Statistical Mechanics
Explosive connectivity and mechanical rigidity in cubic lattice structures
Trenton Lau and Gary P. T. Choi
We study explosive connectivity and mechanical
rigidity in three-dimensional cubic
lattice structures under Achlioptas-type product-rule dynamics. Our work combines extensive numerical simulation with a theoretical framework based on rigorous finite-size scaling. Using massive-scale simulations up to $L=192$ ($N \approx 7 \times 10^6$) with 20,000 independent realizations, we demonstrate that for $k \ge 8$, the peak susceptibility scales with an exponent of $\gamma = 1.000$, and the maximum single-step jump stabilizes at a macroscopic fraction. This confirms that while the transition is continuous in the infinite thermodynamic limit, it exhibits the exact finite-size scaling signatures of a first-order discontinuity in finite physical systems. For
rigidity, we discover numerically that for richly-connected hosts, increasing the number of choices $k$ optimally enhances the efficiency of rigidification. To explain this phenomenon, we propose a theoretical model centered on a conditional progress function that links an edge's local product-rule score to its global mechanical utility. We show that while local rigidification efficiency monotonically increases, the global
rigidity gap exhibits a “Goldilocks” minimum at intermediate $k$ due to the emergence of maximally floppy, tree-like components at large $k$. Altogether, our work provides new insights into the relationship between local dynamics and global connectivity and
rigidity in cubic
lattice structures via both theory and computation.
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Mesoscale and Nanoscale Physics
Machine-learned tuning to protected states by probing noise resilience
Rodrigo A. Dourado, Nicolás Martínez-Valero, Jacob Benestad et al. (+3 more)
Protected states are promising for
quantum technologies due to their intrinsic resilience against noise. However, such states often emerge at discrete points or small regions in parameter space and are thus difficult to find in experiments. In this work, we present a machine-learning method for tuning to protected regimes, based on injecting noise into the system and searching directly for the most noise-resilient configuration. We illustrate this method by considering short
quantum dot-based Kitaev chains which we subject to random parameter fluctuations. Using the covariance
matrix adaptation evolutionary strategy we minimize the typical resulting ground state splitting, which makes the system converge to a protected configuration with well-separated Majorana bound states. We verify the robustness of our method by considering finite Zeeman fields, electron-electron repulsion, asymmetric couplings, and varying the length of the Kitaev chain. Our work provides a reliable method for tuning to protected states, including but not limited to isolated Majorana bound states.
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All authors Rodrigo A. Dourado, Nicolás Martínez-Valero, Jacob Benestad, Martin Leijnse, Jeroen Danon, Rubén Seoane Souto
Quantum Gases · Cross-listed from nlin.PS
Multidimensional Soliton Systems: an Update
Boris A. Malomed
A briefly formulated update of the recently published review [1] on the topic of multidimensional
solitons (chiefly, in nonlinear optics and atomic Bose-Einstein condensates (BECs)) is presented. The update briefly summarizes some notable results on this topic that have been reported very recently, and offers a compact outline of the directions of the current experiment and theoretical work in this and related fields. In particular, as concerns newest experimental findings, included are the creation of multiple
quantum droplets in prolate BEC, and the observation of expanding toroidal light structures in linear optics. The update of theoretical results includes the analysis of 2D
solitons in the optical system with the quadratic nonlinearity and fractional diffraction, and the prediction of stable 3D
vortex solitons in various BEC schemes with long-range interactions.
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Materials Science
Automated Workflow for Non-Empirical Wannier-Localized Optimal Tuning of Range-Separated Hybrid Functionals
Stephen E. Gant, Francesco Ricci, Guy Ohad et al. (+3 more)
We introduce an automated workflow for generating non-empirical Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functionals. WOT-SRSH functionals have been shown to yield highly accurate fundamental band gaps, band structures, and optical spectra for bulk and 2D
semiconductors and
insulators. Our workflow automatically and efficiently determines the WOT-SRSH functional parameters for a given
crystal structure and composition, approximately enforcing the correct screened long-range Coulomb interaction and an ionization potential ansatz. In contrast to previous manual tuning approaches, our tuning procedure relies on a new search
algorithm that only requires a few hybrid functional calculations with minimal user input. We demonstrate our workflow on 23 previously studied
semiconductors and
insulators, reporting the same high level of accuracy. By automating the tuning process and improving its computational efficiency, the approach outlined here enables applications of the WOT-SRSH functional to compute spectroscopic and optoelectronic properties for a wide range of materials.
