}\)Sb\(_{5}\) under pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Zheyu Wang, Lingfei Wang, King Yau Yip, Ying Kit Tsui, Tsz Fung Poon, Wenyan Wang, Chun Wai Tsang, Shanmin Wang, David Graf, Alexandre Pourret, Gabriel Seyfarth, Georg Knebel, Kwing To Lai, Wing Chi Yu, Wei Zhang, Swee K. Goh
We report results of magnetotransport measurements on KV\(_3\)Sb\(_5\) thin flakes under pressure. Our zero-field electrical resistance reveals an additional anomaly emerging under pressure (\(p\)), marking a previously unidentified phase boundary \(T^{\rm \ast}\)(\(p\)). Together with the established \(T_{\rm CDW}(p)\) and \(T_c(p)\), denoting the charge-density-wave transition and a superconducting transition, respectively, the temperature-pressure phase diagram of KV\(_3\)Sb\(_5\) features a rich interplay among multiple phases. The Hall coefficient evolves reasonably smoothly when crossing the \(T^{\rm \ast}\) phase boundary compared with the variation when crossing \(T_{\rm CDW}\), indicating the preservation of the pristine electronic structure. The mobility spectrum analysis provides further insights into distinguishing different phases. Finally, our high-pressure quantum oscillation studies up to 31 T combined with density functional theory calculations further demonstrate that the new phase does not reconstruct the Fermi surface, confirming that the translational symmetry of the pristine metallic state is preserved.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 5 figures. Advanced Science (2025)
Twinning in ferromagnetic Heusler Rh2MnSb epitaxial thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Artem Shamardin (1), Stanislav Cichoň (1), Esther de Prado (1), Jan Duchoň (1), Michal Rameš (1), Ladislav Fekete (1), Jaromír Kopeček (1), Šimon Šťastný (2), Aleš Melzer (2), Michal Hubert (2), Martin Veis (2), Ján Lančok (1), Oleg Heczko (1) ((1) Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18200, Czechia, (2) Institute of Physics of Charles University, Ke Karlovu 2026/5, Prague 12116, Czechia)
Epitaxially grown full Heusler alloy of Rh2MnSb thin films were prepared for the first time using DC magnetron sputtering. The films were deposited on MgO [001] substrates with a deposition temperature of 600°C, 700°C, and 800°C. We report the structural, morphological, optical, magneto-optical, and magnetic properties of the films with a 200 nm nominal thickness. The grown-at-600°C film was close to stoichiometric and exhibited L21 ordering typical for Heusler alloys. The single-phase Rh2MnSb film had a tetragonal structure with lattice parameters close to the bulk material. X-ray photoelectron spectroscopy revealed the metallic character of the film free from contamination. The tetragonal films exhibited discernible regular twinning with the majority of twin domains with the c-axis perpendicular to the surface due to a substrate constraint. The twin formation was studied by atomic force and transmission electron microscopy and by X-ray diffraction. Magnetic measurements showed TC of about 220-275 K and saturation magnetization of about 55 emu/g, close to the bulk material. Magneto-optical Kerr effect measurements of the film prepared at 600 °C affirmed paramagnetic behavior at room temperature and suggested the half-metallic behavior. The observed properties highlight the potential for further investigations of Rh2MnSb's thin films, focusing on compositional and structural control.
Materials Science (cond-mat.mtrl-sci)
17 pages, 11 figures
Walks in Rotation Spaces Return Home When Doubled and Scaled
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-21 20:00 EST
Jean-Pierre Eckmann, Tsvi Tlusty
The dynamics of numerous physical systems can be described as a series of rotation operations, i.e., walks in the manifold of the rotation group. A basic question with practical applications is how likely and under what conditions such walks return to the origin (the identity rotation), which means that the physical system returns to its initial state. In three dimensions, we show that almost every walk in SO(3), even a very complicated one, will preferentially return to the origin simply by traversing the walk twice in a row and uniformly scaling all rotation angles. We explain why traversing the walk only once almost never suffices to return, and comment on the problem in higher dimensions of SO(n).
