Mesoscale and Nanoscale Physics
Electrostatic Screening in Nanotubes: A Tubular Response Function Framework
Peter Gispert and Nikita Kavokine
The structure and transport of electrolytes in nanoscale channels are known to be affected by the electronic properties of the confining walls. This influence is particularly pronounced in quasi-one-dimensional nanotubes, where the high surface-to-volume ratio makes the wall the dominant source of electrostatic screening. For instance, ideal metallic tubes suppress long-range Coulomb interactions between ions exponentially. Yet, there exists no generic framework for evaluating electrostatic interactions in tubular confinement. Here, we introduce tubular response functions - a generalisation of surface response functions that captures how nanotubes with arbitrary electronic properties screen Coulomb interactions. Using this framework, we evaluate the interaction potential of ions confined in a metallic carbon nanotube, treating its long-range electronic properties exactly within a Luttinger
liquid model. We demonstrate that the screening characteristic of metallic armchair carbon nanotubes is almost identical to that of an ideal metal, regardless of electron density. We trace the origin of such strong screening to the
quantum confinement of electrons around the tube circumference and to the suppression of Friedel oscillations. Our framework opens the way for quantitative descriptions of ionic correlations and charge storage in nanotube-based electrodes, and can be further extended to address confined ion dynamics.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Boundary-Bulk Interplay in Nonlinear Topological Transport
Deyi Zhuo, Xiaoda Liu, Huu-Thong Le et al. (+7 more)
Nonlinear transport has emerged as a powerful approach to probe the
quantum geometry of electronic wavefunctions, such as Berry
curvature and
quantum metric, in topological materials. While nonlinear responses governed by bulk
quantum geometry and band
topology are well understood, the role of boundary modes (e.g., edge, surface, and hinge states) in nonlinear transport of topological materials remains largely unexplored. In this work, we demonstrate boundary-bulk interplay in nonlinear transport, including second-harmonic
Hall and nonreciprocal longitudinal responses, in molecular beam epitaxy-grown
magnetic topological
insulator heterostructures. We find that the nonlinear transport is maximized when the sample is tuned slightly away from the well-quantized states, including the
quantum anomalous
Hall and
axion insulator states. The sign and amplitude of the nonlinear transport depend on electrode configuration,
magnetic order, and carrier type, establishing boundary mode transport as the dominant contributor. These findings, supported by
symmetry analysis and nonlinear Landauer-Büttiker formalism, demonstrate that nonlinear transport in topological materials is governed by the interplay between boundary and bulk states. We further derive a universal relation between different lead voltages from electrode geometry
symmetry, which allows us to distinguish nonlinear boundary transport from bulk contributions. Our work highlights the critical role of electrodes in nonlinear transport, which is absent in nonlinear optics, and establishes boundary modes as a key origin of the
giant nonlinear response in nearly bulk-insulating topological materials. This insight opens new opportunities for engineering nonlinear transport through boundary-bulk interplay in future device applications of topological materials.
Read the full abstract ▾
All authors Deyi Zhuo, Xiaoda Liu, Huu-Thong Le, Annie G. Wang, Han Tay, Bomin Zhang, Ling-Jie Zhou, Binghai Yan, Chao-Xing Liu, Cui-Zu Chang
Statistical Mechanics
Statistical structural properties of many-body chaotic eigenfunctions and applications
Wen-ge Wang, Qingchen Li, Jiaozi Wang et al. (+1 more)
In this paper, we employ a semiperturbative theory to study the statistical structural properties of energy eigenfunctions (EFs) in many-body
quantum chaotic systems consisting of a central system coupled to an environment. Under certain assumptions, we derive both the average shape and the statistical fluctuations of EFs on the basis formed by the direct product of the energy eigenbases of the system and the environment. Furthermore, we apply our results to two fundamental questions: (i) the properties of the reduced density
matrix of the central system in an eigenstate, and (ii) the structure of the off-diagonal smooth function within the framework of the eigenstate thermalization hypothesis. Numerical results are also presented in support of our main findings.
Read the full abstract ▾
All authors Wen-ge Wang, Qingchen Li, Jiaozi Wang, Xiao Wang
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Analytic Theory and cQED Implementation of a Two-Qubit Refrigerator: Sub-100 mK Cavity Cooling from a 4 K Bath
Daryoosh Vashaee and Jahanfar Abouie
We develop a theoretical framework for cooling a microwave cavity mode using a Poisson stream of internally correlated pairs of two-level systems and analyze its performance under realistic dissipation. Starting from a Lindblad model of a
phonon-tethered cavity interacting with sequentially injected atom pairs, we derive closed-form expressions for the steady-state cavity occupation and effective temperature. Two coupling geometries are examined: a one-atom configuration, where only one member of each pair interacts with the cavity, and a two-atom configuration, where both atoms couple collectively. The single-atom model enables cooling below the
phonon bath but not below the reservoir temperature, whereas the two-atom scheme exhibits enhanced refrigeration - pair correlations modify the cavity's upward and downward transition rates so that the steady-state temperature can fall well below that of the reservoir for weak
phonon damping. We map the parameter space including detuning, coupling strength, damping, and intra-pair exchange, identifying cooling valleys near resonance and the crossover between reservoir- and
phonon-dominated regimes. The two-atom configuration thus realizes a genuine
quantum-enhanced cooling mechanism absent in the single-atom case. We further outline an experimental implementation using two superconducting
qubits repeatedly prepared, coupled, and reset inside a 3D cavity. Realistic reset and flux-tuning protocols support MHz-rate interaction cycles, enabling engineered reservoirs to impose cavity temperatures of 50-120 mK even when the cryostat is at ~1 K, offering a pathway to autonomous, on-chip refrigeration of microwave modes in scalable
quantum hardware.
