CMP Journal 2025-02-11
Statistics
Physical Review Letters: 7
Physical Review X: 1
arXiv: 96
Physical Review Letters
Complete Dispersive Evaluation of the Hadronic Light-by-Light Contribution to Muon \(g- 2\)
Research article | Chiral perturbation theory | 2025-02-11 05:00 EST
Martin Hoferichter, Peter Stoffer, and Maximilian Zillinger
Hadronic light-by-light (HLbL) scattering defines one of the critical contributions in the Standard Model prediction of the anomalous magnetic moment of the muon. In this Letter, we present a complete evaluation using a dispersive formalism, in which the HLbL tensor is reconstructed from its discontinuities, expressed in terms of simpler hadronic matrix elements that can be extracted from experiment. Profiting from recent developments in the determination of axial-vector transition form factors, short-distance constraints for the HLbL tensor, and the vector--vector--axial-vector correlator, we obtain \({a}_{\mu }^{\mathrm{HLbL}}=101.9(7.9)\times{}{10}^{- 11}\), which meets the precision requirements set by the final result of the Fermilab experiment.
Phys. Rev. Lett. 134, 061902 (2025)
Chiral perturbation theory, Nonperturbative effects in field theory, Perturbative QCD, Muons, Pions, Form factors, Magnetic moment, Real & complex analysis
Probing New Bosons and Nuclear Structure with Ytterbium Isotope Shifts
Research article | Atomic & molecular structure | 2025-02-11 05:00 EST
Menno Door et al.
In this Letter, we present mass-ratio measurements on highly charged \({\mathrm{Yb}}^{42+}\) ions with a precision of \(4\times{}{10}^{- 12}\) and isotope-shift measurements on \({\mathrm{Yb}}^{+}\) on the \({^{2}\mathrm{S}}_{1/2}\rightarrow ^{2}{\mathrm{D}}_{5/2}\) and \({^{2}\mathrm{S}}_{1/2}\rightarrow ^{2}{\mathrm{F}}_{7/2}\) transitions with a precision of \(4\times{}{10}^{- 9}\) for the isotopes \(^{168,170,172,174,176}\mathrm{Yb}\). We present a new method that allows us to extract higher-order changes in the nuclear charge distribution along the Yb isotope chain, benchmarking ab initio nuclear structure calculations. Additionally, we perform a King plot analysis to set bounds on a fifth force in the \(\mathrm{keV}/{c}^{2}\) to \(\mathrm{MeV}/{c}^{2}\) range coupling to electrons and neutrons.
Phys. Rev. Lett. 134, 063002 (2025)
Atomic & molecular structure, Atomic spectra, Electronic structure, Electronic transitions, Laser spectroscopy, Nuclear charge radii, Nuclear shapes and moments, Mass, Ab initio calculations, Mass spectrometry, Penning traps
Observation of Collapse and Revival in a Superconducting Atomic Frequency Comb
Research article | Circuit quantum electrodynamics | 2025-02-11 05:00 EST
E. S. Redchenko, M. Zens, M. Žemlička, M. Peruzzo, F. Hassani, R. Sett, P. Zieliński, H. S. Dhar, D. O. Krimer, S. Rotter, and J. M. Fink
Recent advancements in superconducting circuits have enabled the experimental study of collective behavior of precisely controlled intermediate-scale ensembles of qubits. In this work, we demonstrate an atomic frequency comb formed by individual artificial atoms strongly coupled to a single resonator mode. We observe periodic microwave pulses that originate from a single coherent excitation dynamically interacting with the multiqubit ensemble. We show that this revival dynamics emerges as a consequence of the constructive and periodic rephasing of the five superconducting qubits forming the vacuum Rabi split comb. In the future, similar devices could be used as a memory with in situ tunable storage time or as an on-chip periodic pulse generator with nonclassical photon statistics.
Phys. Rev. Lett. 134, 063601 (2025)
Circuit quantum electrodynamics, Frequency combs & self-phase locking, Quantum circuits, Quantum memories, Quantum networks, Quantum optics with artificial atoms, Quantum state transfer, Superconducting qubits
Theory of Electro-Ionic Perturbations at Supported Electrocatalyst Nanoparticles
Research article | Chemical kinetics, dynamics & catalysis | 2025-02-11 05:00 EST
Yufan Zhang, Tobias Binninger, Jun Huang, and Michael H. Eikerling
Nanoscopic heterogeneities in composition and structure are quintessential for the properties of electrocatalyst materials. Here, we present a semiclassical model to study the electrochemical properties of supported electrocatalyst nanoparticles (NP). The model captures the correlated electronic and ionic equilibration across NP, support, and electrolyte. It reveals peculiar trends in surface charging of the supported NP, validated by comparison with first-principles calculations. Support-induced perturbations in electronic and ionic charge densities at the NP's active surface manifest as distinct potentials of zero local electronic and ionic charges that could differ by more than 0.5 V in the studied system.
Phys. Rev. Lett. 134, 066201 (2025)
Chemical kinetics, dynamics & catalysis, Liquid-solid interfaces, Nanoparticles
Strain-Induced Enhancement of the Charge Density Wave in the Kagome Metal \(\mathrm{S}\mathrm{c}{\mathrm{V}}_{\mathrm{6}}{\mathrm{Sn}}_{6}\)
Research article | Charge order | 2025-02-11 05:00 EST
Manuel Tuniz, Armando Consiglio, Ganesh Pokharel, Fulvio Parmigiani, Titus Neupert, Ronny Thomale, Sandeep Kumar Chaluvadi, Pasquale Orgiani, Giorgio Sangiovanni, Stephen D. Wilson, Ivana Vobornik, Federico Salvador, Federico Cilento, Domenico Di Sante, and Federico Mazzola
The kagome geometry is an example of a frustrated configuration in which rich physics takes place, including the emergence of superconductivity and charge density wave (CDW). Among the kagome metals, \(\mathrm{S}\mathrm{c}{\mathrm{V}}_{\mathrm{6}}\mathrm{S}{\mathrm{n}}_{\mathrm{6}}\) hosts an unconventional CDW, with its electronic order showing a different periodicity from the leading lattice instability. In this material, a CDW-softened flat phonon band has a second-order collapse at the same time that the first-order transition occurs. This phonon band originates from the out-of-plane vibrations of the Sc and Sn atoms, and it is at the base of the electron-phonon-coupling driven CDW phase of \(\mathrm{S}\mathrm{c}{\mathrm{V}}_{\mathrm{6}}\mathrm{S}{\mathrm{n}}_{\mathrm{6}}\). Here we use uniaxial strain to tune the frequency of the CDW amplitude mode, which originates from the collapse of the flat phonon band, tracking its evolution via time-resolved optical spectroscopy and first-principles calculations. Our findings emphasize the capability to induce an enhancement of the unconventional CDW properties in \(\mathrm{S}\mathrm{c}{\mathrm{V}}_{\mathrm{6}}\mathrm{S}{\mathrm{n}}_{\mathrm{6}}\) kagome metal through control of strain.
Phys. Rev. Lett. 134, 066501 (2025)
Charge order, Electron-phonon coupling, Ultrafast pump-probe spectroscopy
Magnetic Phase Diagram of the Three-Dimensional Doped Hubbard Model
Research article | Magnetic phase transitions | 2025-02-11 05:00 EST
Liam Rampon, Fedor Šimkovic, IV, and Michel Ferrero
We establish the phase diagram of the Hubbard model on a cubic lattice for a wide range of temperatures, dopings, and interaction strengths, considering both commensurate and incommensurate magnetic orders. We use the dynamical mean-field theory together with an efficient method to compute the free energy which enable the determination of the correct ordering vectors. Besides an antiferromagnetic state close to half filling, we identify a number of different magnetic spiral phases with ordering vectors \((q,\pi ,\pi )\), \((q,q,\pi )\), and \((q,q,q)\), as well as a region with close competition between them, hinting at spatial phase separation or at the onset of a stripe phase. Additionally, we extensively study several thermodynamic properties with direct relevance to cold-atom experiments: the entropy, energy, and double occupancy.
Phys. Rev. Lett. 134, 066502 (2025)
Magnetic phase transitions, Spin density waves, Dynamical mean field theory, Hubbard model, Many-body techniques
Contractility-Driven Cell Motility against a Viscoelastic Resistance
Research article | Cell locomotion | 2025-02-11 05:00 EST
Tapas Singha and Pierre Sens
We study a model of contraction-based cell motility inside a microchannel to investigate the regulation of cell polarization and motion by the mechanical resistance of the environment. A positive feedback between the asymmetry of the acto-myosin cortex density and cell motion gives rise to spontaneous symmetry breaking and motility beyond a threshold contractility that depends on the resistance of extracellular medium. In highly viscous environments, we predict bistability under moderate contractility, so that symmetry breaking needs to be activated. In viscoelastic environments, we find the possibility for periodic oscillations in cortex density polarization and velocity. At the boundary between viscous and viscoelastic environments, the cell may cross, bounce back, or become trapped, depending on the viscoelastic relaxation time. These results are summarized in phase diagrams obtained by combining linear stability analysis and numerical simulations.
Phys. Rev. Lett. 134, 068401 (2025)
Cell locomotion, Cell mechanics, Cell migration, Living matter & active matter, Mechanobiology, Processes in cells, tissues & organoids
Physical Review X
Entanglement-Enhanced Atomic Gravimeter
Research article | Atom interferometry | 2025-02-11 05:00 EST
Christophe Cassens, Bernd Meyer-Hoppe, Ernst Rasel, and Carsten Klempt
The first measurement of gravity using quantum mechanically entangled atoms demonstrates the potential of the approach.
Phys. Rev. X 15, 011029 (2025)
Atom interferometry, Bose-Einstein condensates, Entanglement in quantum gases, Mach-Zehnder atom interferometry, Quantum entanglement, Quantum measurements, Quantum metrology, Quantum sensing, Quantum tomography, Spinor Bose-Einstein condensates
arXiv
Harnessing Artificial Intelligence for Modeling Amorphous and Amorphous Porous Palladium: A Deep Neural Network Approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Amorphous and amorphous porous palladium are key materials for catalysis, hydrogen storage, and functional applications, but their complex structures present computational challenges. This study employs a deep neural network trained on 33,310 atomic configurations from ab initio molecular dynamics simulations to model their interatomic potential. The AI-driven approach accurately predicts structural and thermal properties while significantly reducing computational costs. Validation against density functional theory confirms its reliability in reproducing forces, energies, and structural distributions. These findings highlight AI's potential in accelerating the study of amorphous materials and advancing their applications in energy and catalysis.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
8 pages, 4 figures
Accelerated Transition Rates in Generalized Kramers Problems for Non-Variational, Non-Normal System
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Virgile Troude, Didier Sornette
Kramers' escape problem serves as a paradigm for understanding transitions and various types of reactions, such as chemical and nuclear reactions, in systems driven by thermal fluctuations and damping, particularly within the realm of classical variational dynamics. Here, we generalize Kramers' problem to processes with non-normal dynamics characterized by asymmetry, hierarchy, and stochastic fluctuations, where transient amplification and stochastic perturbations play a critical role. The obtained generalized escape rates are structurally similar to those for variational systems, but with a renormalized temperature proportional to the square of the condition number k which measures non-normality. Because k can take large values (e.g., 10 r more) in many systems, the resulting acceleration of transition rates can be enormous, given the exponential dependence on the inverse temperature in Kramers' formula. We propose that non-normal accelerated escape rates are relevant to a wide range of systems, including biological metabolism, ecosystem shifts, climate dynamics, and socio-economic processes.
Statistical Mechanics (cond-mat.stat-mech)
main text of 5 pages and 7 pages of supplementary calculations
Origin of the Zeroth Law of Thermodynamics and its Role in Statistical Mechanics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
In statistical mechanics the zeroth law of thermodynamics is taken as a postulate which, as its name indicates, logically precedes the first and second laws. Treating it as a postulate has consequences for how temperature is introduced into statistical mechanics and for the molecular interpretation of temperature. One can, however, derive the zeroth law from first principles starting from a classical Hamiltonian using basic mechanics and a geometric representation of the phase space of kinetic energy configurations - the velocity hypersphere. In this approach there is no difficulty in providing a molecular interpretation of temperature, nor in deriving equality of temperature as the condition of thermal equilibrium. The approach to the macroscopic limit as a function of the number of atoms is easily determined. One also obtains with little difficulty the Boltzmann probability distribution, the statistical mechanical definition of entropy and the configuration partition function. These relations, along with the zeroth law, emerge as straightforward consequences of atoms in random motion.
Statistical Mechanics (cond-mat.stat-mech), Classical Physics (physics.class-ph)
23 pages, 3 figures
Anomalous suppression of large-scale density fluctuations in classical and quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Duyu Chen, Rhine Samajdar, Yang Jiao, Salvatore Torquato
Classical spin liquids (CSLs) are intriguing states of matter that do not exhibit long-range magnetic order and are characterized by an extensive ground-state degeneracy. Adding quantum fluctuations, which induce dynamics between these different classical ground states, can give rise to quantum spin liquids (QSLs). QSLs are highly entangled quantum phases of matter characterized by fascinating emergent properties, such as fractionalized excitations and topological order. One such exotic quantum liquid is the \(\mathbb{Z}_2\) QSL, which can be regarded as a resonating valence bond (RVB) state formed from superpositions of dimer coverings of an underlying lattice. In this work, we unveil a large-scale structural property of archetypal CSLs and QSLs known as hyperuniformity, i.e., normalized infinite-wavelength density fluctuations are completely suppressed in these systems. In particular, we first demonstrate that classical ensembles of close-packed dimers and their corresponding quantum RVB states are perfectly hyperuniform in general. Subsequently, we focus on a ruby-lattice spin liquid that was recently realized in a Rydberg-atom quantum simulator, and show that the QSL remains effectively hyperuniform even in the presence of a finite density of spinon and vison excitations, as long as the dimer constraint is still largely preserved. Moreover, we demonstrate that metrics based on the framework of hyperuniformity can be used to distinguish the QSL from other proximate quantum phases. These metrics can help identify potential QSL candidates, which can then be further analyzed using more advanced, computationally-intensive quantum numerics to confirm their status as true QSLs.
Strongly Correlated Electrons (cond-mat.str-el), Soft Condensed Matter (cond-mat.soft), Quantum Physics (quant-ph)
Proc. Natl. Acad. Sci. U.S.A., 122(6), e2416111122 (2025)
Structural Modulation and Enhanced Magnetic Ordering in Incommensurate K\(_{1-{x}}\)CrSe\(_2\) Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Felix Eder, Catherine Witteveen, Enrico Giannini, Fabian O. von Rohr
Layered delafossite-type compounds and related transition metal dichalcogenides, characterized by their triangular net structures, serve as prototypical systems for exploring the intricate interplay between crystal structure and magnetic behavior. Herein, we report on the discovery of the compound K\(_{1-x}\)CrSe\(_2\) (\(x \approx\) 0.13), an incommensurately modulated phase. Single crystals of this compound were grown for the first time using a K/Se self-flux. We find a monoclinic crystal structure with incommensurate modulation, that can be rationalized by a 3+1 dimensional model. This modulation compensates for the under-stoichiometry of K cations, creating pronounced undulations in the CrSe\(_2\) layers. Our anisotropic magnetization measurements reveal that K\(_{1-x}\)CrSe\(_2\) undergoes a transition to a long-range magnetically ordered state below \(T_{\mathrm N}\) = 133 K, a temperature 1.6 to 3.3 times higher than in earlier reported KCrSe\(_2\) compounds. Our findings open new avenues for tuning the magnetic properties of these layered materials through structural modulation.