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Dynamical Systems (math.DS)
Isotropic superconductivity in pressurized trilayer nickelate La4Ni3O10
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Di Peng, Yaolong Bian, Zhenfang Xing, Lixing Chen, Jiaqiang Cai, Tao Luo, Fujun Lan, Yuxin Liu, Yinghao Zhu, Enkang Zhang, Zhaosheng Wang, Yuping Sun, Yuzhu Wang, Xingya Wang, Chenyue Wang, Yuqi Yang, Yanping Yang, Hongliang Dong, Hongbo Lou, Zhidan Zeng, Zhi Zeng, Mingliang Tian, Jun Zhao, Qiaoshi Zeng, Jinglei Zhang, Ho-kwang Mao
Evidence of superconductivity (SC) has recently been reported in pressurized La3Ni2O7 and La4Ni3O10, providing a new platform to explore high-temperature superconductivity. However, while zero resistance state has been observed, experimental characterization of the superconducting properties of pressurized nickelates is still limited and experimentally challenging. Here, we present the first full temperature dependence of the upper critical field Hc2 measurement in La4Ni3O10 single crystal, achieved by combining high magnetic field and high-pressure techniques. Remarkably, the Hc2 of La4Ni3O10 is nearly isotropic, with the anisotropic parameter monotonically increasing from 1.4 near Tc to 1 at lower temperatures. By analyzing the Hc2 using the two-band model, we uncover that the anisotropic diffusivity of the bands, primarily originating from d(z2 ) and d(x2-y2 ) orbitals, is well compensated, resulting in an unusually isotropic superconducting state. These findings provide critical experimental evidence that underscores the significant role of the d(z2 ) orbital in enabling superconductivity in pressurized Ruddlesden-Popper nickelates.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 9 figures
Nodeless Superconducting State in the Presence of Zero-Field Staggered Magnetization in CeRh\(_{2}\)As\(_{2}\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
J. Juraszek, G. Chajewski, D. Kaczorowski, M. Konczykowski, D.F. Agterberg, T. Cichorek
The tetragonal heavy-fermion superconductor CeRh\(_{2}\)As\(_{2}\) with a critical temperature \(T_c\) \(\approx\) 0.34 K exhibits an intriguing magnetic field-induced transition between likely distinct superconducting states. In zero field, an even-parity state emerges within another ordered phase of unknown origin with \(T_0\) \(\approx\) 0.54 K. Here, we investigated the spin-singlet state of CeRh\(_{2}\)As\(_{2}\) at temperatures down to \(\approx\) 0.02\(T_c\) by means of local magnetization measurements performed using micro-Hall probe magnetometry. We determined the temperature dependencies of the lower critical field for both in-plane and out-of-plane field directions, and demonstrated their consistency with predominantly fully gapped superconductivity. In the magnetization measured along the \(a\) axis, we found a clear increase below \(T_0\), while no similar anomaly was observed along the \(c\) axis. Our results place important constraints on the spin-singlet order parameter in CeRh\(_{2}\)As\(_{2}\) and highlight an important role of static magnetic moments in the nature of \(T_0\) phase.
Superconductivity (cond-mat.supr-con)
19 pages, 12 figures
Electrically active defects in 3C, 4H and 6H silicon carbide polytypes: A review
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
This paper aims to critically review electrically active defects studied by junction spectroscopy techniques (deep-level transient spectroscopy and minority carrier transient spectroscopy) in the three most commonly used silicon carbide (SiC) polytypes: 3C-SiC, 4H-SiC, and 6H-SiC.
Materials Science (cond-mat.mtrl-sci)
22 pages, 10 figures
Localization versus incommemsurability for finite boson system in one-dimensional disordered lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-21 20:00 EST
Barnali Chakrabarti, Arnaldo Gammal
We explore the effect of disorder on a few-boson system in a finite one-dimensional quasiperiodic potential covering the full interaction ranging from uncorrelated to strongly correlated particles. We apply numerically exact multiconfigurational time-dependent Hartree for bosons to obtain the few-body emergent states in a finite lattice for both commensurate and incommensurate filling factors. The detailed characterization is done by the measures of one- and two-body correlations, fragmentation, order parameter. For commensurate filling, we trace the conventional fingerprints of disorder induced localization in the weakly interacting limit, however we observe robustness of fragmented and strongly correlated Mott in the disordered lattice. For filling factor smaller than one, we observe existing delocalization fraction of particles interplay in a complex way. For strongly interacting limit, the introduced disorder drags the fragmented superfluid of primary lattice to Mott localization. For filling factor larger than one in the primary lattice, the extra delocalization always resides on commensurate background of Mott-insulator. We observe beyond Bose-Hubbard physics in the fermionization limit when the pairing bosons fragment into two orbitals -- Mott dimerization happens. The introduced disorder first relocates the dimers, then strong disorder starts to interfere with the background Mott correlation. These findings unlock a rich landscape of unexplored localization process in the quasiperiodic potentials and pave the way for engineering exotic quantum many-body states with ultracold atoms.
Quantum Gases (cond-mat.quant-gas)
Thermal conductance at superradiant phase transition in quantum Rabi model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Tsuyoshi Yamamoto, Yasuhiro Tokura
The quantum Rabi model exhibits a superradiant phase transition when the coupling becomes strong, even though it involves only two components: a two-level atom and a single bosonic mode. This phase transition is referred to as a few-body quantum phase transition, in contrast to conventional phase transitions in many-body systems. In this work, we investigate heat transport across an atom embedded in bosonic modes, modeled by the quantum Rabi model, between two thermal baths. We found a manifestation of the superradiant phase transition in the thermal conductance, which represents the linear response to a temperature bias. Our work can be helpful for the development of quantum heat devices utilizing controllable few-body phase transitions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
6+5 pages, 3 figures
Active energy harvesting and work transduction by hair-cell bundles in bullfrog's inner ear
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-21 20:00 EST
Yanathip Thipmaungprom, Laila Saliekh, Rodrigo Alonso, Édgar Roldán, Florian Berger, Roman Belousov
Hair cells actively drive oscillations of their mechanosensitive organelles -- the hair bundles that enable hearing and balance sensing in vertebrates. Why and how some hair cells expend energy by sustaining this oscillatory motion in order to fulfill their function as signal sensors and others -- as amplifiers, remains unknown. We develop a stochastic thermodynamic theory to describe energy flows in a periodically-driven hair bundle. Our analysis of thermodynamic fluxes associated with hair bundles' motion and external sinusoidal stimulus reveals that these organelles operate as thermodynamic work-to-work machines under different operational modes. One operational mode transduces the signal's power into the cell, whereas another allows the external stimulus to harvest the energy supplied by the cell. These two regimes might represent thermodynamic signatures of signal sensing and amplification respectively. In addition to work transduction and energy harvesting, our model also substantiates the capability of hair-cell bundles to operate as heaters and and active feedback refrigerators at the expense of external driving. We quantify the performance and robustness of the work-to-work operating modes of hair bundles revealing a maximal thermodynamic efficiency of around 80 percent of the transduced work.