Read the full abstract ▾
Superconductivity
Fabrication and characterization of Nb/Al-AlN /Nb superconducting tunnel junctions
Alexey Pavolotsky, François Joint, Udupa Sujit Manjunatha et al. (+6 more)
We report a Nb/Al-AlN /Nb superconducting tunnel junction process in which the AlN barrier is formed by
plasma nitridation using a compact microwave electron-cyclotron-resonance (ECR) nitrogen
plasma source integrated into a standard sputter cluster. This enables growth of uniform tunnel barriers across a broad range of specific resistances, with $R_n A$ down to $\approx 3,\Omega,\mu\mathrm{m}^2$. Junctions maintain excellent quality, exhibiting $R_j/R_n \ge 25$ at the highest barrier transparencies. We characterize resistivity, specific capacitance, and the
evolution of junction parameters under room-temperature aging and thermal annealing. A consistent calibration of the junction specific capacitance $C_s$ versus $R_n A$ is established and independently validated by the performance of demonstrator SIS mixers designed using the extracted $C_s$.
Read the full abstract ▾
All authors Alexey Pavolotsky, François Joint, Udupa Sujit Manjunatha, Victor Belitsky, Denis Meledin, Takafumi Kojima, Sho Masui, Ravishankar Narayanan, Vincent Desmaris
Materials Science · Cross-listed from cs.LG
OXtal: An All-Atom Diffusion Model for Organic Crystal Structure Prediction
Emily Jin, Andrei Cristian Nica, Mikhail Galkin et al. (+8 more)
Accurately predicting experimentally realizable 3D molecular
crystal structures from their 2D chemical graphs is a long-standing open challenge in computational chemistry called
crystal structure prediction (CSP). Efficiently solving this problem has implications ranging from pharmaceuticals to organic
semiconductors, as
crystal packing directly governs the physical and chemical properties of organic solids. In this paper, we introduce OXtal, a large-scale 100M parameter all-atom
diffusion model that directly learns the conditional joint distribution over intramolecular conformations and periodic packing. To efficiently scale OXtal, we abandon explicit equivariant architectures imposing inductive bias arising from
crystal symmetries in favor of data augmentation strategies. We further propose a novel crystallization-inspired
lattice-free training scheme, Stoichiometric
Stochastic Shell Sampling ($S^4$), that efficiently captures long-range interactions while sidestepping explicit
lattice parametrization – thus enabling more scalable architectural choices at all-atom resolution. By leveraging a large
dataset of 600K experimentally validated
crystal structures (including rigid and flexible molecules, co-
crystals, and solvates), OXtal achieves orders-of-magnitude improvements over prior ab initio machine learning CSP methods, while remaining orders of magnitude cheaper than traditional
quantum-chemical approaches. Specifically, OXtal recovers experimental structures with conformer $\text{RMSD}_1<0.5$ Å and attains over 80% packing similarity rate, demonstrating its ability to model both thermodynamic and kinetic regularities of molecular crystallization.
Read the full abstract ▾
All authors Emily Jin, Andrei Cristian Nica, Mikhail Galkin, Jarrid Rector-Brooks, Kin Long Kelvin Lee, Santiago Miret, Frances H. Arnold, Michael Bronstein, Avishek Joey Bose, Alexander Tong, Cheng-Hao Liu
Materials Science
Remote epitaxial frustration stabilizes a correlated interfacial state
Taehwan Jung, Nicholas Hagopian, Anshu Sirohi et al. (+7 more)
Remote epitaxy exploits substrate interactions transmitted across atomically thin materials to replicate substrate
crystal structure. Here we show that competition among
graphene-, substrate-, and reconstruction-derived interactions can instead produce frustration. Using GdAuGe films on $N$-layer
graphene/SiC(0001), we identify at intermediate $N$ a self-limited interfacial state with broken long-range translational order, accompanied by non-monotonic crystallographic orientation selection in the epitaxial film above. The frustrated interface is accompanied by strongly enhanced
magnetic irreversibility above 300 K, with an interface-dominated rather than volume-scaled response, linking epitaxial frustration to an emergent collective property. Annealing drives an initially epitaxial
crystal into the frustrated state, distinguishing it from kinetically trapped disorder. First-principles calculations reveal a multi-periodic interfacial potential that provides a microscopic basis for frustration. Together, these results establish epitaxial frustration as a materials-design principle for stabilizing correlated interfacial states and emergent collective properties.
Read the full abstract ▾
All authors Taehwan Jung, Nicholas Hagopian, Anshu Sirohi, Quinn Campbell, Chengye Dong, Zachary T. LaDuca, Tamalika Samanta, Joshua Robinson, Paul M. Voyles, Jason K. Kawasaki
Statistical Mechanics
Self-organized criticality in complex model ecosystems
Thibaut Arnoulx de Pirey
We show that spatial extensions of many-species population dynamics models, such as the Lotka-Volterra model with random interactions we focus on in this work, generically exhibit scale-free correlation functions of population sizes in the limit of an infinite number of species. Using dynamical mean-field theory, we describe the many-species system in terms of single-species dynamics with demographic and environmental noises. We show that the single-species model features a random mass term, or equivalently a random space-time averaged growth rate, poising some species very close to extinction. This introduces a hierarchy of ever larger correlation times and lengths as the extinction threshold is approached. In turn, every species, even those far from extinction, are coupled to these near-critical fields which combine to make fluctuations of population sizes generically scale-free. We argue that these correlations are described by exponents derived from those of directed percolation in spatial dimension $d=3$, but not in lower dimensions.