Materials Science (cond-mat.mtrl-sci)
J. Am. Chem. Soc. 2025
Is attention all you need to solve the correlated electron problem?
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Max Geier, Khachatur Nazaryan, Timothy Zaklama, Liang Fu
The attention mechanism has transformed artificial intelligence research by its ability to learn relations between objects. In this work, we explore how a many-body wavefunction ansatz constructed from a large-parameter self-attention neural network can be used to solve the interacting electron problem in solids. By a systematic neural-network variational Monte Carlo study on a moiré quantum material, we demonstrate that the self-attention ansatz provides an accurate, efficient, and unbiased solution. Moreover, our numerical study finds that the required number of variational parameters scales roughly as \(N^2\) with the number of electrons, which opens a path towards efficient large-scale simulations.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Artificial Intelligence (cs.AI)
10+5 pages, comments welcome
Magnon-phonon interactions from first principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Khoa B. Le, Ali Esquembre-Kucukalic, Hsiao-Yi Chen, Ivan Maliyov, Jin-Jian Zhou, Davide Sangalli, Alejandro Molina-Sanchez, Marco Bernardi
Modeling spin-wave (magnon) dynamics in novel materials is important to advance spintronics and spin-based quantum technologies. The interactions between magnons and lattice vibrations (phonons) limit the length scale for magnon transport. However, quantifying these interactions remains challenging. Here we show many-body calculations of magnon-phonon (mag-ph) coupling based on the ab initio Bethe-Salpeter equation. We derive expressions for mag-ph coupling matrices and compute them in 2D ferromagnets, focusing on hydrogenated graphene and monolayer CrI3. Our analysis shows that electron-phonon (e-ph) and mag-ph interactions differ significantly, where modes with weak e-ph coupling can exhibit strong mag-ph coupling (and vice versa), and reveals which phonon modes couple more strongly with magnons. In both materials studied here, the inelastic magnon relaxation time is found to decrease abruptly above the threshold for emission of strongly coupled phonons, thereby defining a low-energy window for efficient magnon transport. By averaging in this window, we compute the temperature-dependent magnon mean-free path, a key figure of merit for spintronics, entirely from first principles. The theory and computational tools shown in this work enable studies of magnon interactions, scattering, and dynamics in generic materials, advancing the design of magnetic systems and magnon- and spin-based devices.
Materials Science (cond-mat.mtrl-sci)
Modular programming of interaction and geometric specificity enables assembly of complex DNA origami nanostructures
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Rupam Saha, Daichi Hayakawa, Thomas E. Videbaek, Mason Price, Wei-Shao Wei, Juanita Pombo, Daniel Duke, Gaurav Arya, Gregory M. Grason, W. Benjamin Rogers, Seth Fraden
We present a modular DNA origami design approach to address the challenges of assembling geometrically complex nanoscale structures, including those with nonuniform Gaussian curvature. This approach features a core structure that completely conserves the scaffold routing across different designs and preserves more than 70% of the DNA staples between designs, dramatically reducing both cost and effort, while enabling precise and independent programming of subunit interactions and binding angles through adjustable overhang lengths and sequences. Using cryogenic electron microscopy, gel electrophoresis, and coarse-grained molecular dynamics simulations, we validate a set of robust design rules. We demonstrate the method's utility by assembling a variety of self-limiting structures, including anisotropic shells with controlled inter-subunit interactions and curvature, and a toroid with globally varying curvature. Our strategy is both cost-effective and versatile, providing a promising and efficient solution for the synthetic fabrication of complex nanostructures.
Soft Condensed Matter (cond-mat.soft)
Main text 9 pages, 4 figures, SI 33 pages, 25 figures and 3 tables
Machine learning-guided construction of an analytic kinetic energy functional for orbital free density functional theory
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Sergei Manzhos, Johann Luder, Manabu Ihara
Machine learning (ML) of kinetic energy functionals (KEF) for orbital-free density functional theory (OF-DFT) holds the promise of addressing an important bottleneck in large-scale ab initio materials modeling where sufficiently accurate analytic KEFs are lacking. However, ML models are not as easily handled as analytic expressions; they need to be provided in the form of algorithms and associated data. Here, we bridge the two approaches and construct an analytic expression for a KEF guided by interpretative machine learning of crystal cell-averaged kinetic energy densities ({}) of several hundred materials. A previously published dataset including multiple phases of 433 unary, binary, and ternary compounds containing Li, Al, Mg, Si, As, Ga, Sb, Na, Sn, P, and In was used for training, including data at the equilibrium geometry as well as strained structures. A hybrid Gaussian process regression - neural network (GPR-NN) method was used to understand the type of functional dependence of {} on the features which contained cell-averaged terms of the 4th order gradient expansion and the product of the electron density and Kohn-Sham effective potential. Based on this analysis, an analytic model is constructed that can reproduce Kohn-Sham DFT energy-volume curves with sufficient accuracy (pronounced minima that are sufficiently close to the minima of the Kohn-Sham DFT-based curves and with sufficiently close curvatures) to enable structure optimizations and elastic response calculations.
Materials Science (cond-mat.mtrl-sci), Machine Learning (stat.ML)
16 pages, 5 figures
Magnetic transition in marcasite FeTe2 induced by the competition between crystal field splitting and Coulomb repulsion
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Yue-Fei Hou, Zhibin Shao, Minghu Pan, Shiyang Wu, Fawei Zheng, Zhen-Guo Fu, Ping Zhang
The determination of magnetic ground states in crystalline systems holds significant implications for both fundamental condensed matter physics and practical materials engineering. Marcasite-structured FeTe2, classified as a narrow-gap semiconductor, demonstrates anomalous magnetic behavior in low-temperature experimental investigations. This study employs first-principles density functional theory (DFT) calculations combined with scanning tunneling microscopy/spectroscopy (STM/STS) to elucidate the magnetic ground state of marcasite FeTe2. Our analysis reveals that the interplay between crystal field splitting and Coulomb repulsion critically governs the formation of localized magnetic moments in Fe ions. While bulk FeTe2 is conclusively identified as non-magnetic in its ground state, we demonstrate that the previously observed magnetic responses originate from surface-localized magnetic Fe atoms in FeTe2 specimens. This work establishes a robust yet straightforward criterion for determining ground-state magnetism across diverse localized electron systems, providing critical insights for interpreting magnetic phenomena in correlated electron materials.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
6 figures, 13 pages. Comments are welcome
Fabrication of self-powered photodetector materials based on Ni-doped ZnO/p-Si heterojunctions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Eka Nurfani, Aldi Saputra, Novalia Pertiwi, Muhamad F. Arif
In this paper, Ni-doped ZnO films were grown on a p-type silicon substrate via spray pyrolysis. The Ni dopant concentrations were varied by adjusting the weight ratio between Zinc Acetate Dehydrate (ZAD) and Nickel Chloride Hexahydrate (NCH), resulting in the ZnO, ZnO:Ni1%, and ZnO:Ni3% samples. Field-effect scanning electron microscopy (FESEM) images revealed that Ni doping significantly reduced the nanostructure size from 326 nm (ZnO) to 146 nm (ZnO:Ni3%). Similarly, X-ray diffraction (XRD) analysis also shows the decrease of the crystallite size with increasing Ni doping, from 44 nm (ZnO) to 35 nm (ZnO:Ni3%). Current-voltage (I-V) measurements were conducted at a bias voltage of 0 and 5 V to examine electrical and self-powered photodetection properties. All samples demonstrate self-powered photodetector performance. At the bias of 0 V, the undoped ZnO exhibited a higher photo-to-dark-current ratio (162) as compared to ZnO:Ni1% (18) and ZnO:Ni3% (16). The ZnO:Ni3% samples displayed faster rise (0.4 s) and fall times (1.7 s) as compared to the pure ZnO (10.8 s for rise time and 9.1 s for fall time), highlighting their potential for applications requiring rapid photoresponse. The findings provide valuable insights into optimizing the performance of ZnO-based photodetectors through controlled Ni doping, enabling advancements in self-powered photodetection technology for energy-efficient optoelectronic devices.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph)
Prospects for market-specific design of Perovskite-Silicon tandem solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Karthik Raitani, Pradeep R. Nair
The quest for optimal perovskite for tandem cell configurations is challenging as it involves several factors ranging from device level performance under field conditions to degradation rates and cost. Here, we first show that the traditional detailed balance or Shockley-Queisser (SQ) analysis leads to a stringent as well as unoptimized selection criteria for top cell perovskite. On the other hand, through detailed numerical simulations of the annual energy yield, well calibrated with recent temperature dependent experimental results, we identify geographic location-specific criteria for selecting optimal top cell perovskites. Our simulations indicate that, for certain degradation rates, a broad range of perovskite materials could yield comparable levelized cost of electricity (LCOE) - in contrast to the traditional detailed balance analysis. Our quantitative analysis shows that the optimal choice of perovskites indeed depends on the geographic location and relative degradation rate thus elucidating the prospects for market-specific design of P/Si tandem solar cells.
Materials Science (cond-mat.mtrl-sci)
Superconducting Properties of the Titanium-Based Oxides Compounds: A Review
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
In recent years, the superconductivity of novel layered materials, titanium-based pnictide oxides, was discovered. Due to the properties of possessing both cuprate and iron-based superconductors, these compounds have attracted the interest of researchers. Titanium pnictide oxides were reported to have CDW or SDW anomalies, theoretical calculations indicate that this DW behavior originates from the Ti2O layer. These compounds which have Ti2O layers provide a basis for studying the relationship between superconductivity and DW behavior. Superconductivity and DW behavior are two different electronic behaviors that typically compete with each other, but sometimes coexist. The relationship between them has always been a focus of condensed matter physics research. Through in-depth research on titanium-based superconductors, it may help us explain the unconventional superconducting transition phenomena present in iron-based superconductors. In this review, we introduce the latest research on titanium pnictide oxides and the electronic properties of these novel superconductors.
Superconductivity (cond-mat.supr-con)
Stark Shift from Quantum Defects in Hexagonal Boron Nitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Pei Li, Ran Xu, Bing Huang, Song Li
Color centers in hexagonal boron nitride have emerged as promising candidates for quantum information applications, owing to their efficient and bright single photon emission. Despite the challenges in directly characterizing these emitters, the interaction between external fields and defects, such as the Stark shift, offers valuable insights into their local geometric configurations. In this study, we focus on clarifying the possible origin of the distinct Stark shift characteristics observed experimentally, particularly in the emission range around 2 eV. We find that the local symmetry of the defects plays a crucial role in determining the nature of the Stark shift, which can be either linear or quadratic. Additionally, the local dielectric environment significantly influences the Stark shift response. Our calculations not only enhance the understanding of the micro-structure of these hitherto unknown emitters but also pave the way for their more effective utilization as single-photon sources and qubits in quantum technologies.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
7 pages, 4 figures
Preserving Twist-Angle in Marginally Twisted Double-Bilayer Graphene Devices During Fabrication
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Hyeon-Woo Jeong, Jiho Kim, Boknam Chae, Kenji Watanabe, Takashi Taniguchi, Gil-Ho Lee
Twisted van der Waals heterostructures provide a platform for studying a wide range of electron correlation phenomena, including unconventional superconductivity and correlated insulating states. However, fabricating such devices is challenging due to the difficulty in achieving and maintaining homogeneous twist-angles. Here, we present a fabrication method to preserve the twist-angle with minimal deformation. We fabricated marginally twisted double-bilayer graphene (mTDBG) stacks and directly imaged the resulting triangular superlattice periodicity via scattering-type scanning near-field optical microscopy (s-SNOM). This technique enabled us to monitor twist-angle deformation at each fabrication step, paving the way for more reliable device fabrication and facilitating the exploration of twist-angle-dependent physics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
15 pages, 4 figures
Quantum kinetic theory of semiclassical Boltzmann equation with side jump and skew scattering
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Da Ma, Zhi-Fan Zhang, Hua Jiang, X. C. Xie
The semiclassical Boltzmann equation is widely used to study transport effects. It is usually introduced in an intuitive fashion, which could cause confusion, e.g., over the collision integral with skew scattering. Actually, the Boltzmann equation is closely linked to the quantum density matrix, although term-by-term correspondence between the two is yet to be established. Here we start from the quantum Liouville equation in the interactive picture and show that the diagonal components of the equation yield the Boltzmann equation in homogeneous systems in an applied uniform electric field in the semiclassical limit, while the off-diagonal components give the anomalous velocity induced by Berry curvature and the side-jump velocity. The skew-scattering contribution is obtained when we include corrections beyond the first-Born approximation. The result derived from the denstiy matrix agrees with the semiclassical one from wave-packet analysis, showing that the semiclassical Boltzmann equation is more than an equation built from intuition, and it can be derived with the density matrix. Our work further clarifies the origin of the equation and eliminates the puzzles surrounding it.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Collective Hysteron Behavior in Nonlinear Flow Networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Lauren E. Altman, Nadia Awad, Douglas J. Durian, Miguel Ruiz-Garcia, Eleni Katifori
Multistability-induced hysteresis has been widely studied in mechanical systems, but such behavior has proven more difficult to reproduce experimentally in flow networks. Natural flow networks like animal and plant vasculature exhibit complex nonlinear behavior to facilitate fluid transport, so multistable flows may inform their functionality. To probe such phenomena in an analogous model system, we utilize an electronic network of hysterons designed to have tunable negative differential resistivity. We demonstrate our system's capability to generate complex global memory states in the form of voltage patterns. The tunable nonlinearity of each element's current-voltage characteristic allows us to navigate this space of hysteretic behavior, and can be utilized to engineer more complex networks with exotic effects such as avalanches and multiperiodic orbits.