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All authors Stephen E. Gant, Francesco Ricci, Guy Ohad, Ashwin Ramasubramaniam, Leeor Kronik, Jeffrey B. Neaton
Statistical Mechanics · Cross-listed from physics.comp-ph
A fast and rigorous numerical tool to measure length-scale artifacts in molecular simulations
Benedikt M. Reible, Nils Liebreich, Carsten Hartmann et al. (+1 more)
The two-sided Bogoliubov inequality for classical and
quantum many-body systems is a
theorem that provides rigorous bounds on the free-energy cost of partitioning a given system into two or more independent subsystems. This
theorem motivates the definition of a quality factor which directly quantifies the degree of statistical-mechanical consistency achieved by a given simulation box size. A major technical merit of the
theorem is that, for systems with two-body interactions and a known radial distribution function, the quality factor can be computed by evaluating just two six-dimensional integrals. In this work, we present a numerical
algorithm for computing the quality factor and demonstrate its consistency with respect to results in the literature obtained from simulations performed at different box sizes.
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All authors Benedikt M. Reible, Nils Liebreich, Carsten Hartmann, Luigi Delle Site
Superconductivity · Cross-listed from quant-ph
Fast and Robust Remote Two-Qubit Gates on Distributed Qubits
Yunan Li, Xi Zhang, Weixin Zhang et al. (+4 more)
Distributed
quantum computing offers a potential solution to the complexity of superconducting chip hardware layouts and error correction
algorithms. High-quality gates between distributed chips enable the simplification of existing error correction
algorithms. This article proposes and demonstrates a remote
quantum geometric gate scheme via parametric modulation. Our scheme inherits the intrinsic robustness of
geometric phases. Meanwhile, by employing gradient-based optimization
algorithms(Adaptive Moment Estimation) from deep learning, we design control waveforms that significantly suppress population leakage. We experimentally realize the rapid remote SWAP and $\sqrt{\text{SWAP}}$ gates with high fidelity, completing operation in about 30 ns. The gate error of SWAP ($\sqrt{\text{SWAP}}$) is 1.16% (0.91%) after excluding the effect of energy relaxation. The simulation demonstrate that this scheme can be implemented in the distributed chips connected by cables extending several meters. Our results highlight the effectiveness of the proposed protocol in enabling modular
quantum processors, offering a promising path toward the realization of fault-tolerant
quantum computation.
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All authors Yunan Li, Xi Zhang, Weixin Zhang, Ruonan Guo, Yu Zhang, Xinsheng Tan, Yang Yu
Materials Science
Pd/Cu single atom alloys for catalysis: from single crystalline to nanostructured model systems for highly selective butanol dehydrogenation
Philipp Haugg, Jan Smyczek, Carsten Schröder et al. (+5 more)
Heterogeneous catalysts based on Single Atom
Alloys (SAA) play a significant role in numerous technical processes. The fundamental working principles of these systems, however, remain poorly understood, especially the aspects related to the nanoscopic nature of bimetallic particles and the associated structure-reactivity relationships. In this study, we developed for the first time well-defined SAA catalysts consisting of Pd atomically dispersed in Cu nanoparticles prepared under ultra-high
vacuum (UHV) conditions on model Al2O3/NiAl(110) support. Employing a unique combination of surface sensitive techniques - scanning tunneling microscopy (STM), infrared reflection absorption spectroscopy (IRAS), molecular beams - and density functional theory (DFT) calculations, we performed detailed structural characterization of these systems at the microscopic level. We demonstrate that Pd disperses atomically in Cu nanoparticles and becomes partly negatively charged. Importantly, these Pd/Cu nanostructured systems show an outstanding catalytic performance in selective dehydrogenation of butanol and exhibit 100 % selectivity toward butanal over a broad range of Pd loadings - the property that cannot be reproduced employing simplified single crystalline Pd/Cu(111) counterparts. The developed approach for preparation and characterization of these nanostructured SAA-catalysts lays a foundation for further fundamental-level catalytic studies on this important class of materials and their rational design for practical applications.