Statistical Mechanics (cond-mat.stat-mech), Cell Behavior (q-bio.CB)
38 pages, 20 figures, 10 tables
Resonant current from singlet-triplet state mixing in coupled quantum dots
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Electrically driven spin resonances in double quantum dots can lift the spin blockade and give rise to a resonant current. This current can probe the properties of coupled two-spin states for different quantum dot configurations. Using a Floquet-Markov quantum transport model we compute the resonant current for different driving amplitudes and ac field frequencies in spin-orbit coupled quantum dots. We show that the resonant current has a very rich interference pattern which can give valuable insight into the singlet-triplet state mixing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nontrivial damping of magnetization currents in perturbed spin chains
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-21 20:00 EST
Mariel Kempa, Markus Kraft, Jiaozi Wang, Robin Steinigeweg
Since perturbations are omnipresent in physics, understanding their impact on the dynamics of quantum many-body systems is a vitally important but notoriously difficult question. On the one hand, random-matrix and typicality arguments suggest a rather simple damping in the overwhelming majority of cases, e.g., exponential damping according to Fermi's Golden Rule. On the other hand, counterexamples are known to exist, and it remains unclear how frequent and under which conditions such counterexamples appear. In our work, we consider the spin-1/2 XXZ chain as a paradigmatic example of a quantum many-body system and study the dynamics of the magnetization current in the easy-axis regime. Using numerical simulations based on dynamical quantum typicality, we show that the standard autocorrelation function is damped in a nontrivial way and that only a modified version of this function is damped in a simple manner. Employing projection-operator techniques in addition, we demonstrate that both, the nontrivial and simple damping relation can be understood on perturbative grounds. Our results are in agreement with earlier findings for the particle current in the Hubbard chain.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 10 figures
Lattice distortion tuning resistivity invar effect in high entropy alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Hao Chen, Yuanji Xu, Lihua Liu, Yue Chen, Jan Wróbel, Daoyong Cong, Fuyang Tian
Materials with an ultra-low temperature coefficient of resistivity are desired for the temperature and flow sensors in high-precision electronic measuring systems. In this work, the Kubo-Greenwood formula, implemented in ab initio molecular dynamics simulations, is employed to predict the finite-temperature resistivity of multi-component alloys with severe lattice distortion. We observe a tiny change in resistivity over a wide temperature range in high-entropy alloys. The electronic resistivity invar effect in B2 Ni\(_{25}\)Co\(_{25}\)(HfTiZr)\(_{50}\) Elinvar alloys results from a balance between intrinsic and residual resistivity. This effect is associated with atomic displacements from ideal lattice sites, which are caused by lattice thermal vibrations and chemical disorder-induced lattice distortions. It is further evidenced by a decrease in lattice distortion with temperature and changes in the electronic density of states.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
The diffusive dynamics and electrochemical regulation of weak polyelectrolytes across liquid interfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-21 20:00 EST
Giulia Laura Celora, Ralf Blossey, Andreas Munch, Barbara Wagner
We propose a framework to study the spatio-temporal evolution of liquid-liquid phase separation of weak polyelectrolytes in ionic solutions. Unlike strong polyelectrolytes, which carry a fixed charge, the charge state of weak polyelectrolytes is modulated by the electrochemical environment through protonation and deprotonation processes. Leveraging numerical simulations and analysis, our work reveals how solution acidity (pH) influences the formation, interactions, and structural properties of phase-separated coacervates. We find that pH gradients can be maintained across coacervate interfaces resulting in a clear distinction in the electro-chemical properties within and outside the coacervate. By regulating the charge state of weak polyelectrolytes, pH gradients interact and modulate the electric double layer forming at coacervate interfaces eventually determining how they interact. Further linear and nonlinear analyses of stationary localised solutions reveal a rich spectrum of behaviours that significantly distinguish weak from strong polyelectrolytes. Overall, our results demonstrate the importance of charge regulation on phase-separating solutions of charge-bearing molecules and the possibility of harnessing charge-regulated mechanisms to control coacervates and shape their stability and spatial organisation.