Soft Condensed Matter (cond-mat.soft)
11 pages, 7 figures
Hyperparameter Optimization and Force Error Correction of Neuroevolution Potential for Predicting Thermal Conductivity of Wurtzite GaN
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Zhuo Chen, Yuejin Yuan, Wenyang Ding, Shouhang Li, Meng An, Gang Zhang
As a representative of wide-bandgap semiconductors, wurtzite gallium nitride (GaN) has been widely utilized in high-power devices due to high breakdown voltage and low specific on resistance. Accurate prediction of wurtzite GaN thermal conductivity is a prerequisite for designing effective thermal management systems of electronic applications. Machine learning driven molecular dynamics simulation offers a promising approach to predicting the thermal conductivity of large-scale systems without requiring predefined parameters. However, these methods often underestimate the thermal conductivity of materials with inherently high thermal conductivity due to the large predicted force error compared with first-principle calculation, posing a critical challenge for their broader application. In this study, we successfully developed a neuroevolution potential for wurtzite GaN and accurately predicted its thermal conductivity, 259 W/m-K at room temperatue, achieving excellent agreement with reported experimental measurements. The hyperparameters of neuroevolution potential (NEP) were optimized based on systematic analysis of reproduced energy and force, structural feature, computational efficiency. Furthermore, a force prediction error correction method was implemented, effectively reducing the error caused by the additional force noise in the Langevin thermostat by extrapolating to the zero-force error limit. This study provides valuable insights and hold significant implication for advancing efficient thermal management technologies in wide bandgap semiconductor devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 5 figures
Softening of Vibrational Modes and Anharmonicity Induced Thermal Conductivity Reduction in a-Si:H at High Temperatures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Zhuo Chen, Yuejin Yuan, Yanzhou Wang, Penghua Ying, Shouhang Li, Cheng Shao, Wenyang Ding, Gang Zhang, Meng An
Hydrogenated amorphous silicon (a-Si:H) has garnered considerable attention in the semiconductor industry, particularly for its use in solar cells and passivation layers for high performance silicon solar cells, owing to its exceptional photoelectric properties and scalable manufacturing processes. A comprehensive understanding of thermal transport mechanism in a-Si:H is essential for optimizing thermal management and ensuring the reliable operation of these devices. In this study, we developed a neuroevolution machine learning potential based on first-principles calculations of energy, forces, and virial, which enables accurate modeling of interatomic interactions in both a-Si:H and a-Si systems. Using the homogeneous nonequilibrium molecular dynamics (HNEMD) method, we systematically investigated the thermal conductivity of a-Si:H and a-Si across a temperature range of 300-1000 K and hydrogen concentrations ranging from 6 to 12 at%. Our simulation results found that thermal conductivity of a-Si:H with 12 at% hydrogen was significantly reduced by 12% compared to that of a-Si at 300 K. We analyzed the spectral thermal conductivity, vibrational density of states and lifetimes of vibrational modes, and revealed the softening of vibrational modes and anharmonicity effects contribute to the reduction of thermal conductivity as temperature and hydrogen concentration increase. Furthermore, the influence of hydrogen concentration and temperature on diffuson and propagon contribution to thermal conductivity of a-Si:H was revealed. This study provides valuable insights for developing thermal management strategies in silicon-based semiconducting devices and advances the understanding of thermal transport in amorphous systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 6 figures
Dynamics of Baxter-Wu model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Chen Tang, Wanzhou Zhang, Chengxiang Ding
Using Monte Carlo simulations, we investigated the dynamical properties of the Baxter-Wu model under linear quench. For the linear cooling process, the scaling behavior of the excess energy excitation density in the critical region aligns well with the predictions of the Kibble-Zurek (KZ) mechanism. However, the scaling behavior of the excess energy excitation density at the end of linear cooling does not conform to a simple interplay between the KZ mechanism and the coarsening process; after exiting the impulse regime, the system undergoes a decay close to a power-law form, with a decaying exponent that is significantly different from the coarsening exponent observed in instantaneous quenching. For the linear heating process, we found that if the initial state is the ground state of the model, the relevant exponents describing the KZ mechanism are identical to those in the cooling scenario. We find that the system does not directly enter the adiabatic regime after leaving the impulse regime but instead passes through a crossover regime with exponential decay of the excess energy excitation density. If the initial state is ordered but not the ground state of the system, the energy excitation density still exhibits good scaling behavior, but the relevant exponents do not conform to the predictions of the KZ mechanism. We found that this discrepancy is related to the peculiar zero-temperature dynamical properties arising from the unique ground states of the model.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 9 figures
Power-law decay of force on cell membrane tethers reflects long-ranged relaxation of membrane tension
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Emeline Laborie, Andrew Callan-Jones
Membrane tension is an acknowledged regulator of a wide array of cell functions; however, whether it acts locally or globally in different contexts remains debated. Recent experiments that locally perturb tension and measure the response elsewhere on the membrane are not conclusive, and the mechanism of diffusive tension relaxation has been called into doubt. Here, we consider the tension response to a sudden extension of a membrane tether, and report a quantitative signature of dynamic tension relaxation, which up to now is missing. We present a theory based on tension diffusion leading to a prediction of power-law decay in time of the force holding the tether, with a material-independent exponent of 1/3. This prediction is confirmed to within a few percent by re-analyzing eleven sets of tether data from two cell types with distinct membrane cortical architectures. Overall, our scaling results indicate the absence of a relevant characteristic length and therefore generically reflect tension relaxation by long-range membrane lipid flows.
Soft Condensed Matter (cond-mat.soft)
Engineered Chirality of One-Dimensional Nanowires
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Megan Briggeman, Elliott Mansfield, Johannes Kombe, François Damanet, Hyungwoo Lee, Yuhe Tang, Muqing Yu, Sayanwita Biswas, Jianan Li, Mengchen Huang, Chang-Beom Eom, Patrick Irvin, Andrew J. Daley, Jeremy Levy
The origin and function of chirality in DNA, proteins, and other building blocks of life represent a central question in biology. Observations of spin polarization and magnetization associated with electron transport through chiral molecules, known collectively as the chiral induced spin selectivity (CISS) effect, suggest that chirality improves electron transfer by inhibiting backscattering. Meanwhile, the role of coherence in the electron transport within chiral nanowires is believed to be important but is challenging to investigate experimentally. Using reconfigurable nanoscale control over conductivity at the LaAlO\(_3\)/SrTiO\(_3\) interface, we create chiral electron potentials that explicitly lack mirror symmetry. Quantum transport measurements on these chiral regions that constitute effective nanowires for the electrons reveal oscillatory transmission resonances as a function of both magnetic field and chemical potential. We interpret these resonances as arising from an engineered axial spin-orbit interaction within the chiral region. The ability to create 1D effective electron waveguides with this specificity and complexity creates new opportunities to test, via analog quantum simulation, theories about the relationship between chirality and spin-polarized electron transport in one-dimensional geometries.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Simulation study on Conservative Join (C-join) in Skyrmion Brownian circuit
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
H. Imanishi, E. Tamura, S. Miki, R. Ishikawa, H. Nomura, M. Goto, Y. Suzuki
Magnetic skyrmions, which exhibit Brownian motion in solid-state systems, are promising candidates as signal carriers for Brownian computing. However, successfully implementing such systems requires two critical components: a Hub to connect multiple wires and a C-join to synchronize the skyrmion signal carriers. While the former has been successfully addressed, the latter remains a significant challenge. In this study, we propose a novel solution by decomposing the C-join into two sub-circuits, the Join and Fork, and validate their functionality using a particle simulation approach. Our results demonstrate that the C-join can effectively synchronize skyrmion signals within 6.8{}s with a 99.9% success rate at low temperatures. Additionally, we construct the Half-adder in a crossing-free architecture utilizing the C-join circuits. These findings pave the way for the realization of skyrmion-based Brownian computing systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 6 figures
Dynamic Control of Third-order Nonlinear Optical Properties of Gold Nanoparticle/Liquid Crystal Composites under External Electric Fields
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Shengwei Wang, Mohamed Amine Gharbi, Chandra S Yelleswarapu
This study investigates the dynamic control of third-order nonlinear optical absorption properties of gold nanoparticles (AuNPs) dispersed in nematic liquid crystals (LC). By leveraging the reconfigurable nature of liquid crystals under external electric fields, we demonstrate the ability to manipulate AuNP alignment, dimer formation, and subsequently the plasmon coupling effects. Planar oriented and degenerate LC cells were prepared, and their optical responses under varying electric fields were characterized using polarization microscopy, UV-VIS spectroscopy, and Z-scan techniques. In planar cells, the applied electric field reorients LC molecules and AuNPs, influencing plasmon coupling and the nonlinear absorption. Conversely, degenerate cells exhibit more complex behaviors due to multiple LC alignment directions. These findings illustrate the potential of AuNP/nematic LC systems for creating tunable photonic devices responsive to external stimuli.
Soft Condensed Matter (cond-mat.soft), Optics (physics.optics)
16 pages, 10 figures
Altermagnetism in parallel-assembled single-atomic magnetic chains
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Deping Guo, Canbo Zong, Cong Wang, Weihan Zhang, Wei Ji
Altermagnetism has recently attracted significant interest in three- and two-dimensional materials, yet its realization in quasi-one-dimensional (Q1D) materials remains largely unexplored due to stringent symmetry constraints. Here, we systematically investigated the emergence of altermagnetism in 30 Q1D monolayer prototypes, self-assembled from intra-chain anti-ferrimagnetically coupled (XY_n) single-atomic magnetic chains, using symmetry analysis and high-throughput density functional theory calculations. Symmetry analysis identifies four structural prototypes capable of hosting altermagnetism, which expand to 192 monolayers upon materialization. Our calculations further reveal eight dynamically stable Q1D altermagnets, all belonging to the AA-stacked intra-chain AFM coupled ()-(XY_3) prototype, exhibiting (d)-wave-like spin splitting. Furthermore, we demonstrate the tunability of altermagnetic properties by varying inter-chain spacing and applying external electric fields. By optimizing these parameters, altermagnetism can be significantly enhanced, with spin splitting reaching several hundred meV in CoTe(_3), or substantially suppressed, leading to a transition to a nodal-line semiconducting state in CrCl(_3). These findings establish a diverse and highly tunable family of Q1D altermagnetic candidate materials.
Materials Science (cond-mat.mtrl-sci)
Ultrafast X-ray induced damage and nonthermal melting in cadmium sulfide
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Nikita Medvedev, Aldo Artímez Peña
Cadmium sulfide is a valuable material for solar cells, photovoltaic, and radiation detectors. It is thus important to evaluate the material damage mechanisms and damage threshold in response to irradiation. Here, we simulate the ultrafast XUV/X-ray irradiation of CdS with the combined model, XTANT-3. It accounts for nonequilibrium electronic and atomic dynamics, nonadiabatic coupling between the two systems, nonthermal melting and bond breaking due to electronic excitation. We find that the two phases of CdS, zinc blende and wurtzite, demonstrate very close damage threshold dose of ~0.4-0.5 eV/atom. The damage is mainly thermal, whereas with increase of the dose, nonthermal effects begin to dominate leading to nonthermal melting. The transient disordered state is a high-density liquid, which may be semiconducting or metallic depending on the dose. Later recrystallization may recover the material back to the crystalline phase, or at high doses create an amorphous phase with variable bandgap. The revealed effects may potentially allow for controllable tuning of the band gap via laser irradiation of CdS.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
Achieving electrode smoothing by controlling the nucleation phase of metal deposition through polymer-substrate binding
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Ying Xia, Duo Song, Mingyi Zhang, Zheming Wang, Chenyang Shi, Jingshan S. Du, Sun Hae Ra Shin, Mark H. Engelhard, Praveen K. Thallapally, Christine A. Orme, Jinhui Tao, Maria L. Sushko, James. J. De Yoreo, Jun Liu
Polymer additives [like polyethylene oxide (PEO)] are widely used for smooth electrode deposition in aqueous zinc and a number of other battery systems currently investigated for energy storage applications. However, the precise mechanism by which they regulate morphology and suppress dendrite formation remains unclear. In this study, we address this knowledge gap by using in-situ electrochemical atomic force microscopy (EC-AFM) to directly observe the interfacial evolution during Zn electrodeposition and polymer adsorption on copper (Cu) substrates in the presence of varying concentrations of ZnSO4 and PEO. Contrary to previous literature assumptions which emphasize the binding to the growing Zn crystal surfaces or Zn2+ ions, our results demonstrate that PEO smooths Zn films by promoting nucleation of (002)-oriented Zn platelets through interactions with the Cu substrate. Density functional theory (DFT) simulations support this finding by showing that PEO adsorption on Cu modifies the interfacial energy of Zn/Cu/electrolyte interfaces, favoring the stabilization of Zn (002) on the Cu substrate, as well as confines Zn electrodeposition to a narrow near-surface region. These findings elucidate a novel design principle for electrode smoothing, emphasizing the importance of substrate selection paired with polymer additives that exhibit an attractive interaction with the substrate, but minimal interaction with growing crystals, offering a mechanistic perspective for improved battery performance.
Materials Science (cond-mat.mtrl-sci)
Thoughts about boosting superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
In a superconductor electrons form pairs despite the Coulomb repulsion as a result of an effective attractive interaction mediated by, for example phonons. In the present paper DeGennes' description of the dynamically screened Coulomb interaction is adopted for the effective interaction. This model is generalized by including the elastic response of the charge-compensating background and the BCS gap equation is solved for the resulting effective electron-electron interaction. It is demonstrated that the superconducting critical temperature becomes strongly enhanced when the material is tuned close to a structural instability.
Superconductivity (cond-mat.supr-con)
7 pages, 3 figures
Topological doublon edge states induced by the spatially modulated interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Zheng-Wei Zuo, Wanwan Shi, Haisheng Li
The topological properties of the one-dimensional interacting systems with spatially modulated interaction in two-particle regime are theoretically investigated. Taking the boson-Hubbard model and spinless fermion interacting model as examples, we show that the energy spectra for doublon (known as two-particle pair) as a function of modulated period exhibit the butterfly-like structure for strongly-correlated limit, whose topological features can be decoded by the topological invariants and topological nontrivial doublon bound edge states. When the nearest-neighbor hopping evolves stronger, the doublon bands could intersect with scattering bands, the one-dimensional interacting systems display the phases of topological insulators and two-particle bound states in the continuum. For a sufficiently larger nearest-neighbor hopping, the doublon collapse takes place, where both the bulk doublon states and topological doublon edge states become unstable and could dissociate into two weakly interacting bosons. For the mapped two-dimensional single-particle systems, numerical calculations manifest the existence of the topological insulator and topological metal phases with corner states located in only one or two corners.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 5 figures
Vortices and antivortices in antiferroelectric PbZrO3
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Ying Liu, Huazhang Zhang, Konstantin Shapovalov, Ranming Niu, Julie M. Cairney, Xiaozhou Liao, Krystian Roleder, Andrzej Majchrowski, Jordi Arbiol, Philippe Ghosez, Gustau Catalan
Although ferroelectric materials are characterised by their parallel arrangement of electric dipoles, in the right boundary conditions these dipoles can reorganize themselves into vortices, antivortices and other non-trivial topological structures. By contrast, little is known about how (or whether) antiferroelectrics, which are materials showing an antiparallel arrangement of electric dipoles, can exhibit vortices or antivortices. In this study, using advanced aberration-corrected scanning transmission electron microscopy, we uncover the existence of atomic-scale (anti)vorticity in ferroelastic domain walls of the archetypal antiferroelectric phase of PbZrO3. The finding is supported, and its underlying physics is explained, using both second-principles simulations based on a deep-learning interatomic potential, and continuum field modelling. This discovery expands the field of chiral topologies into antiferroelectrics.
Materials Science (cond-mat.mtrl-sci)
10 pages/4 figures main paper, 31 pages total including supplementary information
Exact solution of the relationship between the eigenvalue discreteness and the behavior of eigenstates in Su-Schrieffer-Heeger lattices
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-11 20:00 EST
Huitong Wei, Xiumei Wang, Xingping Zhou
Eigenstate localization and bulk-boundary correspondence are fundamental phenomena in one-dimensional (1D) Su-Schrieffer-Heeger (SSH) lattices. The eigenvalues discreteness and the eigenstates localization exhibit a high degree of consistency as system information evolve. We explore the relationship between the eigenvalue discreteness and the eigenstates behavior in 1D SSH lattices. The discreteness fraction and the inverse participation ratio (IPR) combined with a Taylor expansion are utilized to describe the relationship. In the Hermitian case, we employ the bulk-edge correspondence and the perturbation theory to derive an exact solution considering both zero and non-zero modes. We also extend our analysis to the non-Hermitian cases, assuming that eigenvalues remain purely real. Our findings reveal a logarithmic relationship between the degree of eigenvalue discreteness and eigenstates localization, which holds under both the Hermitian and non-Hermitian conditions. This result is fully consistent with the theoretical predictions.