Read the full abstract ▾
Materials Science
Probing Anharmonic Lattice Dynamics and Thermal Transport in Layered Perovskite LiYTiO4 Anode
Lin Zhang, Wen Liu, Mingquan He et al. (+1 more)
Layered perovskite lithium yttrium titanate ($\rm LiYTiO_4$) has recently emerged as a promising low-potential, ultrahigh-rate intercalation-type anode material for lithium-ion batteries; however, its
lattice dynamics and thermal transport properties remain poorly understood, limiting a complete evaluation of its practical potential. Here, we combine experimental measurements with theoretical modeling to systematically investigate the anharmonic
lattice dynamics and heat transport in $\rm LiYTiO_4$. We employ a neural
evolution potential (NEP)-based framework that integrates the temperature-dependent effective potential method with the Wigner thermal transport (WTT) formalism, explicitly including both diagonal and off-diagonal terms of the heat-flux operator. Zero-temperature
phonon calculations reveal dynamical instabilities associated with $\rm TiO_6$ octahedral rotation, which are stabilized at finite temperatures through anharmonic renormalization. Using the WTT approach with contributions from
phonon propagation and coherence contributions, we predict a room-temperature
lattice thermal conductivity ($\kappa_{\rm L}$) of 3.8 $\rm Wm^{-1}K^{-1}$ averaged over all
crystal orientations, in close agreement with the measured value of 3.2 \pm 0.08 $\rm Wm^{-1}K^{-1}$ for polycrystalline samples. To further examine the possible influence of ionic motion on high-temperature thermal transport, we compute $\kappa_{\rm L}$ using a Green-Kubo
equilibrium molecular dynamics approach based on the same NEP, which yields consistent results with both experiment and WTT predictions, confirming the negligible role of Li-ion mobility in heat conduction. Our study not only identifies the ultralow thermal conductivity of $\rm LiYTiO_4$ as a key limitation for its practical application but also establishes a reliable computational framework for studying thermal properties in battery materials.
Read the full abstract ▾
All authors Lin Zhang, Wen Liu, Mingquan He, Jun Huang
Superconductivity
Optical conductivity of a dirty current-carrying superconductor
Artem V. Polkin and Mikhail A. Skvortsov
We develop a full microscopic theory for the optical conductivity, $\sigma(\omega)$, of a dirty current-carrying
superconductor. Within the Keldysh sigma model formalism, we obtain the general analytical expression for $\sigma(\omega)$, applicable for arbitrary frequency $\omega$, temperature $T$, and dc supercurrent $I$. In addition to altering the usual Mattis-Bardeen conductivity, $\sigma_1(\omega)$, a finite supercurrent introduces two new contributions: $\sigma_2^\text{qp}(\omega)$ from quasiparticle redistribution and $\sigma_2^\text{SH}(\omega)$ from the amplitude (Schmid-
Higgs) mode excitation by the ac field. We investigate, both analytically and numerically, the main features of the optical conductivity in the presence of a dc supercurrent. They include a peak in $\text{Re}\,\sigma(\omega)$ above the optical gap and a sign change of $\text{Im}\,\sigma(\omega)$, with both effects becoming more pronounced at higher $I$ and lower $T$. We also elucidate the role of inelastic relaxation, which governs the low-frequency response, leading to a
giant microwave absorption and a suppression of the apparent superfluid density at the critical current. The optical conductivity measurement of a
superconductor biased by a finite dc supercurrent enables the direct observation of the Schmid-
Higgs mode via transport measurements.
Read the full abstract ▾
Materials Science
Confinement-Driven Exciton Behavior in 2D Halide Perovskites from Dielectric-Dependent Hybrid Methods
Rafael B. Araujo, Mustafa Mahmoud Aboulsaad, Sebastian E. Reyes-Lillo et al. (+1 more)
Understanding how dielectric anisotropy governs excitonic behavior in two-dimensional (2D) halide perovskites is critical for predicting and engineering their optoelectronic properties. In this work, we investigate Cs(n+1)PbnBr3n+1 nanoplatelets (n = 2-5) experimentally and theoretically and show that the interplay between dielectric confinement and anisotropic screening critically determines both their electronic structure and excitonic landscape. To incorporate the dielectric screening effects, the Coulomb kernel in the Fock exchange term is refined using a model dielectric function together with a model Bethe-Salpeter Equation approach. The
exciton binding energies show a monotonic decrease from 0.26 eV to 0.21 eV from n = 2 to 5, with 20 meV decrease per layer up to n = 4, and thereafter less change. The relatively small change per layer is a consequence of the strong spatial localization of
excitons. By analyzing directionally resolved dielectric tensors, we demonstrate that the in-plane dielectric constant predominantly dictates optical transitions and is close to converging to the bulk value already at n = 5, while the out-of-plane dielectric response reflects the confined nature of excitonic wave functions as expected. Our calculated absorption spectra capture experimental results within 0.02 eV throughout the confinement regime (n = 2-5). The effects of
lattice dynamics on the dimensionally dependent dielectric response and subsequent
exciton screening occurring on longer time-scales than the optical response are also analyzed, important for analysis and interpretation of
exciton lifetime,
diffusion, and band
alignments. The results establish a clear correlation between dielectric anisotropy, electronic structure, and
exciton binding energy at different timescales in layered perovskites, providing essential insight for the design of 2D optoelectronic materials and devices.