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All authors Philipp Haugg, Jan Smyczek, Carsten Schröder, Paul Fröhlich, Paul Kohlmorgen, Stephan Appelfeller, Konstantin Neyman, Swetlana Schauermann
Materials Science
Raman Spectroscopy Insights into the Reorientational Dynamics of Polyanions in Solid Electrolytes
Jianghai Chen, Yu Yang, Ya Tang et al. (+2 more)
The interaction between cation
diffusion and polyanion rotational dynamics has garnered significant
attention, yet characterizing the rotational dynamics of polyanions remains challenging. Previous studies have primarily relied on complex techniques such as
Nuclear Magnetic Resonance and Quasi-Elastic
Neutron Scattering. In this work, we use ab initio molecular dynamics (AIMD) simulations and temperature-dependent Raman spectroscopy to investigate the reorientational dynamics of the NO2- polyanion in Na3ONO2 and NaNO2. Our findings reveal distinct reorientational behaviors and establish a clear correlation between molecular reorientation and Raman spectral features in polyanion-based solid electrolytes. AIMD simulations show that NO2- rotates easily in Na3ONO2, while its rotational dynamics are hindered in NaNO2. Raman spectroscopy confirms these results, with temperature-dependent shifts in the internal vibrational modes of the polyanion. In Na3ONO2, the full width at half maximum (FWHM) of these modes increases with temperature, while NaNO2 exhibits a constant FWHM until a significant jump at the ordered-disordered phase transition. These insights enhance our understanding of polyanion reorientation and offer a framework for characterizing similar dynamics in other solid electrolytes.
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All authors Jianghai Chen, Yu Yang, Ya Tang, Hong Zhu, Wenqian Chen
Materials Science
Low-field magnetization processes of hexagonal easy-plane altermagnet $\alpha$-MnTe
Sahana Rößler, Victoria Ginga, Marcus Schmidt et al. (+5 more)
Single
crystals of $\alpha$-MnTe were synthesized by chemical vapor transport using iodine as the transport reagent. Structural characterization by powder x-ray diffraction confirmed the hexagonal structure (space group P6$_{3}$/mmc). Magnetization $M(T)$ and specific heat $C_p(T)$ measurements revealed an
antiferromagnetic phase transition at $T_N \approx307$ K. The
magnetic entropy derived from the $C_p(T)$ data is consistent with the $S = 5/2$
spin state of Mn$^{2+}$ ions. Angle- and field-dependent magnetization measurements indicate complex
magnetic responses associated with domains, and show an anomaly around 1 T. These features are analyzed using a phenomenological micromagnetic model that includes higher-order anisotropic exchange interactions coupling the weak
ferromagnetic component and the
antiferromagnetic order parameter. The model captures the generic behavior of
magnetic states and demonstrates that the observed uniaxial and unidirectional anisotropies arise from metastable domain configurations and irreversible magnetization processes.
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All authors Sahana Rößler, Victoria Ginga, Marcus Schmidt, Yurii Prots, Helge Rosner, Ulrich Burkhardt, Ulrich K. Rößler, Alexander A. Tsirlin
Soft Condensed Matter
Building granular structures with elasto-active systems
Yuchen Xi, Tom Marzin and P.-T. Brun
Natural active systems routinely reshape and reorganize their environments through sustained local interactions. Examples of decentralized collective construction are common in nature, e.g., many insects achieve large-scale constructions through indirect communication. While synthetic realizations of self-organization exist, they typically rely on rigid
agents that require some kind of sensors and direct programming to achieve their function. Understanding how soft, deformable active matter navigates and remodels crowded landscapes remains an open challenge. Here we show that connecting rigid microbots to elastic beams yields elasto-active structures that can restructure and adapt to heterogeneous surroundings. We investigate the dynamics of these
agents in environments with varying granular densities, rationalizing how they can aggregate or carve the medium through gentle interactions. At low density, the system compacts dispersed obstacles into clusters, a process modeled by a modified Smoluchowski coagulation theory. At high density, our
agents carve voids whose size is predicted by a force-limited argument. These results establish a framework for understanding how activity, elasticity, and deformability can influence active
navigation and environmental reconfiguration in granular media.
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Materials Science
Intertwined Hyperferroelectricity, Tunable Multiple Topological Phases and Giant Rashba Effect in Wurtzite LiZnAs
Saurav Patel, Paras Patel, Shaohui Qiu et al. (+1 more)
Composite
quantum compounds offer a fertile ground for uncovering the complex interrelations between seemingly distinct phenomena in condensed matter physics for advanced nonvolatile and spintronics applications. Beyond topological
superconductors and
axion insulators, the idea of intertwined Hyperferroelectricity (HyFE), multiple topological phases and Rashba
spin-splitting with reversible
spin textures represents the local, global and
symmetry-driven characteristics of
quantum materials, respectively, offering unique pathways for enhanced functionalities. We unveiled a unified framework to achieve this synergy through the presence of crystalline
symmetries and
spin-orbit coupling in LiZnAs compound using first-principles calculations. HyFE exhibits ability to maintain spontaneous polarization under open-
circuit boundary conditions, even with existence of depolarization field while Rashba effect exhibits paradigmatic
spin texture in momentum space with tangential vector field. The presence of unstable $A_{2u}(LO)$ mode leads to free energy minimum with significant well depth and polarization of -66 meV and $P_{HyFE} = 0.282~C/m^2$, respectively indicating stable HyFE. The robust HyFE stem from mode-specific effective charges and larger high-frequency dielectric constants. This study also addresses the subtle question of whether critical point of topological phase transition shifts in response to drastically different Rashba
spin-splitting values obtained from VASP and WIEN2k. Moreover, biaxial strain (BAS) induced Weyl semimetal (at 3.4% BAS) and topological insulating phase (after 3.4% BAS) is observed with
giant Rashba coefficient of 5.91 eV Å and 2.42 eV Å, respectively. Furthermore, switching of bulk polarization leads to
spin texture reversal, providing a robust mechanism to leverage
spin degrees of freedom in these Hyperferroelectric Rashba topological materials.