Other Condensed Matter (cond-mat.other)
submitted
The Importance of Pure Dephasing in the Optical Response of Excitons in High-quality van der Waals Heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Anabel Atash Kahlon, Matan Meshulam, Tomer Eini, Thomas Poirier, James H. Edgar, Seth Ariel Tongay, Itai Epstein
Excitons in monolayer transition metal dichalcogenides (TMDs) dominate their optical response due to exceptionally large binding energies arising from their two-dimensional nature. Several theoretical models have been proposed to describe this excitonic behavior, however, it remains unclear which model most accurately captures the underlying physical properties of the response. In this work, we experimentally measure the optical response of high-quality monolayer TMD heterostructures and compare the results with the different theoretical models to address this uncertainty. We find that in high-quality heterostructures, quantum mechanical interactions in the form of pure dephasing plays a dominant role, which has been challenging to isolate experimentally in previous studies. Furthermore, accounting for an additional decay rate to the commonly used radiative and non-radiative rates is found to be important for the accurate description of the excitonic response. These findings establish a robust framework for understanding and predicting the optical properties of TMD-based heterostructures, crucial for both fundamental research and optoelectronic applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
Enhanced collective vibrations in granular materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Shihori Koyama, Norihiro Oyama, Hideyuki Mizuno, Atsushi Ikeda
Granular materials are defined as collections of macroscopic dissipative particles. Although these systems are ubiquitous in our lives, the nature and the causes of their non-trivial collective dynamics still remain elusive and have attracted significant interest in non-equilibrium physics. Here, we focus on the vibrational dynamics of granular materials. While the vibrational dynamics of random packings have been examined concerning the jamming transition, previous research has overlooked the role of contact dissipations. We conducted numerical and analytical investigations into the vibrational dynamics of random packings influenced by the normal dissipative force, which is the simplest model for contact dissipations. Our findings reveal that the kinetic energy per mode diverges in the low-frequency range, following the scaling law \(\mathcal{K}_l \propto \omega^{-2}_l\) with the frequency \(\omega_l\), indicating that low-frequency modes experience strong excitation and that the equipartition of energy is violated. Additionally, the spatial structure factor of the velocity field displays the scaling law \(S_v(q) \propto q^{-2}\) with the wavenumber \(q\), which signifies that the velocity field has an infinitely long range. We demonstrate that these phenomena arise from the effects of weaker damping on softer modes, where the particle displacements parallel to the contacts are minimal in the low-frequency modes, rendering normal dissipation ineffective at dampening these modes.
Soft Condensed Matter (cond-mat.soft)
Visible-range excitons and electronic structure in \(d^0\) double perovskite oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Bhagyashree Behera, Debatri Ash, Urmimala Dey, M. K. Roy, Pritha Patra, K. Annapurna, S. K. Rout, Ajay K Himanshu, Rajyavardhan Ray
Presence of excitons significantly influence the optoelectronic properties and potential applications of materials. Using combined theoretical and experimental tools, we investigate the absorption spectra of \(d^0\) double perovskite oxides Ba\(_{2}\)Y\(B'\)O\(_6\) (\(B'\) = Nb, Ta, Sb), Ba\(_{2}\)Sc\(B'\)O\(_6\) (\(B'\) = Ta, Sb) and \(A_{2}\)ScSbO\(_6\) (\(A\)=Ca, Sr, Ba), allowing for a systematic variation of composition. We not only show that low-energy excitons are present in the visible range in {} the considered so-called wide-gap insulators, but also that the nature and properties of these exciton modes differ from those in double perovskite halides as well as perovskite oxides. We provide insights on the origin of such differences by a detailed and comparative analysis of the electronic structure. Further, our findings elucidate possible correlations between the exciton properties and the composition, via the electronic structure, towards a comprehensive understanding of correlation effects and rational design principles.
Materials Science (cond-mat.mtrl-sci)
9 pages, 4 figures
Microwave-regime demonstration of plasmonic non-reciprocity in a flowing two-dimensional electron gas
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Jingyee Chee, Han Sae Jung, Shannon Harvey, Kenneth West, Loren Pfeiffer, Amir Yacoby, Donhee Ham
The speed of a plasmonic wave in the presence of electron drift in a
conductor depends on the wave's propagation direction, with the wave
traveling along the drift
(forward wave') faster than the wave traveling against the drift (backward
wave'). Phenomena related to this plasmonic non-reciprocity -- which is
relatively more pronounced in two-dimensional conductors than in bulk
conductors and could lead to solid-state device applications -- have
been studied in THz and optical spectral regimes. Here we demonstrate
the plasmonic non-reciprocity at microwave frequencies (10 \(\sim\) 50 GHz). Concretely, we conduct, at
4K, a microwave network analysis on a gated GaAs two-dimensional
electron gas with electron drift (i.e., DC current), directly measuring
out forward and backward wave speeds via their propagation phase delays.
We resolve, for example, forward and backward wave speeds of \(4.26 \times 10^{-3} \pm 8.97 \times
10^{-6}\) (normalized to the speed of light). Sufficient
consistency between the electron drift speed obtained from the microwave
measurement and that alternatively estimated by a DC transport theory
further confirms the non-reciprocity. We conclude this paper with a
discussion on how to enhance the non-reciprocity for real-world
applications, where degeneracy pressure would play an important
role.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Higgs-mode-induced instability and kinetic inductance in strongly dc-biased dirty-limit superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
A perturbative ac field superposed on a dc bias (\(J_b\)) is known to excite the Higgs mode in superconductors. The dirty limit, where disorder enhances the Higgs resonance, provides an ideal setting for this study and is also relevant to many superconducting devices operating under strong dc biases. In this paper, we derive a general formula for the complex conductivity of disordered superconductors under an arbitrary dc bias using the Keldysh-Usadel theory of nonequilibrium superconductivity. This formula is relatively simple, making it more accessible to a broader research community. Our analysis reveals that in a strongly dc-biased dirty-limit superconductor, the Higgs mode induces an instability in the homogeneous superflow within a specific frequency window, making the high-current-carrying state vulnerable to ac perturbations. This instability, which occurs exclusively in the \({\rm ac} \parallel {\rm dc}\) configuration, leads to a non-monotonic dependence of kinetic inductance on frequency and bias strength. By carefully tuning the dc bias and the frequency of the ac perturbation, the kinetic inductance can be enhanced by nearly two orders of magnitude. In the weak dc bias regime, our formula recovers the well-known quadratic dependence, \(L_k \propto 1+ C(J_b/J_{\rm dp})^2\), with coefficients \(C=0.409\) for \({\rm ac} \parallel {\rm dc}\) and \(C=0.136\) for \({\rm ac} \perp {\rm dc}\), where \(J_{\rm dp}\) is the equilibrium depairing current density. These findings establish a robust theoretical framework for dc-biased superconducting systems and suggest that Higgs mode physics could be exploited in the design and optimization of superconducting detectors. Moreover, they may lead to a yet-to-be-explored detector concept based on Higgs mode physics.
Superconductivity (cond-mat.supr-con), Accelerator Physics (physics.acc-ph), Instrumentation and Detectors (physics.ins-det)
15 pages, 8 figures
High pressure structural and lattice dynamics study of α-In\(_2\)Se\(_3\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Shiyu Feng, Baihong Sun, Wenting Lu, Haikai Zou, Chenxin Wei, Qian Zhang, Bihan Wang, Martin Kunz, Hirokazu Kadobayashi, Azkar Saeed Ahmad, Elad Koren, Elissaios Stavrou
Layered \(\alpha\)-In\(_2\)Se\(_3\)has been studied using a concomitant in-situ synchrotron angle dispersive powder x-ray diffraction and Raman spectroscopy study in a diamond anvil cell up to 60+ GPa, at room temperature. Helium, that remains fairly hydrostatic up to the highest pressure in this study, was used as the pressure-transmitting medium. The results from both experimental methods reveal a pressure-induced structural phase transition from \(\alpha\)-In\(_2\)Se\(_3\) to a monoclinic \(\beta\)'-In2Se3 structure at $$1 GPa, in agreement with previous studies. Based on our detailed measurements using both experimental techniques and F-f formalism, the \(\beta\)'-In\(_2\)Se\(_3\) structure remains stable up to 45 GPa, without a clear indication of a phase transition towards the previously reported \(\beta\)-In2Se3 phase. Above this pressure, In\(_2\)Se\(_3\) adopts a disordered solid-solution-like orthorhombic structure, phase IV. The results are discussed in comparison with the relevant previous studies of \(\alpha\)-In\(_2\)Se\(_3\) under pressure.
Materials Science (cond-mat.mtrl-sci)
16 Pages, 6 figures
Giant Electro-Viscous Effects in Polar Fluids with Paraelectric-Modulated Antiferroelectric-Ferroelectric Phase Sequence
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Hiroya Nishikawa, Péter Salamon, Marcell Tibor Máthé, Antal Jákli, Fumito Araoka
The recently discovered ferroelectric nematic liquid-crystal material DIO exhibits an antiferroelectric (AF) phase, characterized by a sinusoidally modulated structure between the paraelectric (P) and ferroelectric (F) nematic phases. Although these sinusoidal modulated structures associated with the P-AF-F phase sequence is commonly observed in solid ferroelectrics, their presence in soft matter systems is scarce. This study is aimed at examining the macroscopic properties of DIO, identifying unique rheological properties, such as switching between shear thinning and shear thickening behaviors at certain shear rate in the ferroelectric nematic phase. Additionally, a significant electroviscous effect is observed, with the viscosity increasing by 70 times under an ultra-low electric field of 0.15 V um-1 at the AF-F transition.
Soft Condensed Matter (cond-mat.soft)
Main paper: 22 pages (6 figures); Supporting Information: 4 pages (3 figures)
Symmetry breaking in Prussian Blue Analogues via growth--guided local ordering of hexacyanometallate vacancies
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Yevheniia Kholina, Thomas Weber, Joohee Bang, Arthur Baroni, Marianne Liebi, Semen Gorfman, Ido Biran, Mark Warren, Dmitriy Chernyshov, Arkadiy Simonov
We report Growth--Guided Local Ordering, a novel mechanism of symmetry reduction in disordered crystals. This mechanism operates through the directional ordering of point defects during crystal growth, where defect correlations develop preferentially along the growth direction, resulting in reduced symmetry that persists in the final structure through the spatial distribution of defects. We demonstrate this phenomenon in Mn[Co]-Prussian Blue Analogues, disordered cyanide crystals containing numerous Co(CN)\(_6\) vacancies. Single crystal diffuse scattering reveals pronounced anisotropy in vacancy distribution: strong correlations along [001] growth direction contrast with weak correlations perpendicular to it. This local ordering reduces the Laue symmetry to tetragonal \(4/mmm\), evident in properties such as birefringence, while the average structure retains cubic \(m\bar 3m\) symmetry. When growth proceeds along [111] direction, the same mechanism produces domains with trigonal symmetry. Because this mechanism relies on fundamental aspects of crystal growth rather than specific material properties, it offers a general strategy for symmetry control in disordered crystals. Crucially, it transforms the complex task of altering crystal symmetry into the more manageable challenge of controlling growth direction, achievable through various established techniques such as the use of surfactants during crystallization.
Materials Science (cond-mat.mtrl-sci)
19 pages, 11 figures
Various Architectures of Colloidal Cu3(MoO4)2(OH)2 and Cu3Mo2O9; Thermal Stability, Photoluminescence and Magnetic Properties of Cu3(MoO4)2(OH)2 and Cu3Mo2O9 Nanosheets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Azam Bayat, Ali Reza Mahjoub, Mostafa M. Amini
The lindgrenite compounds [Cu3(MoO4)2(OH)2] with various architectures and high crystallinity were prepared by a simple surfactant-assisted hydrothermal method. Then, the Cu3Mo2O9 samples were prepared by calcination of the as-synthesized Cu3(MoO4)2(OH)2. The resulting samples have high crystallinity, colloidal properties, high-yield, large-scale production capability with using of nontoxic and inexpensive reagents and water as an environmentally solvent. The scanning electron microscope studies show that the as-prepared lindgrenite nanostructures are well crystallized with rod, sheet and hollow sphere morphologies. Meanwhile, the photoluminescence and magnetic properties of the nanosheet samples have been investigated that the both of Cu3(MoO4)2(OH)2 and Cu3Mo2O9 samples have super paramagnetic behavior at room temperature and in comparison with previous works, Cu3(MoO4)2(OH)2 and Cu3Mo2O9 samples synthesized by the surfactant-assisted hydrothermal method in this work have a very obvious red-shifted PL emission and high intensity.
Materials Science (cond-mat.mtrl-sci)
Electric field control of nonlinear Hall effect in Weyl semimetal TaIrTe4
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Jiaju Yang, Lujun Wei, Yanghui Li, Lina Chen, Wei Niu, Shuo Wang, Feng Li, Ping Liu, Shuang Zhou, Yong Pu
The nonlinear Hall effect (NLHE), as an important probe to reveal the symmetry breaking in topological properties of materials, opens up a new dimension for exploring the energy band structure and electron transport mechanism of quantum materials. Current studies mainly focus on the observation of material intrinsic the NLHE or inducing the NLHE response by artificially constructing corrugated/twisted twodimensionalmaterial systems. Notably, the modulation of NLHE signal strength, a core parameter of device performance, has attracted much attention, while theoretical predictions suggest that an applied electric field can achieve the NLHE enhancement through modulation of the Berry curvature dipole (BCD). Here we report effective modulation the magnitude and sign of the NLHE by applying additional constant electric fields of different directions and magnitudes in the semimetal TaIrTe4. The NLHE response strength is enhanced by 168 times compared to the intrinsic one at 4 K when the additional constant electric field of -0.5 kV/cm is applied to the b-axis of TaIrTe4 and the through a.c. current is parallel to the TaIrTe4 a-axis. Scaling law analysis suggests that the enhancement may be the result of the combined effect of the electric field on the intrinsic BCD and disorder scattering effect of TaIrTe4. This work provides a means to study the properties of TaIrTe4, as well as a valuable reference for the study of novel electronic devices.
Materials Science (cond-mat.mtrl-sci)
19 pages, 4 figures
Hopfield model with quasi-diagonal connection matrix
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-11 20:00 EST
We analyze a Hopfield neural network with a quasi-diagonal connection matrix. We use the term "quasi-diagonal matrix" to denote a matrix with all elements equal zero except the elements on the first super- and sub-diagonals of the principle diagonal. The nonzero elements are arbitrary real numbers. Such matrix generalizes the well-known connection matrix of the one dimensional Ising model with open boundary conditions where all nonzero elements equal +1. We present a simple description of the fixed points of the Hopfield neural network and their dependence on the matrix elements. The obtained results also allow us to analyze the cases of a) the nonzero elements constitute arbitrary super- and sub-diagonals and b) periodic boundary conditions.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
14 pages, 1 figure
Thermodynamic Cost of Steady State Erasure
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Deepak Gupta, Kristian Stølevik Olsen, Supriya Krishnamurthy
Recent experiments have implemented resetting by means of a time-varying external harmonic trap whereby the trap stiffness is changed from an initial to a final value in finite-time and then the system is reset when it relaxes to an equilibrium distribution in the final trap. Such setups are very similar to those studied in the context of the finite-time Landauer erasure principle. We analyse the thermodynamic costs of such a setup by deriving a moment generating function for the work cost of changing the trap stiffness in finite-time for a system in steady state. We analyse the mean and variance of the work required for a specific experimentally viable protocol and also obtain an optimal protocol which minimises the mean cost. For both these procedures, our analysis captures both the large-time and short-time corrections. For the optimal protocol, we obtain a closed form expression for the mean cost for all protocol durations, thereby making contact with earlier work on geometric measures of dissipation-minimising optimal protocols that implement information erasure.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
An ideal entropy transporter with finite power and vanishing fluctuation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Mingnan Ding, Jun Wu, Xiangjun Xing
We study a micro-magnet that interacts with a spin-polarized electric current, a heat bath, as well as a static magnetic field. The resulting non-equilibrium steady-state transports entropy between the current and the heat bath, without need of any thermodynamic force. In the limit of strong magnetic field, both the entropy production rate and the fluctuation of entropy transport become vanishingly small, whereas the average rate of entropy transport remains finite. Our results demonstrate that there is no fundamental limitation on the performance of thermodynamic engines other than the first and second laws of thermodynamics.