Soft Condensed Matter (cond-mat.soft), Adaptation and Self-Organizing Systems (nlin.AO), Pattern Formation and Solitons (nlin.PS), Biomolecules (q-bio.BM)
Semiconducting and superconducting properties of 2D hexagonal materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Dominik Szczȩśniak, Jakub T. Gnyp, Marta Kielak
The beginning of high interest in two-dimensional (2D) crystals is marked by the synthesis of graphene, which constitutes exemplary monolayer material. This is due to the multiple extraordinary properties of graphene, particularly in the field of quantum electronic phenomena. However, there are electronic features that are notably missing in this material due to the inherent nature of its charge carriers. Of particular importance is that pristine graphene does not exhibit semiconducting or superconducting properties, preventing related applications. Certain modifications to graphene or even synthesis of sibling materials is needed to arrive with semiconducting and superconducting 2D hexagonal materials. Here, the representative examples of such materials are discussed in detail along with their expected properties. Special attention is given to the unique semiconducting and superconducting phenomena found in these materials e.g. the non-adiabatic superconductivity, spin- and valley-dependent conductivity or the bulk-like Schottky-type potential barriers. The discussion is supplemented with some pertinent conclusions and perspectives for future work.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
4 pages, 2 figures
Discovery of an Intermediate Nematic State in a Bilayer Kagome Metal ScV6Sn6
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Camron Farhang, William R. Meier, Weihang Lu, Jiangxu Li, Yudong Wu, Shirin Mozaffari, Richa P. Madhogaria, Yang Zhang, David Mandrus, Jing Xia
Nematicity, where rotational symmetry of the crystal lattice is spontaneously broken, is a ubiquitous phenomenon in correlated quantum matter, often intertwining with other orders to produce a richer spectrum of phases. Here we report a new phase transition in high-quality ScV6Sn6 bilayer kagome metal at a temperature T^, occurring seven Kelvins below the charge density wave (CDW) transition at T_CDW, as indicated by thermodynamic, transport, and optical measurements. This emerging intermediate phase does not exhibit spontaneous time-reversal-symmetry breaking, as evidenced by zero-field Sagnac interferometer experiments. However, it displays a strong, spontaneous (strain- and field-free) anisotropy in the kagome plane between T^and T_CDW, as revealed by transport and optical polarization rotation measurements. Additionally, a pronounced depolarization effect detected by the Sagnac interferometer further confirms its nematic nature. This intermediate nematic phase, alongside the recently discovered intra-unit cell nematic order at much lower temperatures, presents a diverse landscape of nematicities at multiple length and temperature scales, distinguishing it from those observed in kagome metals AV3Sb5. Our findings highlight ScV6Sn6 and the broader RM6X6 intermetallic family as fertile platforms for realizing symmetry-breaking phases driven by a unique interplay of competing CDW instabilities, kagome physics, and Van Hove singularities.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Non-Hermitian linear perturbation to a Hamiltonian with a constant electromagnetic field and Hall conductivity
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
The quantum Hall effect led to the classification of materials as topological insulators, and the generalization of this classification to non-Hermitian band theory is an active area of research. While the impact of non-Hermitian perturbations on Weyl Hamiltonians is expected to provide valuable insights for classifying topological phase transitions, predicting the effect of non-Hermiticity on Hall conductivity remains complex. In fact, previous theoretical work has shown that the quantization of Hall conductivity in the quantum anomalous Hall effect is lost, even though it is classified as a non-Hermitian Chern insulator. In this work, the stationary Schrödinger equation for an electron in a constant electromagnetic field with a non-Hermitian linear perturbation is studied. The wave function and the spectrum of the system are derived analytically, with the spectrum consisting of Landau levels modified by an additional term associated with the linear Stark effect, proportional to a complex constant \(\lambda\). It is shown that this constant arises from an operator \(\hat{\Pi}\) that commutes with the Hamiltonian, i.e., \(\hat{\Pi}\) is a symmetry of the system. Finally, the Hall conductivity for the lowest Landau level is calculated, showing that it remains exactly equal to the inverse of Klitzing's constant despite the perturbation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Mesoscopic heterogeneity in biomolecular condensates from sequence patterning
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-21 20:00 EST
Luke K. Davis, Andrew J. Baldwin, Philip Pearce
Biomolecular condensates composed of intrinsically disordered proteins (IDPs) are vital for proper cellular function, and their dysfunction is associated with diseases including neurodegeneration and cancer. Despite their biological importance, the precise physical mechanisms underlying condensate (dys)function are unclear, in part owing to the difficulties in understanding how biomolecular sequence patterns influence emergent condensate behaviours across relevant length and timescales. Here, through minimal physical modelling, we explain how IDP sequence patterning gives rise to nano-scale organisational heterogeneities in condensates. By applying our coarse-grained molecular-dynamics polymer model, which accounts for steric, attractive, and electrostatic interactions, we systematically quantify and map out the emergent morphological phases resulting from a wide range of sequence patterns. We demonstrate how sequences that enable local coil-to-globule transitions within regions of single polymers - driven by a competition between the preferred crowding densities of different regions in the sequence - also exhibit cluster formation in condensates. Overall, our work provides a conceptual framework to understand how sequence properties determine mesoscopic organisation within biomolecular condensates.