Read the full abstract ▾
All authors Rafael B. Araujo, Mustafa Mahmoud Aboulsaad, Sebastian E. Reyes-Lillo, Tomas Edvinsson
Soft Condensed Matter
Surface-directed spinodal decomposition in binary fluid mixtures on an amorphous wall: A molecular dynamics study
Syed Shuja Hasan Zaidi, Madhu Priya, Sanjay Puri et al. (+1 more)
We present molecular dynamics (MD) results to discuss wetting kinetics in binary fluid mixtures ($A:B=50:50$) undergoing surface-directed spinodal decomposition (SDSD) on an amorphous wall. Our simulations show the formation of a wetting layer rich in the preferred $A$-type particles and bicontinuous domain morphology in the bulk. In addition, the mixture maintains connectivity between the bulk and the wetting layer through $A$-rich tubes throughout the depletion region. The wetting layer thickness coarsens as a power law, $R_1(t)\sim t^{\alpha}$, with two distinct growth regimes of $\alpha=1/3$ and $\alpha=1$ active for at least a decade. The computed crossover time for $\alpha=1/3 \to 1$ equaled the reported bulk crossover time, and the corresponding crossover length scale $R_c$ agrees well with the expression $\Lambda = \sqrt{2k/\gamma_0}$ given by Scholten et al.~[Macromolecules2005, 38, 3515] for bicontinuous domains in aqueous
polymer mixtures in the presence of only one dominant length scale. This agreement supports a hydrodynamic picture of diffusive growth for the interconnected wetting layer and bulk domains, where the bending contribution ($k$) of
curvature-dependent $AB$ interfacial tension ($\gamma$) governs small-scale coarsening, producing $t^{1/3}$ growth. For length scales beyond $\Lambda$, capillary flows yield the viscous hydrodynamic regime ($\sim t$). Our results show no orientational effects on the domain coarsening parallel and perpendicular to the wall, contrasting many continuum models, including combinations with Flory-Huggins theory.
Read the full abstract ▾
All authors Syed Shuja Hasan Zaidi, Madhu Priya, Sanjay Puri, Prabhat K. Jaiswal
Materials Science
Spontaneous Transition from Conformal to Two-Dimensional Growth in Ge/GeSn Core/Shell Nanowires
Simone Assali, Sebastian Koelling, Milenka Andelic et al. (+3 more)
GeSn
semiconductors are group-IV isovalent
alloys that offer remarkable tunability of optoelectronic properties across the entire infrared spectrum, while remaining fully compatible with silicon processing standards. These attributes make GeSn a promising platform for scalable sensing, imaging, and communication technologies. Yet, the influence of dimensionality on GeSn
crystal growth remains poorly understood, limiting the development of integrated nanoscale infrared devices. Here, we reveal the spontaneous formation of hitherto unreported ultra-thin GeSn fins with sub-30 nm thickness during vapor-phase growth on Ge nanowire substrates. A transition from the typical conformal GeSn shell to distinct fin-like structures occurs along the nanowire growth axis and is accompanied by ordered twin defects extending longitudinally and laterally, inducing a transition from diamond to hexagonal-like
crystal structure. The fins exhibit uniform Sn incorporation of approximately 16 at.% throughout their volume, indicating high compositional homogeneity. These findings uncover an anisotropic growth regime in metastable GeSn
alloys, enriching the fundamental understanding of nanoscale epitaxy.
Read the full abstract ▾
All authors Simone Assali, Sebastian Koelling, Milenka Andelic, Lu Luo, Gianluigi Botton, Oussama Moutanabbir
Superconductivity · Cross-listed from quant-ph
Single Flux Quantum Circuit Operation at Millikelvin Temperatures
Jason Walter, Adam C. Weis, Kan-Ting Tsai et al. (+6 more)
As
quantum computing processors increase in size, there is growing interest in developing cryogenic electronics to overcome significant challenges to system scaling. Single flux-
quantum (SFQ)
circuits offer a promising alternative to remote, bulky, and power-hungry room temperature electronics. To meet the need for digital
qubit control, readout, and co-processing, SFQ
circuits must be adapted to operate at millikelvin temperatures near
quantum processors. SEEQC's SFQuClass digital
quantum management approach proximally places energy-efficient SFQ (ERSFQ)
circuits and
qubits in a multi-chip module. This enables extremely low power dissipation, compatible with a typical dilution cryostat's limited cooling power, while maintaining high processing speed and low error rates. We report on systematic testing from 4 K to 10 mK of a comprehensive set of ERSFQ
cells, as well as more complex
circuits such as programmable counters and demultiplexers used in digital
qubit control. We compare the operating margins and error rates of these
circuits and find that, at millikelvin, bias margins decrease and the center of the margins (i.e., the optimal bias current value) increases by ~15%, compared to 4.2 K. The margins can be restored by thermal annealing by reducing Josephson junction (JJ) critical current Ic. To provide guidance for how
circuit parameters vary from 4.2 K to millikelvin, relevant analog process control monitors (PCMs) were tested in the temperature range of interest. The measured JJ critical current (of the PCM JJ arrays) increases by ~15% when decreasing temperature from 4.2 K to millikelvin, in good agreement with both theory and the empirically measured change in the center of bias margins for the tested digital
circuits.