Statistical Mechanics (cond-mat.stat-mech)
Tailoring the normal and superconducting state properties of ternary scandium tellurides, Sc\(_6M\)Te\(_2\) ($M = $ Fe, Ru and Ir) through chemical substitution
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
J.N. Graham, K. Yuchi, V. Sazgari, A. Doll, C. Mielke III, P. Kral, O. Gerguri, S.S. Islam, V. Pomjakushin, M. Medarde, H. Luetkens, Y. Okamoto, Z. Guguchia
The pursuit of a unifying theory for non-BCS superconductivity has faced significant challenges. One approach to overcome such challenges is to perform systematic investigations into superconductors containing -electron metals in order to elucidate their underlying mechanisms. Recently, the Sc\(_6M\)Te\(_2\) (\(M\) = d-electron metal) family has emerged as a unique series of isostructural compounds exhibiting superconductivity across a range of \(3d\), \(4d\), and \(5d\) electron systems. In this study, we employ muon spin rotation, neutron diffraction, and magnetisation techniques to probe the normal and superconducting states at a microscopic level. Our findings reveal extremely dilute superfluid densities that correlate with the critical temperature (\(T_\mathrm{c}\)). Additionally, we identify high-temperature normal-state transitions that are inversely correlated with \(T_\mathrm{c}\). Notably, in Sc\(_6\)FeTe\(_2\), the superconducting pairing symmetry is most likely characterised by two nodeless gaps, one of which closes as electron correlations diminish in the Ru and Ir Sc\(_6M\)Te\(_2\) compounds. These results classify the Sc\(_6M\)Te\(_2\) compounds (\(M\) = Fe, Ru, Ir) as unconventional bulk superconductors, where the normal-state transitions and superconducting properties are governed by the interplay between electron correlations and spin-orbit coupling of the d-electron metal.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 10 figures
Allegro-FM: Towards Equivariant Foundation Model for Exascale Molecular Dynamics Simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Ken-ichi Nomura, Shinnosuke Hattori, Satoshi Ohmura, Ikumi Kanemasu, Kohei Shimamura, Nabankur Dasgupta, Aiichiro Nakano, Rajiv K. Kalia, Priya Vashishta
We present a foundation model for exascale molecular dynamics simulations by leveraging an E(3) equivariant network architecture (Allegro) and a set of large-scale organic and inorganic materials datasets merged by Total Energy Alignment (TEA) framework. Thanks to the large-scale training sets, the obtained model (Allegro-FM) is versatile for various materials simulations for diverse downstream tasks covering 89 elements in the periodic table. Allegro-FM exhibits excellent agreements with high-level quantum chemistry theories in describing structural, mechanical, and thermodynamic properties, while exhibiting emergent capabilities for structural correlations, reaction kinetics, mechanical strengths, fracture, and solid/liquid dissolution, for which the model has not been trained. Furthermore, we demonstrate the robust predictability and generalizability of Allegro-FM for chemical reactions using the transition1x that consists of 9.1 million transition state data, as well as calcium silicate hydrates as a testbed. With its computationally efficient, strictly-local network architecture, Allegro-FM scales up to multi-billion-atom systems with a parallel efficiency of 0.964 on the exaflop/s Aurora supercomputer at Argonne Leadership Computing Facility. The approach presented in this work demonstrates the potential of the foundation model for a novel materials design and discovery based on large-scale atomistic simulations.
Materials Science (cond-mat.mtrl-sci)
Effects of particle angularity on granular self-organization
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Dominik Krengel, Haoran Jiang, Takashi Matsushima, Raphael Blumenfeld
Recent studies of two-dimensional poly-disperse disc systems revealed a coordinated self-organisation of cell stresses and shapes, with certain distributions collapsing onto a master form for many processes, size distributions, friction coefficients, and cell orders. Here we examine the effects of grain angularity on the indicators of self-organisation, using simulations of bi-disperse regular \(N\)-polygons and varying \(N\) systematically. We find that: the strong correlation between local cell stresses and orientations, as well as the collapses of the conditional distributions of scaled cell stress ratios to a master Weibull form for all cell orders \(k\), are independent of angularity and friction coefficient. In contrast, increasing angularity makes the collapses of the conditional distributions sensitive to changes in the friction coefficient.
Soft Condensed Matter (cond-mat.soft)
12 pages, 10 figures; supplementary material 4 pages, 5 figures
Quantum Turbulence Across Dimensions: Crossover from two- to three-dimension
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
We investigate the dynamic transition of quantum turbulence (QT) in a confined potential field as the system evolves from purely two-dimensional (2D) to quasi-two-dimensional, and ultimately to three-dimensional (3D), by fixing the lateral dimensions of the trapping box while varying its height. In the 2DQT, distinct Onsager vortex cluster formation and inverse energy cascade are observed, while 3DQT exhibits a direct energy cascade consistent with the Vinen turbulence decay rate, which display striking differences. By systematically altering the system height, we explore how dimensionality drives the differentiation of turbulence types and find that this transition is closely related to the excitation of Kelvin waves. Kelvin waves not only introduce additional dissipation mechanisms but also serve as mediators for direct energy transfer across scales. When the wavelength of the permitted Kelvin waves exceeds the critical size of vortex clusters, turbulence begins transitioning to 3D type, culminating in fully developed 3DQT at the characteristic scale. In the transitional region, we observe continuous variations in the decay rate and vortex cluster correlation functions.
Quantum Gases (cond-mat.quant-gas), Fluid Dynamics (physics.flu-dyn), Quantum Physics (quant-ph)
6 pages, 5 figures
Universality and Crossovers for Quantum-Criticality in 2d metals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
A simple generalization of the theory of crossovers in classical-criticality to quantum-criticality gives that, a Heisenberg model with a small anisotropy favoring planar order has a cross-over towards the fixed point of the xy model in the temperature direction which is very rapid compared to those in the orthogonal directions, if the temporal correlation length is much larger than the spatial correlation length, i.e. for a large dynamic exponent \(z\). At the other end of the flow, the stability of the fixed point of the quantum xy model coupled to fermions is exponentially enhanced in the temperature direction. This is used to explain why the quantum-critical fluctuations of all measured 2d anti-ferromagnetic compounds - cuprates, heavy-fermion and Fe-based metals shows the characteristic fluctuations of the quantum xy model, and have the same anomalous transport and thermodynamic properties as the cuprates and twisted WSe\(_2\) and Graphene. We segue briefly to the range of extended quantum-criticality due to disorder by generalizing the Harris criteria as well, using the properties of the quantum xy model. The observed \(T \ln T\) specific heat at criticality is derived quite simply using the same methods which derive the cross-overs. This paper is written for the commemoration volume for Jan Zaanen whom I knew very well, starting from his days as a post-doc at Bell labs to his career as a distinguished Professor at Leiden.
Strongly Correlated Electrons (cond-mat.str-el)
Thermodynamic entropic uncertainty relation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Thermodynamic uncertainty relations reveal a fundamental trade-off between the precision of trajectory observables and entropy production, where the uncertainty in observables is quantified by their variance. In the context of information theory, uncertainty is often evaluated in terms of Shannon entropy, but it remains unclear whether there is a quantitative relation between Shannon entropy of the observables and entropy production in stochastic thermodynamics. In this Letter, we show that uncertainty relations can be formulated with observable Shannon entropy and entropy production. We introduce symmetry entropy, an entropy measure that quantifies the symmetry of the observable distribution, and demonstrate that a greater asymmetry in the observable distribution demands higher entropy production. This Letter elucidates the role of Shannon entropy of observables within stochastic thermodynamics, thereby establishing a foundation for deriving new uncertainty relations.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 3 figures
Identification of metastable lattice distortion free charge density wave at photoinduced interface via TRARPES
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Shaofeng Duan, Binshuo Zhang, Zihao Wang, Shichong Wang, Lingxiao Gu, Haoran Liu, Jiongyu Huang, Jianzhe Liu, Dong Qian, Yanfeng Guo, Wentao Zhang
The interplay between different degrees of freedom governs the emergence of correlated electronic states in quantum materials, with charge density waves (CDW) often coexisting with other exotic phases. Under thermal equilibrium, traditional CDW states are consequentially accompanied by structural phase transitions. In contrast, ultrafast photoexcitation allows access to exotic states where a single degree of freedom dominates in the time domain, enabling the study of underlying physics without interference. Here, we report the realization of a long-lived metastable CDW state without lattice distortion at the photoinduced interfaces in GdTe3 using time- and angle-resolved photoemission spectroscopy. After optical excitation above the CDW melting threshold, we identified emerged metastable interfaces through inverting the CDW-coupled lattice distortions, with lifetimes on the order of 10 picoseconds. These photoinduced interfaces represent a novel CDW state lacking the usual amplitude mode and lattice distortions, allowing quantification of the dominant role of electronic instabilities in CDW order. This work provides a new approach to disentangling electronic instabilities from electron-phonon coupling using a nonequilibrium method.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
26 Pages, 10 figures
npj Quantum Materials 10,16 (2025)
Enhanced diffusion over a periodic trap by hydrodynamic coupling to an elastic mode
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Juliette Lacherez (LOMA), Maxime Lavaud (LOMA), Yacine Amarouchene (LOMA), David S. Dean (LOMA), Thomas Salez (LOMA)
In many physical systems, degrees of freedom are coupled hydrodynamic forces, even in the absence of Hamiltonian interactions. A particularly important and widespread example concerns the transport of microscopic particles in fluids near deformable boundaries. In such a situation, the influence of elastohydrodynamic couplings on Brownian motion remains to be understood. Unfortunately, the temporal and spatial scales associated with the thermal fluctuations of usual surfaces are often so small that their deformations are difficult to monitor experimentally, together with the much slower and larger particle motion at stake. Here, we propose a minimal model describing the hydrodynamic coupling of a colloidal particle to a fluctuating elastic mode, in presence of an external periodic potential. We demonstrate that the late-time diffusion coefficient of the particle increases with the compliance of the elastic mode. Remarkably, our results reveal that, and quantify how: i) spontaneous microscopic transport in complex environnements can be affected by soft boundaries -- a situation with numerous practical implications in nanoscale and biological physics; ii) the effects of fast and tiny surface deformations are imprinted over the long-term and large-distance colloidal mobility -- and are hence measurable in practice.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
Investigation of Fe-Ag and Ag-Fe Interfaces in Ag-57Fe-Ag trilayer Using Nuclear Resonance Scattering under X-ray Standing Wave Conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Manisha Priyadarsini, Sharanjeet Singh, Ilya Sergeev, Olaf Leupold, Ajay Gupta, Dileep Kumar
Understanding the interfaces of layered nanostructures is key to optimizing their structural and magnetic properties for the desired functionality. In the present work, the two interfaces of a few nm thick Fe layer in Ag-57Fe-Ag trilayers are studied with a depth resolution of a fraction of a nanometer using x-ray standing waves (XSWs) generated by an underlying [W-Si]x10 multilayer (MLT) at an x-ray incident angle around the Bragg peak of the MLT. Interface selectivity in Ag-57Fe-Ag trilayers was achieved by moving XSW antinodes across the interfaces by optimizing suitable incident angles and performing depth-resolved nuclear resonance scattering (NRS) and X-ray fluorescence (XRF) measurements for magnetic and structural properties. The combined analysis revealed that the rms roughness of 57Fe-on-Ag and Ag-on-57Fe interfaces are not equal. The roughness of the 57Fe-on-Ag interface is 10 Angstrom, while that of the Ag-on-57Fe interface is 6 Angstrom. 57Fe isotope sensitive NRS revealed that hyperfine field (HFF) at both interfaces of 57Fe-on-Ag and Ag-on-57Fe interfaces are distinct, which is consistent with the difference in interface roughnesses measured as root mean square (RMS) roughness. Thermal annealing induces 57Fe diffusion into the Ag layer, and annealing at 325 C transforms the sample into a paramagnetic state. This behavior is attributed to forming 57Fe nanoparticles within the Ag matrix, exhibiting a paramagnetic nature. These findings provide deep insights into interface properties crucial for developing advanced nanostructures and spintronic devices.
Materials Science (cond-mat.mtrl-sci)
17 pages, 5 figures
Nonanalytic Landau functionals shaping the finite-size scaling of fluctuations and response functions in and out of equilibrium
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Krzysztof Ptaszynski, Massimiliano Esposito
Landau theory relates phase transitions to the minimization of the Landau functional (e.g., free energy functional), which is expressed as a power series of the order parameter. It has been shown that the critical behavior of certain physical systems can be described using Landau functionals that include nonanalytic terms, corresponding to odd or even noninteger powers of the absolute value of the order parameter. In particular, these nonanalytic terms can determine the order of the phase transition and the values of the critical exponents. Here, we show that such terms can also shape the finite-size scaling behavior of fluctuations of observables (e.g., of energy or magnetization) or the response functions (e.g., heat capacity or magnetic susceptibility) at the continuous phase transition point. We demonstrate this on two examples, the equilibrium molecular zipper and the nonequilibrium version of the Curie--Weiss model.
Statistical Mechanics (cond-mat.stat-mech)
9 pages, 8 figures
Observation of a \(Pbca\) phase and robust metallicity in \(\rm{RuO_2}\) under pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
He Zhang, Xudong Wei, Wei Zhong, Xiaoli Ma, Liyunxiao Wu, Jie Zhou, Saori Kawaguchi, Hirokazu Kadobayashi, Zhenxiang Cheng, Guoying Gao, Xiaohui Yu, Ho-kwang Mao, Binbin Yue, Fang Hong
\(\rm{RuO_2}\) stands as a quintessential rutile-type compound under ambient conditions, with its structural exploration under pressure bearing significant implications for both phase transition investigations and Earth science. Nonetheless, the precise phase transition sequence remains a debate. In this study, we disclose the emergence of the \(Pbca\) phase alongside the enduring metallic character of \(\rm{RuO_2}\) under megabar pressure. Employing state-of-the-art synchrotron X-ray diffraction, our observations delineate a phase transition trajectory progressing through rutile, \(\rm{CaCl_2}\), and ultimately \(Pbca\) phases. Notably, the \(Pbca\) phase manifests immediately just after the rutile-\(\rm{CaCl_2}\) transition, confining a narrow pressure regime for the pure \(\rm{CaCl_2}\)-type phase. Within the pressure range of 15.5 to 35.0 GPa, a coexistence of the \(\rm{CaCl_2}\)-type and \(Pbca\) phases is observed, transforming to a sole presence of the \(Pbca\) phase beyond 35.0 GPa. Electrical transport measurements conducted on both single crystal and powder samples confirm the enduring metallic conductivity of \(\rm{RuO_2}\), persisting up to at least $$120 GPa, albeit exhibiting a diminished conductivity at ultrahigh pressures due to a reduction in electronic density of states at the Fermi level. This study furnishes compelling evidence for the presence of the \(Pbca\) phase across a broad pressure range, diverging from the previously widely acknowledged \(Pa\bar{3}\) phase, thereby offering crucial insights into phase transition phenomena in other metal dioxides and advancing our comprehension of electronic behaviors within 4d and 5d electron systems.
Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures
Unveiling Optimal Diffusion for Infection Control in Brownian Particle Systems
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-11 20:00 EST
Kaito Takahashi, Makiko Sasada, Takuma Akimoto
Understanding the spread of infectious diseases requires integrating movement and interaction dynamics into epidemiological models. In this study, we investigate the role of particle diffusivity and physical constraints in shaping infection dynamics within a system of Brownian particles. Through numerical simulations and theoretical analyses, we uncover a nontrivial relationship between diffusivity and infection speed: an optimal diffusion coefficient exists that minimizes the infection spreading speed. This counterintuitive result arises from a balance between particle mixing and interaction frequency. The optimal diffusivity is observed in both interacting and non-interacting systems when the infection radius exceeds the mean lattice spacing and the initial configuration is out of equilibrium. Our findings provide a theoretical framework for understanding and controlling the spread of infections in confined and diffusive environments, with potential implications for designing movement-based strategies for infection control.
Other Condensed Matter (cond-mat.other)
10 pages, 5 figures
Self-organized criticality driven by droplet influx and random fusion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
The droplet size distribution typically decays exponentially in solutions formed by liquid-liquid phase separation. Nevertheless, a power-law distribution of nucleoli volumes has been observed in amphibian oocytes, which appears similar to the cluster size distribution in reaction-limited aggregation. In this work, we study the mechanism of power-law distributed droplet sizes and unveil a self-organized criticality driven by droplet influx and random fusion between droplets. Surprisingly, the droplet size dynamics is governed by a similar Smoluchowski equation as the cluster size in aggregation systems. The system reaches a critical state as the area fraction approaches the critical value at which the droplet size has a power-law distribution with a \(1.5\) exponent. Furthermore, the system is also spatially scale-free with a divergent correlation length at the critical state, marked by giant droplet-density fluctuations and power-law decay of the pair correlation function.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Even denominator fractional quantum Hall states in the zeroth Landau level of monolayer-like band of ABA trilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Tanima Chanda, Simrandeep Kaur, Harsimran Singh, Kenji Watanabe, Takashi Taniguchi, Manish Jain, Udit Khanna, Ajit C. Balram, Aveek Bid
The fractional quantum Hall (FQH) effect is a macroscopic manifestation of strong electron-electron interactions. Even denominator FQH states (FQHSs) at half-filling are particularly interesting as they are predicted to host non-Abelian excitations with non-trivial braiding statistics. Such states are predominantly observed in the \(N=1\) Landau level (LL) of semiconductors such as GaAs. In this Letter, we report the unanticipated observation of even-denominator FQHSs in the \(N=0\) LL of ABA trilayer graphene (TLG), a system characterized by tunable LL mixing and the absence of inversion symmetry. Notably, we find robust FQHSs at \(\nu=5/2\) and \(\nu=7/2\) when two LLs, originating from a monolayer-like band of TLG with different isospin indices, cross each other. These are flanked by the Levin-Halperin daughter states at \(\nu=7/13\) and \(\nu=9/17\), respectively, and further away, the standard series of Jain-sequence of composite fermions (CFs) is observed. The even-denominator FQHSs and their accompanying daughter states become stronger with increasing magnetic fields, while concomitantly, a weakening of the CF states is observed. We posit that the absence of inversion symmetry in the system gives rise to additional isospin interactions, which enhance LL mixing and soften the short-range part of the Coulomb repulsion, stabilizing the even-denominator FQHSs. In addition, we demonstrate that these states, along with their daughter states, can be finely tuned with an external displacement field that serves as an important tool to control the LL mixing in the system.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
24 pages, comments and suggestions are very welcome
Observation of Coherent Quantum Tunneling of a Massive Atomic Cluster with 435 u
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Han Zhang, Yong-Kui Wang, Yi Zheng, Hai-Tao Bai, Bing Yang
Tunneling is a genuine quantum phenomenon typically observed in low-mass particles such as electrons. However, it fades rapidly as mass increases due to the exponential decay of the matter-wave penetration depth. Cooling atoms to nanokelvin temperatures enhances their matter wave characteristics. Here, we report the observation of coherent quantum tunneling of a bonded cluster composed of 5 ultracold rubidium-87 atoms, collectively forming a massive object of 435 u. Using a double-well superlattice, integer occupancy states are prepared, with atoms bonded via strong on-site interactions. We demonstrate that the exponential base of tunneling strength can be tuned to approach unity, drastically reducing its decay for heavier masses and enabling a scalable strategy. Moreover, tunneling is harnessed to create spatially separated Schrödinger-cat states (~320 nm apart), achieving quantum enhancement in measurements. This work markedly raises the mass threshold for quantum tunneling and paves the way for quantum metrology with massive particles.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
15 pages, 11 figures
Dynamical Spreading Under Power Law Potential
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Ido Fanto, Yuval Rosenblum, Ori Harel, Naomi Oppenheimer
We investigate the dynamic spreading of a dense suspension of particles under power law repulsive potentials decaying as \(1/r^k\). We find analytically that the particles spread in a self-similar form, where the radius grows with time as \(t^{1/(k+2)}\). Our results closely align with experiments of paramagnetic colloidal particles under an external magnetic field interacting via a \(1/r^3\) potential. We further substantiate the theory by molecular dynamic simulations of thousands of particles in one and two dimensions. The simulations reveal a rich diversity of behaviors contingent on the value of \(k\). Specifically, for \(k>D-2\) (where \(D\) is the dimension), the density is centered in the middle, for \(k = D-2\), density is uniform, and for \(k<D-2\), there is an aggregation of particles at the edge of the suspension. When two or more such suspensions are placed near each other, the system retains a power-law memory of its initial state, resulting in a particle-free zone at the interface of the merging populations.
Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
arXiv admin note: text overlap with arXiv:2501.05846
Chiral Raman coupling for spin-orbit coupling in ultracold atomic gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Biao Shan, Lianghui Huang, Yuhang Zhao, Guoqi Bian, Pengjun Wang, Wei Han, Jing Zhang
Spin-orbit coupling (SOC) in ultracold atoms is engineered by light-atom interaction, such as two-photon Raman transitions between two Zeeman spin states. In this work, we propose and experimentally realize chiral Raman coupling to generate SOC in ultracold atomic gases, which exhibits high quantization axis direction-dependence. Chiral Raman coupling for SOC is created by chiral light-atom interaction, in which a circularly polarized electromagnetic field generated by two Raman lasers interacts with two Zeeman spin states \(\delta m_{F}=\pm 1\) (chiral transition). We present a simple scheme of chiral one-dimension (1D) Raman coupling by employing two Raman lasers at an intersecting angle 90\(^{\circ}\) with the proper polarization configuration. In this case, Raman coupling for SOC exist in one direction of the magnetic quantization axis and disappears in the opposite direction. Then we extend this scheme into a chiral 2D optical square Raman lattice configuration to generate the 1D SOC. There are two orthogonal 1D SOC, which exists in the positive and negative directions of the magnetic quantization axis respectively. This case is compared with 2D SOC based on the nonchiral 2D optical Raman lattice scheme for studying the topological energy band. This work broadens the horizon for understanding chiral physics and simulating topological quantum systems.
Quantum Gases (cond-mat.quant-gas)
Transmission through rectangular potentials in semimetals featuring quadratic dispersion
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
We revisit the problem of transmission of quasiparticles through a rectangular potential barrier for semimetals featuring quadratic-in-momentum band-crossings at a nodal point. Although this was considered in Annals of Physics 419 (2020) 168235, the solutions corresponding to evanescent waves were missed, leading to a partial fulfillment of the boundary conditions required to determine the piecewise-continuous wavefunctions. In this paper, our aim is to correct those shortcomings, recompute the transmission coefficients, and show the resulting behaviour of the conductivity and the Fano factor for some representative parameter values.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
corrects the solutions shown in arXiv:2004.06134 by incorporating the missing evanescent waves
Fermion mediated pairing in the Ruderman-Kittel-Kasuya-Yosida to Efimov transition regime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Geyue Cai, Henry Ando, Sarah McCusker, Cheng Chin
The Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction and Efimov physics are two distinct quantum phenomena in condensed matter and nuclear physics, respectively. The RKKY interaction describes correlations between impurities mediated by an electron gas, while Efimov physics describes universal bound states of three particles with resonant interactions. Recently, both effects have been observed in Bose-Fermi mixtures in the weak and resonant interaction regimes, respectively. Intriguing conjectures exist to elucidate how the two phenomena meet in the transition regime where the mixture is strongly interacting. In this work, we explore the RKKY-Efimov transition in a mixture of bosonic Cs-133 and fermionic Li-6 near a tunable interspecies Feshbach resonance. From dispersion and relaxation measurements, we find that the transition is highlighted by a fermion-mediated scattering resonance between Cs atoms and a weaker resonance on Li atoms. These resonances represent reactive scattering of Cs and Li atoms in the many-body regime, which reduces to an Efimov resonance in the thermal gas regime. Our observation demonstrates the intriguing interplay of two-, three-, and many-body physics in an Bose-Fermi mixture that connects condensed matter physics, nuclear physics and quantum many-body chemistry.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
Rheologically tuned modes of collective transport in active viscoelastic films
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Henning Reinken, Andreas M. Menzel
While many living biological media combine both viscous and elastic properties, most theoretical studies employ either purely fluid- or solid-like descriptions. We here use a unified framework for active films on substrates capable of describing a broad range of viscoelastic behavior to explore the interplay between activity and rheology. The core of the study is a comprehensive state diagram showing a rich world of spatiotemporal dynamic states. Our results demonstrate the potential of tunable rheology to realize modes of controlled active transport on the microscale.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Fluid Dynamics (physics.flu-dyn)
Dynamics and clustering of sedimenting disc lattices
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Harshit Joshi, Rahul Chajwa, Sriram Ramaswamy, Narayanan Menon, Rama Govindarajan
Uniform arrays of particles tend to cluster as they sediment in viscous fluids. Shape anisotropy of the particles enriches these dynamics by modifying the mode-structure and the resulting instabilities of the array. A one-dimensional lattice of sedimenting spheroids in the Stokesian regime displays either an exponential or an algebraic rate of clustering depending on the initial lattice spacing (Chajwa et al. 2020). This is caused by an interplay between the Crowley mechanism which promotes clumping, and a shape-induced drift mechanism which subdues it. We theoretically and experimentally investigate the sedimentation dynamics of one-dimensional lattices of oblate spheroids or discs and show a stark difference in clustering behaviour: the Crowley mechanism results in clumps comprised of several spheroids, whereas the drift mechanism results in pairs of spheroids whose asymptotic behavior is determined by pair-hydrodynamic interactions. We find that a Stokeslet, or point-particle, approximation is insufficient to accurately describe the instability and that the corrections provided by the first-reflection are necessary for obtaining some crucial dynamical features. As opposed to a sharp boundary between exponential growth and neutral eigenvalues under the Stokeslet approximation, the first-reflection correction leads to exponential growth for all initial perturbations, but far more rapid algebraic growth than exponential growth at large lattice spacing \(d\). For discs with aspect ratio 0.125, corresponding to the experimental value, the instability growth rate is found to decrease with increasing lattice spacing \(d\), approximately as \(d^{-4.5}\), which is faster than the \(d^{-2}\) for spheres (Crowley, 1971). Sedimenting pairs predominantly come together to form '\(\perp\)', which our theory accounts for through an analysis that builds on Koch & Shaqfeh (1989).
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
22 pages, 15 figures. Under consideration for publication in J. Fluid Mech
Oscillatory collective motion in viscoelastic and elastic active fluids and solids under circular confinement
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-11 20:00 EST
Henning Reinken, Andreas M. Menzel
In an inspiring recent study, Xu et al. [Nat. Phys. 19, 46 (2023)] observed for a living active biofilm under circular confinement two emergent dynamic modes of collective motion in the film. One corresponds to global rotational motion of oscillating sense of rotation, the other one to uniformly translating motion of rotating migration direction. The authors reproduced these features in a discretized theoretical model for elastic active solids. We here demonstrate that the discovered fundamental phenomena are generic and emerge abundantly for a broad range of viscoelastic fluids and solids. Elastic solids represent only one limiting case.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Fluid Dynamics (physics.flu-dyn)
A physics-based data-driven model for CO\(_2\) gas diffusion electrodes to drive automated laboratories
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Ivan Grega, Félix Therrien, Abhishek Soni, Karry Ocean, Kevan Dettelbach, Ribwar Ahmadi, Mehrdad Mokhtari, Curtis P. Berlinguette, Yoshua Bengio
The electrochemical reduction of atmospheric CO\(_2\) into high-energy molecules with renewable energy is a promising avenue for energy storage that can take advantage of existing infrastructure especially in areas where sustainable alternatives to fossil fuels do not exist. Automated laboratories are currently being developed and used to optimize the composition and operating conditions of gas diffusion electrodes (GDEs), the device in which this reaction takes place. Improving the efficiency of GDEs is crucial for this technology to become viable. Here we present a modeling framework to efficiently explore the high-dimensional parameter space of GDE designs in an active learning context. At the core of the framework is an uncertainty-aware physics model calibrated with experimental data. The model has the flexibility to capture various input parameter spaces and any carbon products which can be modeled with Tafel kinetics. It is interpretable, and a Gaussian process layer can capture deviations of real data from the function space of the physical model itself. We deploy the model in a simulated active learning setup with real electrochemical data gathered by the AdaCarbon automated laboratory and show that it can be used to efficiently traverse the multi-dimensional parameter space.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
7 pages, 5 figures. Submitted to AI4Mat-ICLR2025 workshop
Engineering of electronic and magnetic modulations in gradient functional oxide heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Leonard Schüler, Yannik Sievert, Vladimir Roddatis, Ulrich Ross, Vasily Moshnyaga, Fryderyk Lyzwa
Advanced interface engineering provides a way to control the ground state of correlated oxide heterostructures, which enables the shaping of future electronic and magnetic nanodevices with enhanced performance. An especially promising and rather new avenue is to find and explore low-dimensional phases of structural, ferroic and superconducting origin. In this multimodal study, we present a novel dynamic growth control method that enables synthesizing compositionally graded superlattices (SLs) of (LaMnO_3)_10/(SrMnO_3)_10 (LMO/SMO), in which the layers gradually change their composition between LMO and SMO with gradient G values ranging from 0 to 100 %. This leads to strong modulations in the material's electronic properties and of the two-phase ferromagnetic (FM) behavior. In particular, we observe that G has almost no impact on the emergent high-temperature FM phase; in contrast, the low-temperature volume-like FM phase increases drastically with higher G-factors and thus can serve as a precise marker for chemical composition on a nanoscale. Focusing on the interfacial charge transfer found at sharp SMO/LMO interfaces (G=0), we observe that for higher G-factors a long-range charge modulation develops, which is accompanied by an insulator-to-metal transition. These findings showcase G as a crucial control parameter that can shape the superlattice's intrinsic properties and provide a perspective for designing functional oxide heterostructures with artificially disordered interfaces.