Soft Condensed Matter (cond-mat.soft)
Superlative spin transport of holes in ultra-thin black phosphorus
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Jiawei Liu, Deyi Fu, Tingyu Qu, Deqiang Zhang, Kenji Watanabe, Takashi Taniguchi, Ahmet Avsar, Barbaros Ozyilmaz
The development of energy-efficient spin-based hybrid devices that can perform functions such as logic, communication, and storage requires the ability to control and transport highly polarized spin currents over long distances in semiconductors. While traditional semiconductors such as silicon support spin transport, the effects of carrier type and concentration on important spin parameters are not well understood due to the need for extrinsic doping, which can cause additional momentum and hence spin scattering. Two-dimensional semiconductors, on the other hand, offer the ability to tune carrier type and concentration through field effect gating and inherently have long intrinsic spin lifetimes, making them a desirable platform for spin transport. Here, we study gate-tunable spin transport across narrow band-gap black phosphorus-based spin valves which enable us to systematically investigate spin transport with varying hole and electron concentrations under non-local geometry. Our findings demonstrate exceptional pure spin transport that approaches intrinsic limit, particularly in the low hole doping range. We achieved record non-local signals reaching 350 {} and spin lifetimes exceeding 16 ns. Contrary to the behaviour seen in typical semiconductors, we find that the spin transport performance of holes in black phosphorus is significantly better than that of electrons, with the Elliott-Yafet process being the primary spin scattering mechanism. The observation of gate-tunable nanosecond spin lifetimes and colossal pure spin signals in both p- and n-type black phosphorus offers promising prospects for the development of novel semiconducting spintronics devices requiring sharp p-n interfaces.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Strong-coupling high-\(T_{\rm c}\) superconductivity in doped correlated band insulator
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Yusuke Nomura, Motoharu Kitatani, Shiro Sakai, Ryotaro Arita
We explore the superconducting properties of the bilayer Hubbard model, which exhibits a high transition temperature (\(T_{\rm c}\)) for an \(s_{\pm}\) pairing, using a cluster extension of the dynamical mean-field theory. Unlike the single-layer Hubbard model, where the \(d\)-wave superconductivity emerges by doping the Mott insulator, the parent state of the bilayer system is a correlated band insulator. Above \(T_{\rm c}\), slight hole (electron) doping introduces a striking dichotomy between electron and hole pockets: the electron (hole) pocket develops a pseudogap while the other becomes a nearly incipient band. We reveal that the superconductivity is driven by kinetic (potential) energy gain in the underdoped (overdoped) region. We also find a very short coherence length, for which we argue the relevance to multi-orbital physics. Our study offers crucial insights into the superconductivity in the bilayer Hubbard model potentially relevant to La\(_3\)Ni\(_2\)O\(_7\).
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
8 pages including Supplemental Materials, 4 figures
Topological phase transition through tunable nearest-neighbor interactions in a one-dimensional lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-21 20:00 EST
Rajashri Parida, Diptiman Sen, Tapan Mishra
We investigate the phase diagram of a one-dimensional model of hardcore bosons or spinless fermions with tunable nearest-neighbor interactions. By introducing alternating repulsive and attractive interactions on consecutive bonds, we show that the system undergoes a transition from a bond-ordered (BO) phase to a charge-density wave-II (CDW-II) phase as the attractive interaction strength increases at a fixed repulsive interaction. For a specific interaction pattern, the BO phase exhibits topological properties, which vanish when the pattern is altered, leading to a transition from a topological BO phase to a trivial BO phase through a gap-closing point where both interactions vanish. We identify these phases using a combination of order parameters, topological invariants, edge-state analysis and Thouless charge pumping. By extending our analysis beyond half-filling, we explore the phase diagram across all densities and identify the superfluid (SF) and the pair-superfluid (PSF) phases, characterized by single-particle and bound-pair excitations at incommensurate densities. The proposed model is experimentally realizable in platforms such as Rydberg excited or ultracold atoms in optical lattices, offering a versatile framework to study such interplay between topology and interactions in low-dimensional systems.
Quantum Gases (cond-mat.quant-gas), Other Condensed Matter (cond-mat.other)
17 pages, 18 figures
Emergent Goldstone flat bands and spontaneous symmetry breaking with type-B Goldstone modes
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-21 20:00 EST
Huan-Qiang Zhou, Jesse J. Osborne, Qian-Qian Shi, Ian P. McCulloch
For a quantum many-body spin system undergoing spontaneous symmetry breaking with type-B Goldstone modes, a high degree of degeneracy arises in the ground state manifold. Generically, if this degeneracy is polynomial in system size, then it does not depend on the type of boundary conditions used. However, if there exists an emergent (local) symmetry operation tailored to a specific degenerate ground state, then we show that the degeneracies are exponential in system size and are different under periodic boundary conditions (PBCs) and open boundary conditions (OBCs). We further show that the exponential ground state degeneracies in turn imply the emergence of Goldstone flat bands -- single-mode excitations generated by a multi-site operator and its images under the repeated action of the translation operation under PBCs or the cyclic permutation symmetry operation under OBCs. Conversely, we also show that the presence of emergent Goldstone flat bands implies that there exists an emergent (local) symmetry operation tailored to a specific degenerate ground state. In addition, we propose an extrinsic characterization of emergent Goldstone flat bands, revealing a connection to quantum many-body scars, which violate the eigenstate thermalization hypothesis. We illustrate this by presenting examples from the staggered \({\rm SU}(4)\) spin-1 ferromagnetic biquadratic model and the staggered \({\rm SU}(4)\) ferromagnetic spin-orbital model. We also perform extensive numerical simulations for the more general \({\rm SO}(3)\) spin-1 bilinear-biquadratic and \({\rm SO(4)}\) ferromagnetic spin-orbital models, containing the two aforementioned models as the endpoints in the ferromagnetic regimes respectively, and confirm the emergence of Goldstone flat bands, as we approach these endpoints from deep inside the ferromagnetic regimes.