Read the full abstract ▾
All authors Jason Walter, Adam C. Weis, Kan-Ting Tsai, Meng-Ju Yu, Naveen Katam, Alex F. Kirichenko, Oleg A. Mukhanov, Shu-Jen Han, Igor V. Vernik
Statistical Mechanics
Geometry protected probabilistic structure in many-body dynamics
Yue Liu, Chushun Tian and Dahai He
Insomuch as statistical mechanics circumvents the formidable task of addressing many-body dynamics, it remains a challenge to derive macroscopic properties from a solution to
Hamiltonian equations for microscopic motion of an isolated system. Launching new attacks on this long-standing problem – part of
Hilbert's sixth problem – is urgently important, for focus of statistical phenomena is shifting from a fictitious ensemble to an individual member, i.e. a mechanically isolated system. Here we uncover a common probabilistic structure, the concentration of measure, in
Hamiltonian dynamics of two families of systems, the
Fermi-Pasta-Ulam-Tsingou (FPUT) model which is finite-dimensional and (almost) ergodic, and the Gross-Pitaevskii equation (GPE) which is infinite-dimensional and suffers strong ergodicity breaking. That structure is protected by the geometry of phase space and immune to ergodicity breaking, leading to counterintuitive phenomena. Notably, an isolated FPUT behaves as a thermal ideal gas even for strong modal interaction, with the thermalization time analogous to the Ehrenfest time in
quantum chaos, while an isolated GPE system, without any
quantum inputs, escapes the celebrated ultraviolet catastrophe through nonlinear wave localization in the mode space, and the Rayleigh-Jeans
equilibrium sets in the localization volume. Our findings may have applications in nonlinear optics and cold-atom dynamics.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Interactions of electrons and Rydberg excitons in two-dimensional semiconductors
Arthur Christianen, Anna M. Seiler, Alperen Tüğen et al. (+1 more)
Rydberg
excitons in two-dimensional
semiconductors provide sensitive and non-destructive probes of physics in proximal sample layers that host correlated electronic states. In particular, electron or hole doping of the sample layer is heralded by a strong frequency shift and loss of transition strength of 2s
excitons in the sensor layer. In analogy to the attractive polaron observed near the 1s
exciton, this redshifted resonance, which we term Rydberg attractive polaron (RAP), has been attributed to the formation of a bound state of a 2s
exciton and a remote electron. Through a theoretical analysis of
exciton-electron scattering, we show that the nature of the RAP and its underlying trion can only be explained by electron-mediated hybridization of 2s, 2p and interlayer
excitons, endowing the RAP a different structure than the 1s attractive polaron. We anticipate that this new understanding will ensure a more accurate assessment of the signatures of correlated electrons in two dimensional materials.
Read the full abstract ▾
All authors Arthur Christianen, Anna M. Seiler, Alperen Tüğen, Ataç İmamoğlu
Materials Science
Observation of Stable Bimeron Transport Driven by Spoof Surface Acoustic Waves on Chiral Metastructures
Huaijin Ma, Te Liu, Jiachen Sheng et al. (+3 more)
Topological quasiparticles, such as merons and bimerons, are characterized by non-trivial textures that exhibit remarkably robust transport against deformation, offering significant potential for information processing. While these phenomena have been explored in various systems, acoustic realizations remain challenging. Here, we report that acoustic meron topological textures were successfully realized using designed Archimedeanlike square spiral metastructures via the excitation of spoof surface acoustic waves (SSAWs). By applying mirror-symmetric combinatorial operations to the unit structures, we further construct composite
chiral metastructures that enable both one-dimensional and two-dimensional stable transport of acoustic bimerons. It is further revealed that bimeron transport originates from the locked opposite phase differences of SSAWs, induced by the handedness of the cavity resonant modes. The intrinsic robustness of the meron textures against structural defects is confirmed through the calculation of their topological charge. Our findings establish stable acoustic bimeron transport as a topologically resilient foundation for future acoustic information processing and storage technologies.
Read the full abstract ▾
All authors Huaijin Ma, Te Liu, Jiachen Sheng, Kaiyan Cao, Jinpeng Yang, Jian Wang
Disordered Systems and Neural Networks · Cross-listed from physics.optics
Multiple reentrant topological windows induced by generalized Bernoulli disorder
Ruijiang Ji, Yunbo Zhang, Shu Chen et al. (+1 more)
We investigate reentrant topological transitions in a one-dimensional Su-Schrieffer-Heeger chain with generalized Bernoulli disorder in the intradimer hopping amplitudes. Owing to its independently tunable values and probabilities, the multivalued disorder distribution provides a direct way to control the topological phase diagram. We show that increasing the disorder strength can split the nontrivial regime into multiple disconnected topological windows, whose number, widths, and locations are determined by the distribution parameters. The phase boundaries are derived analytically from the zero-mode inverse localization length and are governed by a weighted
geometric mean of the disordered hopping amplitudes, in agreement with numerical results from the reflection-
matrix topological
quantum number and the real-space winding number. We also show that the mean
chiral displacement dynamically identifies these reentrant windows. These results demonstrate how multivalued random disorder can organize and tune reentrant topological behavior in one-dimensional
chiral lattices.
Read the full abstract ▾
All authors Ruijiang Ji, Yunbo Zhang, Shu Chen, Zhihao Xu
Materials Science
Exchange interaction in ACu3Fe2Re2O12 quadruple perovskites
Fedor Temnikov, Alexey V. Ushakov, Evgenia V. Komleva et al. (+4 more)
Quadruple perovskites ACu$_3$Fe$_2$Re$_2$O$_{12}$ attract considerable interest due to their high Curie temperatures (up to $710$K), which strongly depend on the A-site cation. In this work, we employ first-principles calculations to investigate their electronic structure and
magnetic exchange interactions. A band mechanism of magnetism that explains the
antiferromagnetic character of the exchange interactions and their strong dependence on the filling of the Re $t_{2g}$ states is proposed. These
antiferromagnetic interactions stabilize ferrimagnetic ground state. The calculated Curie temperatures, obtained within the Onsager reaction field theory, are in a good agreement with experimental data.