Materials Science (cond-mat.mtrl-sci)
20 pages, 8 figures
Flat-Band Driven Kondo Breakdown and Reentrant Effects in Heavy-Fermion Moiré Superlattices
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Fabian Eickhoff, Jian-Xin Zhu, Benedikt Fauseweh
Moiré superlattices (MSLs) in van der Waals (vdW) heterostructures have demonstrated their incredible power in driving emergent electronic phenomena, some of which are reminiscent of those usually only observed in bulk strongly correlated quantum materials. With the recent discovery of van der Waals \(f\)-electron materials, the design of novel MSLs of intrinsic strong correlation is now within the reach. Here we study the novel electron phases of two-dimensional heavy-fermion MSL with increasingly diluted f-electron local moments. By applying dynamical mean field theory (DMFT) with numerical renormalization group (NRG) as an impurity solver, we demonstrate the appearance of a new energy scale and a re-entrant Kondo breakdown in connection with the emergence of a flat band in the system. We further compare our numerical findings with predictions derived from the Lieb-Mattis theorem and show the necessity of the new energy scale to consistently reconcile the predictions with the conventional single-impurity limit for exceedingly large unit cells.
Strongly Correlated Electrons (cond-mat.str-el)
The First Principles Equation for Coherent Phonons: Dynamics and Polaron distortions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Gianluca Stefanucci, Enrico Perfetto
This paper addresses the first principles description of coherent phonons in systems subjected to optical excitations and/or doping. We reformulate the first-principles Ehrenfest equation (fpEE) [Phys. Rev. X {}, 031026 (2023)] in terms of Born-Oppenheimer phonon frequencies and identify key simplifications that lead to current models. Our main findings are that the conventional equation of motion for coherent phonons needs revision, as it does not arise from the fpEE, and that the \(e\)-\(ph\) coupling should be replaced by an unconventional dynamically screened coupling. The fpEE is also used to develop a first-principles polaron theory of lattice distortions.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
9 pages
Silica Aerogel Thin Film on Improving Solar Cell Efficiency
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Silica aerogels are nanoporous materials with exceptional optical and physical properties, making them promising candidates to enhance solar cell efficiency as antireflective coatings. This study synthesized hydrophobic silica aerogel thin films under ambient conditions and characterized their porous structure, surface morphology, and optical performance. The films were deposited on monocrystalline silicon solar cells to assess their impact on photovoltaic properties. A two-step acid/base catalyzed sol-gel process was utilized, followed by solvent exchange and surface modification with trimethylchlorosilane. Structural analysis via SEM revealed successful deposition of crack-free films when aging occurred in an ethanol environment. The aerogel displayed considerable specific surface area (115 m2/g), porosity (77.92%), and surface roughness (55-78%) along with a low refractive index (1.05), benefiting light harvesting. Preliminary solar testing showed increased output voltage with a 0.2 mm aerogel coating versus a bare cell. Further IV measurements demonstrated enhanced charge transport and conversion efficiency for the treated cell. The antireflective and light-trapping effects of aerogel appear to improve photon absorption. This initial research validates the potential of ambient pressure-synthesized hydrophobic silica aerogels to increase the performance of silicon photovoltaics cost-effectively. Further optimization of film thickness and morphology could realize higher efficiency gains.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph)
Hedgehog-like spin texture in Sb-doped MnBi\(_2\)Te\(_4\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Meng Zeng, Shu Mo, Ke Zhang, Yu-Jie Hao, Yu-Peng Zhu, Xiang-Rui Liu, Cheng Zhang, Ming-Yuan Zhu, Shiv Kumar, Takuma Iwata, Koji Miyamoto, Taichi Okuda, Kenya Shimada, Kenta Kuroda, Xiao-Ming Ma, Chang Liu
We employ spin- and angle-resolved photoemission spectroscopy and circular-dichroism ARPES to systematically investigate the spin texture of Sb-doped MnBi\(_2\)Te\(_4\). Our results display a hedgehog-like spin texture in this system which is signified by reversed-orienting out-of-plane spins at the Dirac gap. Our finding reveals the presence of time-reversal symmetry breaking, implying the possibility for realization of high-temperature quantum anomalous Hall effect.
Materials Science (cond-mat.mtrl-sci)
12 pages, 4 figures
Odd-parity superconductivity underpinned by antiferromagnetism in heavy fermion metal YbRh\(_2\)Si\(_2\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
Lev V. Levitin, Jan Knapp, Petra Knappová, Marijn Lucas, Ján Nyéki, Petri Heikkinen, Vladimir Antonov, Andrew Casey, Andrew F. Ho, Piers Coleman, Christoph Geibel, Alexander Steppke, Kristin Kliemt, Cornelius Krellner, Manuel Brando, John Saunders
Topological superconductors are essential elements of the periodic table of topological quantum matter. However, the relevant odd-parity spin-triplet superconductors are rare. We report high-resolution measurements of the complex electrical impedance of YbRh\(_2\)Si\(_2\) down to 0.4 mK, that reveal the presence of several superconducting states, suppressed differently by magnetic field, both Pauli-limited and beyond the Pauli limit. Superconductivity is abruptly switched off at the critical field of the primary antiferromagnetic order. The onset of electro-nuclear spin density wave order enhances the superconductivity, which we account for by the simultaneous formation of a spin-triplet pair density wave. Together these observations provide compelling evidence for odd-parity superconductivity, and its underpinning by antiferromagnetism, and allow us to identify the topological helical state.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
24 pages, 4 main and 15 supplementary figures, 1 supplementary table
Ground state properties of a spin-\(\frac{5}{2}\) frustrated triangular lattice antiferromagnet NH\(_{4}\)Fe(PO\(_{3}\)F)\(_2\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
S. Mohanty, K. M. Ranjith, C. S. Saramgi, Y. Skourski, B. Büchner, H. -J. Grafe, R. Nath
Structural and magnetic properties of a two-dimensional spin-\(\frac{5}{2}\) frustrated triangular lattice antiferromagnet NH\(_{4}\)Fe(PO\(_{3}\)F)\(_2\) are explored via x-ray diffraction, magnetic susceptibility, high-field magnetization, heat capacity, and \(^{31}\)P nuclear magnetic resonance experiments on a polycrystalline sample. The compound portrays distorted triangular units of the Fe\(^{3+}\) ions with anisotropic bond lengths. The magnetic susceptibility shows a broad maxima around \(T^{\rm{max}}_{\chi}\simeq 12\) K, mimicking the short-range antiferromagnetic order of a low-dimensional spin system. The magnetic susceptibility and NMR shift could be modeled assuming the spin-\(5/2\) isotropic triangular lattice model and the average value of the exchange coupling is estimated to be \(J/k_{\rm B} \simeq 1.7\) K. This value of the exchange coupling is reproduced well from the saturation field of the pulse field data. It shows the onset of a magnetic ordering at \(T_{\rm N} \simeq 5.7\) K, setting the frustration ratio of \(f = \frac{|\theta_{\rm CW}|}{T_{\rm N}} \simeq 5.7\). Such a value of \(f\) reflects moderate magnetic frustration in the compound. The d\(M\)/d\(H\) vs \(H\) plots of the low temperature magnetic isotherms exhibit a sharp peak at \(H_{\rm SF} \simeq 1.45\) T, suggesting a field-induced spin-flop transition and magnetic anisotropy. The rectangular shape of the \(^{31}\)P NMR spectra below \(T_{\rm N}\) unfolds that the ordering is commensurate antiferromagnet type. Three distinct phase regimes are clearly discerned in the \(H - T\) phase diagram, redolent of a frustrated magnet with in-plane (XY-type) anisotropy.
Materials Science (cond-mat.mtrl-sci)
13 pages, 12 figures
Transport of ultracold dipolar fermions in one-dimensional optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Barnali Chakrabarti, N D Chavda, Andrea Trombettoni, Arnaldo Gammal
We investigate the transport properties in out-of-equilibrium dynamics of strongly correlated dipolar fermions initially localized in one-dimensional inhomogeneous optical lattice. The dynamics is studied by experimentally measurable dynamical variables such as one-body density, pair-correlation function and size of the expanding cloud. In the noninteracting limit, we trace the usual fingerprints of ballistic expansion in the short time dynamics. However, dynamics is strongly affected by system size due to Pauli principle. The dynamics also exhibits significant dependence on the sign of the interactions. We observe that strong repulsive dipolar interaction gives rise to many-body features in the dynamics, while strong attractive dipolar interaction leads to stabilized cluster states. Intermediate dipolar interaction are found to hinder expansion of correlations, while very strong dipolar interaction favors expansion of the cloud. Our work show the effect of dipolar interaction in the transport properties of interacting fermions, that can be studied in on-going experiments with ultracold dipolar fermions.
Quantum Gases (cond-mat.quant-gas)
New opportunities for high pressure hydrogen achieved by fullerane vibrating modes: an ab initio study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Leonard Constantin Gebac, Vasile Bercu
The encapsulation of hydrogen within fullerene/fullerane cages offers a promising avenue for studying high pressure hydrogen dynamics. Through ab initio molecular dynamics simulations, we investigate the behavior of a system consisting of hydrogen atoms enclosed in a dodecahedrane. Our findings reveal significant structural and dynamical changes as the cage undergoes compression, corresponding to radial symmetric vibration. We analyze geometric, energetic, and thermodynamic parameters, highlighting correlations and observing behavior analogous to high pressure phases of hydrogen. Notably, our study bridges the gap between theory and experiment by proposing a novel approach to achieving high pressures and temperatures experimentally. These results not only contribute to the understanding of hydrogen behavior under extreme conditions but also hold implications for the quest to attain metallic hydrogen - a milestone in materials science with potential applications in various fields.
Materials Science (cond-mat.mtrl-sci), Atomic and Molecular Clusters (physics.atm-clus)
19 pages, 4 figures
Brightening dark excitons and trions in systems with a Mexican-hat energy dispersion: example of InSe
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
Lewis J. Burke, Mark T. Greenaway, Joseph J. Betouras
We investigate the properties of momentum-dark excitons and trions formed in two-dimensional (2D) materials that exhibit an inverted Mexican-hat-shaped dispersion relation, taking monolayer InSe as an example. We employ variational techniques to obtain the momentum-dark and bright ground-states (non-zero and zero quasiparticle momenta, respectively). These states are of particular interest due to their peaks in the quasiparticle density of states, the largest contribution comes from the momentum-dark ground state due to the presence of a van Hove singularity (VHS). These momentum-dark systems require a physical process to provide the necessary momentum to become bright. We study the brightening of this state due to coupling with phonons and compute the resulting photoluminescence spectrum. This work opens new avenues of research, such as exploiting dark excitons in solar cells and other semiconductor-based optoelectronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
28 pages, 9 figures
Quicker flocking in aligning active matters for noisier beginning
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
Sohini Chatterjee, Sohom Das, Purnendu Pathak, Tanay Paul, Subir K. Das
The constituents in a class of active matter systems change their directions of motion by being influenced by the velocities of the neighbors. Such systems may undergo phase transitions, with respect to ordering in the velocity field, as well as clustering in the density field, when the strength of an externally imposed noise is varied. Via computer simulations, with a well-known model, that faithfully represents these systems, we show that evolutions in both clustering and ordering exhibit certain interesting features that were hitherto unrealized. The transformations occur quicker, following quenches to a fixed final state, below the transition point, for disordered starting states that are farther away from the ``critical" noise strength. This implies earliest arrival of the farthest, at a given destination. Detailed analysis of the results, combined with the outcomes from a similar study of para- to ferromagnetic transitions, show that the variation in critical fluctuations in the initial configurations can lead to such interesting effect. We quantify this via the Ornstein-Zernike theory.
Statistical Mechanics (cond-mat.stat-mech)
12 pages, 5 figures
WyckoffDiff - A Generative Diffusion Model for Crystal Symmetry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Filip Ekström Kelvinius, Oskar B. Andersson, Abhijith S. Parackal, Dong Qian, Rickard Armiento, Fredrik Lindsten
Crystalline materials often exhibit a high level of symmetry. However, most generative models do not account for symmetry, but rather model each atom without any constraints on its position or element. We propose a generative model, Wyckoff Diffusion (WyckoffDiff), which generates symmetry-based descriptions of crystals. This is enabled by considering a crystal structure representation that encodes all symmetry, and we design a novel neural network architecture which enables using this representation inside a discrete generative model framework. In addition to respecting symmetry by construction, the discrete nature of our model enables fast generation. We additionally present a new metric, Fréchet Wrenformer Distance, which captures the symmetry aspects of the materials generated, and we benchmark WyckoffDiff against recently proposed generative models for crystal generation.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI), Machine Learning (cs.LG)
Resonant spin amplification and accumulation in MAPbI\(_3\) single crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Erik Kirstein, Dmitri R. Yakovlev, Evgeny A. Zhukov, Nataliia E. Kopteva, Bekir Turedi, Maksym V. Kovalenko, Manfred Bayer
Quantum technologic and spintronic applications require reliable semiconducting materials that enable a significant, long-living spin polarization of electronic excitations and offer the ability to manipulate it optically in an external field. Due to the specifics of band structure and remarkable spin-dependent properties, the lead halide perovskite semiconductors are suitable candidates for that. Here, the carrier spin dynamics in a MAPbI\(_3\) (MA = methylammonium) perovskite single crystal with thickness of 20 \(\mu\)m are studied by the time-resolved Kerr ellipticity technique at cryogenic temperatures. Long times of longitudinal electron spin relaxation \(T_1 = 30\) ns and transverse electron spin dephasing \(T_{2,e}^\ast=21\) ns are found. The spin dynamics lasting longer than the applied laser pulse repetition period give rise to spin accumulation effects. We exploit them through the resonant spin amplification, polarization recovery, and spin inertia techniques to study the electron and hole spin systems coupled with the nuclear spins. These results establish the lead halide perovskite semiconductors as suitable platform for quantum technologies relying on spin-dependent phenomena.
Materials Science (cond-mat.mtrl-sci)
Crossover from BKT to first-order transition induced by higher-order terms in 2D XY models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
We study phase transitions in \(XY\) models, generalized by inclusion of \(n\) higher-order pairwise interactions of equal strength, by Monte Carlo simulation. It is found that by adding new terms the Berezinskii-Kosterlitz-Thouless (BKT) transition, observed in the standard \(XY\) model, gradually changes to the first-order phase transition. We determine the critical number of terms for which the first-order transition appears as \(n_c=6\). It is also found that for \(n=5\) the transition is pseudo-first-order but it becomes true first-order if the couplings are allowed to increase. In general, a more rapid increase of the coupling intensity supports the first-order transition, however, a too fast increase may result in splitting of the single transition to multiple transitions. Consequently, the minimal number of the terms required for the change of the BKT phase transition to first order in the present model with arbitrary couplings is estimated to be \(2 < n_c \leq 5\).
Statistical Mechanics (cond-mat.stat-mech)
12 pages, 6 figures
Electric Field-Induced Formation of a 2D Adatom Gas on Cryogenic Li Surfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Shyam Katnagallu, Huan Zhao, Se-Ho Kim, Baptiste Gault, Christoph Freysoldt, Jörg Neugebauer
Intense electrostatic fields, such as those able to break bonds and cause field-ion emission, can fundamentally alter the behaviour of atoms at and on the surface. Using density functional theory (DFT) calculations on the Li (110) surface under high electrostatic fields, we identify a critical field strength at which surface atoms occupying a kink site become thermodynamically unstable against adatom formation. This mechanism leads to the formation of a highly concentrated two-dimensional (2D) adatom gas on the surface. Moreover, the applied field reverses the stability of preferred adsorption sites, enabling barrierless diffusion of lithium atoms even well below the threshold required for field evaporation. The here identified mechanisms offer a unified explanation for experimental observations in atom probe tomography and for understanding high electric field phenomena in systems such as battery interfaces and electrochemical environments.