Strongly Correlated Electrons (cond-mat.str-el)
30 pages, 7 figures
Optimizing Lead-Free Chalcogenide Perovskites for High-Efficiency Photovoltaics via Alloying Strategies
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Surajit Adhikari, Priya Johari
Lead-free chalcogenide perovskites are emerging as game-changers in the race for sustainable, high-performance photovoltaics. These materials offer a perfect trifecta: non-toxic elemental composition, exceptional phase stability, and outstanding optoelectronic properties. However, unlocking their full potential for solar cell applications requires advanced strategies to fine-tune their electronic and optical behavior. In this study, we take CaHfS\(_{3}\)-a promising but underexplored candidate-and revolutionize its performance by introducing targeted substitutions: Ti at the cation site and Se at the anion site. Using cutting-edge computational techniques, including density functional theory, GW calculations, and the Bethe-Salpeter equation (BSE), we reveal how these substitutions transform the material's properties. Our findings highlight that alloyed compounds such as CaHfS\(_{3-x}\)Se\(_{x}\) and CaHf\(_{1-y}\)Ti\(_{y}\)X\(_{3}\) (X = S, Se) are not only phase-stable but also feature adjustable direct G\(_{0}\)W\(_{0}\)@PBE bandgaps (1.29-2.67 eV), reduced exciton binding energies, and significantly improved polaron mobility. These modifications enable better light absorption, reduced electron-hole recombination, longer exciton lifetimes, and enhanced quantum yield. Impressively, the alloyed perovskites, specifically, for the Ti-rich Se-based perovskites, achieve a spectroscopic-limited maximum efficiency of up to 28.06%, outperforming traditional lead-based halide perovskites. Our results demonstrate that strategic alloying is a powerful tool to supercharge the optoelectronic properties of lead-free chalcogenide perovskites, positioning them as strong contenders for next-generation photovoltaic technologies.
Materials Science (cond-mat.mtrl-sci)
16 pages, 6 figures, 4 tables
Superconductivity Favored Anisotropic Phase Stiffness in Infinite-Layer Nickelates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Minyi Xu, Dong Qiu, Minghui Xu, Yehao Guo, Cheng Shen, Chao Yang, Wenjie Sun, Yuefeng Nie, Zi-Xiang Li, Tao Xiang, Liang Qiao, Jie Xiong, Yanrong Li
In unconventional superconductors such as cuprates and iron pnictides and chalcogenides, phase stiffness - a measure of the energy cost associated with superconducting phase variations - is on the same order of magnitude as the strength of Cooper pairing, translating to superconductivity governed by phase fluctuations. However, due to a lack of a direct experimental probe, there remains a fundamental gap in establishing microscopic picture between unconventional superconductivity and phase fluctuations. Here we show a vector current technique that allows for in-situ angle-resolved transport measurements, providing exclusive evidence suggesting an anisotropic nature of phase stiffness in infinite-layer nickelate superconductors. Pronounced anisotropy of in-plane resistance manifests itself in both normal and superconducting transition states, indicating crystal symmetry breaking. Remarkably, the electric conductivity of Nd0.8Sr0.2NiO2 peaks at 125° between the direction of the current and crystal principal axis, but this angle evolves to 160° near zero-resistance temperature. Further measurements reveal that the superconductivity is favored along a direction with minimized phase fluctuations, an orientation strikingly deviating from the symmetric direction imposed by both electronic anisotropy and the underlying crystal lattice. Identical measurements conducted on a prototypical cuprate superconductor yield consistent results, suggesting that this previously unknown behavior could be ubiquitous. By shielding insight into the contrasting anisotropy between electron fluid and superfluid, our findings provide clues for a unified framework for understanding unconventional superconductors
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Quantum fluctuations-driven Melting Transitions in Two-dimensional Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-21 20:00 EST
Dong Qiu, Yuting Zou, Chao Yang, Dongxing Zheng, Chenhui Zhang, Deju Zhang, Yuhang Wu, Gaofeng Rao, Peng Li, Yuqiao Zhou, Xian Jian, Haoran Wei, Zhigang Cheng, Xixiang Zhang, Yanning Zhang, Haiwen Liu, Jingbo Qi, Yanrong Li, Jie Xiong
Quantum fluctuations are pivotal in driving quantum phase transitions, exemplified by the quantum melting of Wigner crystals into Fermi liquids in electron systems. However, their impact on superconducting systems near zero temperature, particularly in the superconductor-insulator/metal transition, remains poorly understood. In this study, through electric transport measurements on the two-dimensional (2D) superconductor (SnS)1.17NbS2, we demonstrate that quantum fluctuations induce vortex displacement from their mean position, leading to the quantum melting of vortex solid near zero temperature. Quantitative analysis reveals the magnetic field-induced anomalous metal originates from this quantum melting transition, with energy dissipation governed by quantum fluctuations-driven vortex displacements. Remarkably, further extending this analysis to various 2D superconductors yields the same results, and many properties of anomalous metal can be qualitatively understood within the framework of quantum melting. The connection between the quantum melting of vortex solids and dissipative anomalous metal opens a novel pathway towards understanding quantum phase transitions through vortex dynamics, providing new insights on both fields.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Nonadiabatic quantum geometry and optical conductivity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
The ground-state quantum geometry is at the root of several static and adiabatic properties, while genuinely dynamic properties are routinely addressed via Kubo formulae, whose essential entries are the excited states. It is shown here that the ground-state metric-curvature tensor evolves in time by means of a causal unitary operator, which by construction elucidates the geometrical effect of the excited states in compact form. In the condensed-matter case the generalized tensor encompasses the whole conductivity tensor at arbitrary frequencies in both insulators and metals, with the exception of the Drude term in the metallic case; the latter is shown to be eminently nongeometrical.