Read the full abstract ▾
All authors Fedor Temnikov, Alexey V. Ushakov, Evgenia V. Komleva, Zhehong Liu, Youwen Long, Valentin Yu. Irkhin, Sergey V. Streltsov
Statistical Mechanics
Free energy dissipation and a decomposition of general jump diffusions on $\mathbb{R}^n$ without detailed balance
Shuyuan Fan and Qi Zhang
We analyze the thermodynamic structure of jump
diffusions combining Brownian and Poisson noise, a class of
stochastic dynamics relevant to non-
equilibrium statistical physics. For such nonlocal dynamics, the free energy admits a full dissipation formula that decomposes into
entropy production and housekeeping heat. A central result is a decomposition of the generator into symmetric and anti-symmetric parts with respect to the invariant measure $\rho_\mathrm{ss}$. The symmetric sector corresponds to a reversible dynamics and yields a nonlocal Fisher information governing free-energy decay, whereas the anti-symmetric sector generates a canonical conservative flow that produces circulation but no dissipation. Several numerical examples motivated by intracellular particle transports demonstrate how this decomposition clarifies the structure of non-
equilibrium stationary states in jump-driven systems.
Read the full abstract ▾
Materials Science
Morphology-engineered nanostructured silver- and antimony-telluride films for flexible thermoelectric generators
Ankit Kashyap, Conner Wallace, Geetu Sharma et al. (+7 more)
Harvesting low-grade heat to electricity is attractive for powering wearable electronic devices. Here, we demonstrate nW-scale thermoelectric power generation in devices from thin film assemblies of microwave-synthesized p-Sb2Te3 nanoplates and n-Ag2Te nanowires on polyvinylidene fluoride membranes. While microwave cycling is crucial for Ag2Te nanocrystal shaping, Sb2Te3 formation is sensitive to precursors and surfactant concentrations. Introducing S doping in Sb2Te3 in the 1 - 1.5 atomic percent range via thioglycolic acid during synthesis yields an up to eightfold higher power-factor, due to a fivefold increase in electrical conductivity and 25% increase in Seebeck coefficient. Our microfilm devices generate up to 33.6 mV from 5 deg C to 50 deg C thermal gradients, with 120 nW maximum power output at Delta T 30 deg C, which is sixtyfold higher than Sb2Te3 paper devices. Mechanical bending can increase device resistance by up to 125% due to diminished inter-nanostructure electronic transport. These findings provide insights for integrating synthesis, morphology engineering and device design for next-generation wearable thermoelectric systems.
Read the full abstract ▾
All authors Ankit Kashyap, Conner Wallace, Geetu Sharma, Collin Rowe, Mahima Sasikumar, Niraj Kumar Singh, Per Eklund, Theodorian Borca-Tasciucc, Ganpati Ramanath, Ajay Soni
Materials Science
Breaking the Boundaries of the Goldschmidt Tolerance Factor with Ethylammonium Lead Iodide Perovskite Nanocrystals
C. Meric Guvenc, Stefano Toso, Yurii P. Ivanov et al. (+4 more)
We report the synthesis of ethylammonium lead iodide (EAPbI3) colloidal nanocrystals as another member of the lead halide perovskites family. The insertion of an unusually large A-cation (274 pm in diameter) in the perovskite structure, hitherto considered unlikely due to the unfavorable Goldschmidt tolerance factor, results in a significantly larger
lattice parameter compared to the Cs-, methylammonium- and formamidinium-based lead halide perovskite homologues. As a consequence, EAPbI3 nanocrystals are highly unstable, evolving to a non-perovskite delta-EAPbI3 polymorph within one day. Also, EAPbI3 nanocrystals are very sensitive to electron irradiation and quickly degrade to PbI2 upon exposure to the electron beam, following a mechanism similar to that of other hybrid lead iodide perovskites (although degradation can be reduced by partially replacing the EA+ ions with Cs+ ions). Interestingly, in some cases during this degradation the formation of an epitaxial interface between (EAxCs1-x)PbI3 and PbI2 is observed. The photoluminescence emission of the EAPbI3 perovskite nanocrystals, albeit being characterized by a low
quantum yield (around 1%), can be tuned in the 664-690 nm range by regulating their size during the synthesis. The emission efficiency can be improved upon partial alloying at the A site with Cs+ or formamidinium cations. Furthermore, the morphology of the EAPbI3 nanocrystals can be chosen to be either nanocube or nanoplatelet, depending on the synthesis conditions.
Read the full abstract ▾
All authors C. Meric Guvenc, Stefano Toso, Yurii P. Ivanov, Gabriele Saleh, Sinan Balci, Giorgio Divitini, Liberato Manna
Materials Science
Near-Infrared Light Emitting Metal Halides: Materials, Mechanisms, and Applications
Ying Liu, Francesco Di Stasio, Chenghao Bi et al. (+4 more)
Near-Infrared (NIR) light emitting metal halides are emerging as a new generation of optical materials owing to their appealing features, which include low-cost synthesis, solution processability and adjustable optical properties. NIR emitting perovskite-based light-emitting diodes (LEDs) have reached an external
quantum efficiency (EQE) over 20% and a device stability of over 10,000 h. Such results have sparked an interest in exploring new NIR metal halide emitters. In this review, we summarize several different types of NIR-emitting metal halides, including lead/tin bromide/iodide perovskites, lanthanide ions doped/based metal halides, double perovskites, low dimensional hybrid and Bi3+/Sb3+/Cr3+ doped metal halides, and assess their recent advancements. The characteristics and mechanisms of narrow-band or broadband NIR luminescence in all these materials are discussed in detail. We also highlight the various applications of NIR-emitting metal halides and provide an outlook for the field.