Materials Science (cond-mat.mtrl-sci)
A Grain Boundary Embrittlement Genome for Substitutional Cubic Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Nutth Tuchinda, Gregory B. Olson, Christopher A. Schuh
Grain boundary chemistry plays a critical role for the properties of metals and alloys, yet there is a lack of consistent datasets for alloy design and development. With the advent of artificial intelligence and machine learning in materials science, open materials models and datasets can be used to overcome such challenges. Here, we use a universal interatomic potential to compute a grain boundary segregation and embrittlement genome for the {}5001 grain boundary for FCC and BCC binary alloys. The grain boundary database calculated here serves as a design tool for the embrittlement of high-angle grain boundaries for alloys across 15 base metals system of Ag, Al, Au, Cr, Cu, Fe (both BCC and FCC), Mo, Nb, Ni, Pd, Pt, Rh, Ta, V and W with 75 solute elements for each.
Materials Science (cond-mat.mtrl-sci)
Finite temperature fermion Monte Carlo simulations of frustrated spin-Peierls systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
João C. Inácio, Jeroen van den Brink, Fakher F. Assaad, Toshihiro Sato
The Abrikosov fermion representation of the spin-1/2 degree of freedom allows for auxiliary-field quantum Monte Carlo simulations of frustrated spin systems. This approach provides a manifold of equivalent actions over which the negative sign problem can be optimised. As a result, we can reach temperature scales well below the magnetic scale. Here, we show how to generalise this algorithm to spin-Peierls systems. In contrast to exact diagonalisation approaches, Monte Carlo methods are not Hilbert space bound such that the computational effort per sweep remains invariant when adding phonons. However, the computational effort required to generate independent configurations increases in the presence of phonons. We also show that, for the specific case of the Kitaev-Heisenberg model, the inclusion of phonons does not render the negative sign problem more severe. This new algorithm hence allows us to investigate the interplay between phonon degrees of freedom and magnetic frustration. We present results for frustrated and non-frustrated spin systems.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 8 figures, article
Emulating Novel Topological Phases with Ultracold Fermions in Optical Lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Zhi Lin, Qi Song, Sheng Yue, Ming Yang, Jie Lou, Yan Chen
We propose a feasible scheme utilizing the Floquet engineering platform with ultracold atoms in optical lattices to emulate both pair-hopping processes and singlet/triplet pairing interactions, aiming to simulate and control novel topologically nontrivial phases. Our large-scale density matrix renormalization group (DMRG) simulations reveal three distinct topological regimes: (i) a Majorana-enabled spin-density-wave (MS) phase characterized by exponentially localized edge charges, non-local single-fermion edge correlations, a doubly degenerate entanglement spectrum; (ii) a \(z\)-axis polarized triplet superconducting (TS) phase manifesting fractionalized edge spin; and (iii) a novel x-directional triplet superconducting (XTS) phase exhibiting fractional edge spins along the \(x\)-direction and non-local single-particle edge correlations, merging characteristics of the edge states from both MS and TS phases. Therefore, our work establishes a versatile framework for exploring exotic quantum phases and non-Abelian edge states in number-conserving systems.
Quantum Gases (cond-mat.quant-gas), Superconductivity (cond-mat.supr-con)
5 pages,5 figures
Topological Constraint Model of Alkaline Earth Vanadate Glasses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Topological constraint theory has enabled the successful prediction of glass properties over a wide range of compositions. In this study, a topological constraint model is constructed for alkaline earth vanadate glasses based on experimental data. The change in vanadate structural units from VO5 to VO4 was modeled as a function of alkaline earth content and related to thermal and mechanical properties. The model covers both high and low-temperature properties to probe the temperature dependence of constraint rigidity for each constituent of the glass network. The model is changed to describe anomalies in magnesium sites potentially implying that magnesium can form locally rigid structures. Furthermore, the traditional understanding of vanadate glass structure is compared to recent results concluding that the terminal oxygen must exist as a part of the VO4 units. Results for the model explain that bridging oxygen constraints are the main contributors to network rigidity in both low and high temperature regimes. Vanadate glass networks are highly connected even with the introduction of modifier species, which introduce their own bond constraints. Corroboration between experimental data and the topological constraint model illustrates the role of alkaline earth oxides in the glass network.
Materials Science (cond-mat.mtrl-sci)
Magnons in chromium trihalides from Bethe-Salpeter equation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Ali Esquembre-Kučukalić, Khoa B. Le, Alberto García-Cristóbal, Marco Bernardi, Davide Sangalli, Alejandro Molina-Sánchez
Chromium trihalides (CrX\(_3\), with \(\rm{X=I,Br,Cl}\)) are layered ferromagnetic materials with rich physics and possible applications. Their structure consists of magnetic Cr atoms positioned between two layers of halide atoms. The choice of halide results in distinct magnetic properties, but their effect on spin-wave (magnon) excitations is not fully understood. Here we present first-principles calculations of magnon dispersions and wave functions for monolayer Cr trihalides using the finite-momentum Bethe-Salpeter equation (BSE) to describe collective spin-flip excitations. % We study the dependence of magnon dispersions on the halide species and resolve the small topological gap at the Dirac point in the magnon spectrum by including spin-orbit coupling. Analysis of magnon wave functions reveals that magnons are made up of electronic transitions with a wider energy range than excitons in CrX\(_3\) monolayers, providing insight into magnon states in real and reciprocal space. We discuss Heisenberg exchange parameters extracted from the BSE and discuss the convergence of BSE magnon calculations. Our work advances the quantitative modeling of magnons in two-dimensional materials, providing the starting point for studying magnon interactions in a first-principles BSE framework.
Materials Science (cond-mat.mtrl-sci)
Tunable exciton polaritons in biased bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
V. G. M. Duarte, P. Ninhos, C. Tserkezis, N. Asger Mortensen, N. M. R. Peres, A. J. Chaves
By harnessing the unique properties of bilayer graphene, we present a flexible platform for achieving electrically tunable exciton polaritons within a microcavity. Using a semiclassical approach, we solve Maxwell's equations within the cavity, approximating the optical conductivity of bilayer graphene through its excitonic response as described by the Elliott formula. Transitioning to a quantum mechanical framework, we diagonalize the Hamiltonian governing excitons and cavity photons, revealing the resulting polariton dispersions, Hopfield coefficients and Rabi splittings. Our analysis predicts that, under realistic exciton lifetimes, the exciton-photon interaction reaches the strong coupling regime. Furthermore, we explore the integration of an epsilon-near-zero material within the cavity, demonstrating that such a configuration can further enhance the light-matter interaction.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 5 figures, PRB Editor's suggestion
Phys. Rev. B 111, 075411 (2025)
Supersolid phases of bosons
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Supersolids--the enigmatic phase of quantum matter, with properties resembling both the superfluid and solid states--have been actively sought over the past 70 years. We provide a comprehensive review of the to-date development in experimental and theoretical studies of supersolid bosons, with a particular focus on their observation in ultracold atomic gases. Additionally, the use of optical lattice facilitates the realization of 'lattice-supersolids', which paves the way to study the effect of correlations in a controlled manner. A brief theoretical framework is presented to characterize this puzzling state with competing orders and to gain insight into its basic properties. Various types of supersolid phases and the different platforms used to achieve them are described. Finally, we discuss the future prospects of research and the potential to achieve supersolids with more exotic features.
Quantum Gases (cond-mat.quant-gas)
Survival probabilities in biased random walks: To restart or not to restart? that is the question
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-11 20:00 EST
The time-dependent survival probability function \(S(t;x_0,q)\) of biased Sisyphus random walkers, who at each time step have a finite probability \(q\) to step towards an absorbing trap at the origin and a complementary probability \(1-q\) to return to their initial position \(x_0\), is derived {}. In particular, we explicitly prove that the survival probability function of the walkers decays exponentially at asymptotically late times. Interestingly, our analysis reveals the fact that, for a given value \(q\) of the biased jumping probability, the survival probability function \(S(t;x_0,q)\) is characterized by a {} (marginal) value \(x^{\text{crit}}_0(q)\) of the initial gap between the walkers and the trap, above which the late-time survival probability of the biased Sisyphus random walkers is {} than the corresponding survival probability of standard random walkers.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
10 pages
Annals of Physics 415, 168109 (2020)
Filling a gap in materials mechanics: Nanoindentation at high constant strain rates upto \(10^5 s^{-1}\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-11 20:00 EST
Lalith Kumar Bhaskar, Dipali Sonawane, Hendrik Holz, Jeongin Paeng, Peter Schweizer, Jing Rao, Bárbara Bellón, Damian Frey, Aloshious Lambai, Laszlo Petho, Johann Michler, Jakob Schwiedrzik, Gaurav Mohanty, Gerhard Dehm, Rajaprakash Ramachandramoorthy
Understanding the dynamic behaviour of materials has long been a key focus in the field of high strain rate testing, and a critical yet unresolved question is whether flow stresses exhibit a significant strength upturn at strain rates ranging between \(10^3\) and \(10^4 s^{-1}\), and, if so, why. Current macro- and microscale mechanical testing is limited, as no single experimental method spans the entire strain rate range of \(10^2\) to \(10^5 s^{-1}\), where such an upturn is expected. In this study, we address these limitations using a highly customized piezoelectric in situ nanomechanical test setup, which enables, for the first time, constant indentation strain rates up to \(10^5 s^{-1}\). This system was employed to investigate the rate-dependent hardness in single-crystalline molybdenum, nanocrystalline nickel, and amorphous fused silica across strain rates of \(10^1\) to \(10^5 s^{-1}\), remarkably revealing an upturn in hardness in all three materials. The constancy of strain rate allowed, post-deformation microstructural analysis specific to the tested strain rates, shedding light on the potential mechanisms causing the hardness upturn.
Materials Science (cond-mat.mtrl-sci)
Topological Phase Transitions in Kagome Ferromagnets: The Role of Intrinsic Rashba Spin-Orbit Coupling
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-11 20:00 EST
Ritwik Das, Arkamitra Sen, Indra Dasgupta
The theoretically predicted Chern insulators have highlighted the potential of easy-axis kagome ferromagnets to host the quantum anomalous Hall effect. This phenomenon can also emerge from in-plane ferromagnetism in kagome systems via the breaking of both out-of-plane and in-plane mirror symmetries. In this paper, we demonstrate that the interplay between magnetism and mirror symmetries makes ferromagnetic kagome systems a versatile platform for realizing nontrivial topological phases, with the orientation of magnetic moments \(\hat{m}(\theta,\phi)\) at lattice sites serving as a key tuning parameter. We show that the Rashba spin-orbit coupling (SOC) induced by broken out-of-plane mirror symmetry together with the intrinsic SOC incorporated in a tight-binding model captures the rich topological phase diagram of kagome systems as a function of \(\hat{m}(\theta,\phi)\). In particular, the restoration of in-plane mirror symmetry for specific values of \(\phi\) promotes topological phase transition upon variation of in-plane orientation of the moments \(\hat{m}(\theta=90^{\circ},\phi)\). However the topological phase transition for the variation of \(\hat{m}(\theta,\phi=\)constant) is dictated by a competition between Rashba SOC and intrinsic SOC. Density functional theory calculations for the ferromagnetic kagome monolayer Co\(_3\)Pb\(_3\)S\(_2\), a representative compound belonging to the family Co\(_3\)X\(_3\)Y\(_2\) (X=Sn, Pb; Y=S, Se) further corroborate our predictions based on the proposed tight-binding model.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
6 pages, 4 figures
Theoretical Predictions of MB5N5: Atom-Stuffed Boronitride Clathrate Cages Derived from the High-Pressure Superhydride
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-11 20:00 EST
Nisha Geng, Giacomo Scillla, Eva Zurek
This study investigates 180 MX5Y5 (X, Y = B, C, or N) clathrate-like structures derived from MH10 superhydrides using high-throughput Density Functional Theory (DFT) geometry optimizations and phonon calculations. A wide variety of electropositive and electronegative encapsulated atoms were considered. From all of the studied systems only 31 MB5N5 phases were found to be dynamically stable at ambient pressure. The highest 1-atmosphere superconducting critical transition temperature was predicted for FB5N5. However, ab initio molecular dynamics simulations revealed that all of the identified superconducting phases decompose by 300~K at 1~atm, while only nine semiconducting phases remained thermally stable. Our findings underscore the critical role of kinetic and thermal stability in predicting viable superconductors. The electronic structure of the MB5N5 compounds were rationalized in terms of electron donating and withdrawing intercalants, and machine-learning based predictions of their mechanical properties were compared with those of an empty boronitride cage.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Dimer problem on a spherical surface
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
A. Tononi, D. S. Petrov, M. Lewenstein
We solve the problem of a dimer moving on a spherical surface and find that its binding energy and wave function are sensitive to the total angular momentum. The dimer gets squeezed in the direction orthogonal to the center-of-mass motion and can qualitatively change its geometry from two-dimensional to one-dimensional.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
7 pages, 3 figures
Persistent spin grids with spin-orbit coupled 2D electron gas
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-11 20:00 EST
We consider the diffusive spin dynamics of a 2D electron gas with spin-orbit coupling confined within a grid of narrow channels. We show that the lifetime of certain spin distributions in such grids greatly exceeds that in an unconfined 2D electron gas and diverges as the channel width approaches zero. Such persistent spin grids occur if the electron spin orientation remains invariant after diffusion around the grid plaquette. We establish a topological \(\mathbb{Z}_2\) classification for persistent spin grids and speculate that the setup can be used to simulate non-Abelian lattice gauge theories.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat)
6 pages, 3 figures
Observation of Magnon-Polarons in the Fermi-Hubbard Model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-11 20:00 EST
Max L. Prichard, Zengli Ba, Ivan Morera, Benjamin M. Spar, David A. Huse, Eugene Demler, Waseem S. Bakr
The interplay of magnetic excitations and itinerant charge carriers is a ubiquitous phenomenon in strongly correlated electron systems. In the vicinity of magnetically ordered phases, strong interactions between itinerant quasiparticles and magnetic excitations can result in the dramatic renormalization of both. A key theoretical question is understanding the renormalization of the magnon quasiparticle, a collective spin excitation, upon doping a magnetic insulator. Here, we report the observation of a new type of quasiparticle arising from the dressing of a magnon with the doped holes of a cold atom Fermi-Hubbard system, i.e. a magnon-Fermi-polaron. Utilizing Raman excitation with controlled momentum in a doped, spin-polarized band insulator, we address the spectroscopic properties of the magnon-polaron. In an undoped system with strong interactions, photoexcitation produces magnons, whose properties are accurately described by spin wave theory. We measure the evolution of the photoexcitation spectra as we move away from this limit to produce magnon-polarons due to dressing of the magnons by charge excitations. We observe a shift in the polaron energy with doping that is strongly dependent on the injected momentum, accompanied by a reduction of spectral weight in the probed energy window. We anticipate that the technique introduced here, which is the analog of inelastic neutron scattering, will provide atomic quantum simulators access to the dynamics of a wide variety of excitations in strongly correlated phases.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
15 pages, 10 figures