Materials Science (cond-mat.mtrl-sci)
4 pages + 1 page Supplemental
Unlocking the Optoelectronic Potential of AGeX\(_{3}\) (A = Ca, Sr, Ba; X = S, Se): A Sustainable Alternative in Chalcogenide Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Ayan Chakravorty, Surajit Adhikari, Priya Johari
The quest for environmentally benign and stable optoelectronic materials has intensified, and chalcogenide perovskites (CPs) have emerged as promising candidates owing to their non-toxic composition, stability, small bandgaps, large absorption coefficients. However, a detailed theoretical study of excitonic and polaronic properties of these materials remains underexplored due to high computational demands. Herein, we present a comprehensive theoretical investigation of Germanium-based CPs, AGeX\(_{3}\) (A = Ca, Sr, Ba; X = S, Se), which adopt distorted perovskite structures (-phase) with an orthorhombic crystal structure (space group : Pnma) by utilizing state-of-the-art density functional theory (DFT), density functional perturbation theory (DFPT), and many-body perturbation theory (GW and Bethe-Salpeter equation). Our calculations reveal that these materials are thermodynamically and mechanically stable, with the bandgaps calculated using G\(_{0}\)W\(_{0}\)@PBE ranging from 0.646 to 2.001 eV - suitable for optoelectronic devices. We analyze the ionic and electronic contributions to dielectric screening using DFPT and BSE methods, finding that the electronic component dominates. The exciton binding energies range from 0.03 to 73.63 meV, indicating efficient exciton dissociation under ambient conditions. Additionally, these perovskites exhibit low to high polaronic mobilities (1.67-167.65 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\)), exceeding many lead-free CPs and halide perovskites due to reduced carrier-phonon interactions. The unique combination of wide tunable bandgaps, low exciton binding energies, and enhanced charge-carrier mobility highlights AGeX\(_{3}\) as a potential material for next-generation optoelectronic applications. These compounds are stable, high-performing, and eco-friendly, showing great promise for experimental realization and device integration.
Materials Science (cond-mat.mtrl-sci)
12 pages, 4 figures, 5 tables
Discovery of transient topological crystalline order in optically driven SnSe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Masataka Mogi, Dongsung Choi, Kyoung Hun Oh, Diana Golovanova, Yufei Zhao, Yifan Su, Zongqi Shen, Doron Azoury, Haoyu Xia, Batyr Ilyas, Tianchuang Luo, Noriaki Kida, Taito Osaka, Tadashi Togashi, Binghai Yan, Nuh Gedik
Ultrafast optical excitation of quantum materials has opened new frontiers for transiently inducing novel phases of matter, including magnetism, charge density waves, ferroelectricity, and superconductivity beyond the constraints of equilibrium thermodynamics. Triggering a transient topological order in a trivial semiconductor represents a key milestone, as it could provide an on-demand route to topological functionality for device applications. However, achieving a topologically nontrivial phase from a large-gap (~ 1 eV) semiconductor remains a major challenge, as substantial energy modification is required to invert the band gap. Here, we report the discovery of a thermally inaccessible, transient topological crystalline order in a sizable-gap (~ 0.8 eV) layered semiconductor, SnSe, through femtosecond above-gap excitation. Time- and angle-resolved photoemission spectroscopy reveals a Dirac-like linear dispersion forming within the band gap on a subpicosecond timescale. This transient state shows hallmark features of a reflection-invariant topological crystalline insulator, including a high Fermi velocity (2.5x10^5 m/s), multiple Dirac points located away from high-symmetry momenta, and independence from probe photon energy, persisting for several picoseconds even at room temperature. Our findings establish a nonequilibrium pathway to ultrafast topological order in a semiconductor, opening new avenues for optically driven spintronic and quantum information technologies.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
24 pages, 4 figures
Identification of soft modes in amorphous Al\(_{2}\)O\(_{3}\) via first-principles
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
Alexander C. Tyner, Joshuah T. Heath, Thue Christian Thann, Vincent P. Michal, Peter Krogstrup, Mark Kamper Svendsen, Alexander V. Balatsky
Amorphous Al\(_{2}\)O\(_{3}\) is a fundamental component of modern superconducting qubits. While amphorphous oxides offer distinct advantages, such as directional isotropy and a consistent bulk electronic gap, in realistic systems these compounds support two-level systems (TLSs) which couple to the qubit, expediting decoherence. In this work, we perform a first-principles study of amorphous Al\(_{2}\)O\(_{3}\) and identify low-energy modes in the electronic and phonon spectra as a possible origin for TLSs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
5+1 Pages, 7 + 3 Figures
Slave-spin approach to the Anderson-Josephson quantum dot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-21 20:00 EST