Read the full abstract ▾
All authors Ying Liu, Francesco Di Stasio, Chenghao Bi, Jibin Zhang, Zhiguo Xia, Zhifeng Shi, Liberato Manna
Materials Science
Polaron-Driven Spin Funneling through Rashba-Split Bands in Mixed-Phase Quasi-Two-Dimensional Ruddlesden-Popper Perovskites
Sushovan Sarkar, Koushik Gayen, Ashish Soni et al. (+1 more)
Metal halide perovskites (MHPs) exhibit pronounced
spin-orbit coupling (SOC) as a result of their heavy metal constituents, leading to distinctive electronic properties such as Rashba type band splitting which make them promising candidates for next generation spintronic applications. Here, using circularly polarized luminescence (CPL) and polarization dependent pump-probe spectroscopy, we found that
spin polarization is present across all phases of our two-dimensional (2D) Ruddlesden-Popper (RP) mixed-phase perovskites, (C6H7SNH3)2 (CH3NH3)n-1PbnI3n+1 (n=1-4), irrespective of the number of inorganic layers. The origin of these
spin polarized bands is attributed to the Rashba effect. Interestingly, the highly disordered nature of this system facilitates remarkably efficient ultrafast funneling of photoexcited
spin-polarized
excitons from the pure 2D phase (n=1) to higher-n phases at room temperature. We demonstrate that significant polaron formation due to the inherent soft
crystal lattice and higher
exciton-
phonon interaction is responsible for the observed
spin funneling effect in mixed-phase 2D RP perovskites. Polaron act as a protective mechanism for
spin-polarized
excitons, preserving their
spin information through the screening of omnipresent
phonon-induced momentum scattering. These findings not only offer valuable guidance for the design of 2D RP perovskites with pronounced Rashba effects but also unveil a compelling class of solution-processed perovskites capable of efficient
spin-preserving energy transport at room temperature.
Read the full abstract ▾
All authors Sushovan Sarkar, Koushik Gayen, Ashish Soni, Suman Kalyan Pal
Materials Science
Light-Emitting Diodes based on Metal Halide Perovskite and Perovskite Related Nanocrystals
Ying Liu, Zhuangzhuang Ma, Jibin Zhang et al. (+5 more)
Light-emitting diodes (LEDs) based on halide perovskite nanocrystals have attracted extensive
attention due to their considerable luminescence efficiency, wide color gamut, high color purity, and facile material synthesis. Since the first demonstration of LEDs based on MAPbBr3 nanocrystals were reported in 2014, the community has witnessed a rapid development in their performances. In this review, we provide a historical perspective of the development of LEDs based on halide perovskite nanocrystals and then present a comprehensive survey of current strategies to high-efficiency lead-based perovskite nanocrystals LEDs, including synthesis optimization, ion doping/alloying and shell coating. We then review the basic characteristics and emission mechanisms of lead-free perovskite and perovskite-related nanocrystals emitters in environmentally friendly LEDs, from the standpoint of different emission colors. Finally, we cover the progress in LED applications and provide an outlook of the opportunities and challenges for future developments in this field.
Read the full abstract ▾
All authors Ying Liu, Zhuangzhuang Ma, Jibin Zhang, Yanni He, Jinfei Dai, Xinjian Li, Zhifeng Shi, Liberato Manna
Strongly Correlated Electrons
Real-Time Dynamics in Two Dimensions with Tensor Network States via Time-Dependent Variational Monte Carlo
Yantao Wu and Jannes Nys
Reliably simulating two-dimensional many-body
quantum dynamics with projected entangled pair states (PEPS) has long been a difficult challenge. In this work, we overcome this barrier for low-energy
quantum dynamics by developing a stable and efficient time-dependent variational Monte Carlo (tVMC) framework for PEPS. By analytically removing all gauge redundancies of the PEPS
manifold and exploiting tensor locality, we obtain a numerically well-conditioned tVMC equation. This enables long-time
evolution in previously inaccessible regimes. We explain how the difficulties in the traditional approach, particularly those associated with gauge redundancies, are resolved within tVMC. We demonstrate the power and generality of the method through five representative real-time local quench dynamics in two dimensions: (I)
chiral edge propagation in a free-
fermion Chern
insulator; (II) vison propagation in a pure Z2 gauge theory; (III) vison confinement dynamics in a Z2
lattice gauge theory coupled to
Higgs field; (IV) fractionalized charge transport in a fractional Chern
insulator; and (V) superfluidity and critical velocity in interacting
bosons. All simulations are performed on >= 10 x 10
lattices with
evolution times beyond T = 10 using modest computational resources. In addition, we also simulate the paradigmatic dynamics of the Ising model following a global quench at the critical transverse field, and obtain, with modest bond dimension, agreement with previous results. The method significantly extends the reach of classical tensor-network simulations for studying elementary excitations in
quantum many-body systems in real-time and provides a valuable computational counterpart to emerging
quantum simulators. As a by-product in the development, we also present a new form of minSR, which is more stable and offers a new perspective on tVMC.
Read the full abstract ▾
Materials Science
Halide Perovskite-Chalcohalide Nanocrystal Heterostructures as a Platform for the Synthesis and Investigation of the CsPbCl3-CsPbI3 Epitaxial Interface
Nikolaos Livakas, Irina Skvortsova, Juliette Zito et al. (+10 more)
Halide exchange in lead-based halide perovskites has been studied extensively. While mixed Cl-Br or Br-I
alloy compositions can be formed with no miscibility gaps, this is precluded for mixed Cl-I compositions, due to the large difference in Cl and I ionic radii. Here, we exploit perovskite-chalcohalide CsPbCl3-Pb4S3Cl2
heterostructures to study the Cl-I exchange and isolate new types of intermediate structures. The epitaxial interface between the Pb4S3Cl2 chalcohalide and the CsPbCl3 perovskite domain significantly influences the intermediate stages of halide exchange in the perovskite domain, leading to coexisting CsPbCl3 and CsPbI3 domains, thereby delivering segmented CsPbI3-CsPbCl3-Pb4S3Cl2 energetically favorable
heterostructures, with partial iodide alloying of the CsPbCl3 domain and at the perovskite-chalcohalide interface. The I:CsPbCl3 domain between CsPbI3 and Pb4S3Cl2 enables a gradual
lattice expansion across the
heterostructure. This design accommodates interfacial strain, with a 5.6% mismatch at the CsPbCl3-CsPbI3 interface and a 3.4% mismatch at the perovskite-chalcohalide interface. Full halide exchange leads to CsPbI3-Pb4S3Cl2
heterostructures. Both in intermediate and fully exchanged
heterostructures, the CsPbI3 domain is emissive. In the intermediate structures, the band
alignment between the two perovskite domains is type-I, with carriers photogenerated in the CsPbCl3 domain quickly transferring to the CsPbI3 domain, where they can recombine radiatively.
Read the full abstract ▾
All authors Nikolaos Livakas, Irina Skvortsova, Juliette Zito, Yurii P. Ivanov, Aswin Asaithambi, Andrea Toma, Annick De Backer, Muhammad Imran, Sandra Van Aert, Giorgio Divitini, Ivan Infante, Sara Bals, Liberato Manna
Materials Science
Nanocrystals Heterostructures based on Halide Perovskites and Metal Sulfides
Nikolaos Livakas, Juliette Zito, Yurii P. Ivanov et al. (+4 more)
We report the synthesis of nanocrystal
heterostructures composed of CsPbCl3 and PbS domains sharing an epitaxial interface. We were able to promote the growth of a PbS domain (in competition with the more commonly observed Pb4S3Cl2 one) on top of the CsPbCl3 domain by employing Mn2$^+$ ions, the latter acting most likely as scavengers of Cl$^-$ ions. Complete suppression of the Pb4S3Cl2 domain growth was then achieved by additionally selecting an appropriate sulfur source (bis(trimethylsilyl)sulfide, which also acted as scavenger of Cl$^-$ ions), and reaction temperature. In the
heterostructures, emission from the perovskite domain was quenched, while emission from the PbS domain was observed, pointing to a type-I band
alignment, as confirmed by calculations. These
heterostructures in turn could be exploited to prepare second-generation
heterostructures through selective ion exchange on the individual domains (halide ion exchange on CsPbCl3, cation exchange on PbS). We demonstrate the cases of Cl$^-$ to Br$^-$ and Pb2$^+$ to Cu$^+$ exchanges, which deliver CsPbBr3@PbS and CsPbCl3@Cu2-xS epitaxial
heterostructures, respectively.
Read the full abstract ▾
All authors Nikolaos Livakas, Juliette Zito, Yurii P. Ivanov, Clara Otero Martínez, Giorgio Divitini, Ivan Infante, Liberato Manna
Disordered Systems and Neural Networks · Cross-listed from hep-lat
A Machine Learning study of the two-dimensional antiferromagnetic $Q$-state Potts model on the square lattice
Shang-Wei Li, Kai-Wei Huang, Chien-Ting Chen et al. (+1 more)
The critical phenomena of 2D
antiferromagnetic $Q$-state Potts model on the square
lattice with $Q=2,3,4,5$ and 6 are investigated using supervised neural networks (NN). Conventional supervised and unsupervised NNs either fail or have difficulty in identifying the correct critical behaviors of these models. Remarkably, despite the fact that the NNs employed here are trained with a particular fixed type training set which contains no information about the considered models (except for $Q=2$), they correctly compute the critical temperatures for the studied physical systems. Particularly, the NN outcomes suggest convincingly that the $Q=3$ model is critical only at zero temperature and $Q=4,5,6$ models remain disordered at all temperatures. Apart from the studied models, our NNs trained with exactly the same training set have successfully determined the critical temperature(s) and the nature of the associated phase transition(s) of another physical system differing dramatically from those considered here. Therefore, our NN has the potential to be a universally applicable NN model in studying phase transitions.
Read the full abstract ▾
All authors Shang-Wei Li, Kai-Wei Huang, Chien-Ting Chen, Fu-Jiun Jiang
Materials Science
Does Fermi Level Alignment Hold Across Organic Interfaces? – An Investigation Using a Rotary Kelvin Probe
Masahiro Ohara, Taiyo Inoue, Yuya Tanaka et al. (+1 more)
Understanding energy level
alignment at organic interfaces is crucial for optimizing the performance of organic devices. Interface dipole and band bending significantly influence carrier recombination and generation mechanisms. A method of simulating energy level
alignment at metal/organic and organic/organic interfaces by assuming a thermal
equilibrium model has been proposed, but its validation against experimental methods is still limited. In this study, the work function change in the $\alpha$-NPD/HAT-CN/Au interface was measured as a typical donor/acceptor system using a rotary Kelvin probe (RKP). Our findings demonstrate good agreement with simulations only at metal/organic interfaces which have "active" charge transfer. It is suggested that thermal
equilibrium is not achieved simply by depositing the film under dark condition, and some treatment to supply carriers, such as exposure to UV light, is necessary for accurate evaluation. At the organic/organic interface, the the experimental results did not agree with thermal
equilibrium model, highlighting the need to consider substrate-driven carrier supply and polarization effects when evaluating energy level
alignment.
Read the full abstract ▾
All authors Masahiro Ohara, Taiyo Inoue, Yuya Tanaka, Hisao Ishii