We study a strongly interacting quantum dot connected to two superconducting leads using a slave-spin representation of the dot. At the mean-field level the problem maps into a resonant level model with superconducting leads, coupled to an auxiliary spin-1/2 variable accounting for the parity of the dot. We obtain the mean-field phase diagram, showing a transition between a Kondo (singlet) and a local moment (doublet) regime, corresponding to the \(0-\pi\) transition of the junction. The mean-field theory qualitatively captures the Kondo singlet phase and its competition with superconductivity for weak values of the BCS gap, including the non-trivial dependence of the Andreev bound states on the interaction, but fails in the doublet regime where it predicts a dot decoupled from the bath. Using diagrammatic techniques and a random phase approximation, we include fluctuations on top of the mean-field theory to describe finite-frequency dynamics of the effective spin variable. This leads to the formation of high-energy Hubbard bands in the spectral function and a coherent Kondo peak with a BCS gap at low energies. Finally, we compute the Josephson current and the induced superconducting correlations on the dot.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Spatial and Temporal Periodic Density Patterns in Driven Bose-Einstein Condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-21 20:00 EST
A. del Río-Lima, J. A. Seman, R. Jáuregui, F. J. Poveda-Cuevas
The study of collective excitations is a crucial tool for understanding many-body quantum systems. For instance, they play a central role in the exploration of superfluidity and other quantum macroscopic phenomena in Bose and Fermi systems. In this work we present a variational and a numerical study of a parametrically driven Bose-Einstein condensate confined in a cylindrical harmonic trap in which the aspect ratio can be varied from a prolate (cigar-shaped) to an oblate (pancake-shaped) system. The excitation can be applied by periodically modulating the harmonic frequencies of the trap or, alternatively, the interatomic interaction strength at a frequency that matches that of the system breathing mode. As a result, we observe the formation of dynamical density patterns that depend on the geometry of the trap: a fringe pattern in a prolate system and a ring pattern in an oblate one. By decomposing the total energy into its kinetic, potential, and interaction terms, we show that the onset of these patterns coincides with the redistribution of kinetic energy along the weakly trapped directions of the sample, indicating the three-dimensional nature of the studied phenomena. Finally, our analysis shows that the difference between the two excitation mechanisms lies on the system stability. Modulating the trap destabilizes the system quicker than modulating the interactions, leading to earlier formation of the patterns.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
Physical Review A 110, 053318 (2024)
Stacking-dependent topological electronic structures in honeycomb-kagome heterolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-21 20:00 EST
Chan Bin Bark, Hanbyul Kim, Seik Pak, Hong-Guk Min, Sungkyun Ahn, Youngkuk Kim, Moon Jip Park
Heterostructures of stacked two-dimensional lattices have shown great promise for engineering novel material properties. As an archetypal example of such a system, the hexagon-shared honeycomb-kagome lattice has been experimentally synthesized in various material platforms. In this work, we explore three rotationally symmetric variants of the honeycomb-kagome lattice: the hexagonal, triagonal, and biaxial phases. While the triagonal and biaxial phases exhibit trivial insulating and Dirac semimetal band structures, respectively, the hexagonal phase hosts a higher-order topological phase driven by band inversion near the \(\Gamma\)-point. This highlights a key distinction from the conventional band inversions at the \(K\)-point observed in hexagonal homobilayer systems. Furthermore, we demonstrate how the distinct topological properties of these phases result in network band structures within moiré heterostructures formed by twisted or lattice-mismatched HK systems. These network band structures can be experimentally observed through extrinsic twisting or intrinsic lattice mismatching between the honeycomb and kagome systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 9 figures
Emergence of Fermi's Golden Rule in the Probing of a Quantum Many-Body System
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-21 20:00 EST
Jianyi Chen, Songtao Huang, Yunpeng Ji, Grant L. Schumacher, Alan Tsidilkovski, Alexander Schuckert, Gabriel G. T. Assumpção, Nir Navon
Fermi's Golden Rule (FGR) is one of the most impactful formulas in quantum mechanics, providing a link between easy-to-measure observables - such as transition rates - and fundamental microscopic properties - such as density of states or spectral functions. Its validity relies on three key assumptions: the existence of a continuum, an appropriate time window, and a weak coupling. Understanding the regime of validity of FGR is critical for the proper interpretation of most spectroscopic experiments. While the assumptions underlying FGR are straightforward to analyze in simple models, their applicability is significantly more complex in quantum many-body systems. Here, we observe the emergence and breakdown of FGR, using a strongly interacting homogeneous spin-\(1/2\) Fermi gas coupled to a radio-frequency (rf) field. Measuring the transition probability into an outcoupled internal state, we map the system's dynamical response diagram versus the rf-pulse duration \(t\) and Rabi frequency \(\Omega_0\). For weak drives, we identify three regimes: an early-time regime where the transition probability takes off as \(t^2\), an intermediate-time FGR regime, and a long-time non-perturbative regime. Beyond a threshold Rabi frequency, Rabi oscillations appear. Our results provide a blueprint for the applicability of linear response theory to the spectroscopy of quantum many-body systems.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)