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All authors Saurav Patel, Paras Patel, Shaohui Qiu, Prafulla K. Jha
Superconductivity
Experimental signature of transient symmetry breaking in a cavity superconductor
Siyu Duan, Jingbo Wu, Xiaoqing Jia et al. (+5 more)
Transient states of matter far from
equilibrium may exhibit physical properties beyond those allowed by the
equilibrium-state crystalline
symmetries. We explore ultrafast and direct electronic excitations of transient states in a cavity
superconductor by using time-resolved terahertz-pump terahertz-probe spectroscopy. Our results show that the strong terahertz field can transiently modify the
symmetries of the electronic subsystems via the injection of a transient supercurrent, leading to high-order nonlinear dynamical responses that are not compatible with the
equilibrium-state
symmetries, which evidences for transient
symmetry breaking on the picosecond time scale. Our study also finds that the strong coupling of the
superconductor to the designed microcavities enables the sensitive detection of the nonlinear responses associated to the transient
symmetry breaking.
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All authors Siyu Duan, Jingbo Wu, Xiaoqing Jia, Huabing Wang, Ilya M. Eremin, Götz S. Uhrig, Biaobing Jin, Zhe Wang
Mesoscale and Nanoscale Physics
Robust structural superlubricity of twisted graphene bilayer and domain walls between commensurate moiré pattern domains from first-principles calculations
Irina V. Lebedeva, Andrey M. Popov, Yulia G. Polynskaya et al. (+3 more)
Twisted
graphene layers exhibit extremely low friction for relative sliding. Nevertheless, previous studies suggest that the area contribution to friction for commensurate moiré systems is finite and might restrict macroscopic superlubricity for large layer overlaps. In this paper, we investigate the potential energy surface (PES) for relative displacement of the layers forming moiré patterns (2,1) and (3,1) by accurate density functional theory calculations using the vdW-DF3 functional. The amplitudes of PES corrugations on the order of 0.4 and 0.03 $\mu$eV per atom of one layer, respectively, are obtained. The account of structural relaxation doubles this value for the (2,1) pattern, while causing only minimal changes for the (3,1) pattern. We show that different from aligned
graphene layers, for moiré patterns, PES minima and maxima can switch their positions upon changing the interlayer distance. The PES shape is closely described by the first spatial
Fourier harmonics both with and without account of structural relaxation. A barrier for relative rotation of the layers to an incommensurate state that can make superlubricity robust is estimated based on the approximated PES. We also derive a set of measurable physical properties related to interlayer interaction including shear mode frequency, shear modulus and static friction force. Furthermore, we predict that it should be possible to observe domain walls separating commensurate domains, each comprising a large number of moiré pattern unit
cells, and provide estimates of their characteristics.
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All authors Irina V. Lebedeva, Andrey M. Popov, Yulia G. Polynskaya, Andrey A. Knizhnik, Sergey A. Vyrko, Nikolai A. Poklonski
Mesoscale and Nanoscale Physics
Large-Area Atomically Flat Monocrystalline Gold Flakes: Recent Advances, Applications, and Future Potential
Amro O. Sweedan, Kefan Zhang, Muhammad Y. Bashouti et al. (+1 more)
High aspect ratio oblate polygonal gold
crystals - such as triangular and hexagonal platelets - have attracted considerable interest due to their extraordinary physical, chemical, and mechanical properties. Commonly referred to as "gold flakes," these structures exhibit atomically flat surfaces, $\mu$m$^2$ areas with nanometric thickness, and a monocrystalline morphology. Since their first discovery by John Turkevich in 1951, considerable progress has been made in shape-controlled synthesis and large-scale production, unlocking steadily new opportunities for ever more advanced applications. This review explores large-area gold flakes with lateral dimensions spanning from hundreds of nanometers to millimeters, emphasizing their unique properties. We provide a comprehensive overview of key developments, from early discoveries, synthesis approaches, and fabrication techniques to recent breakthroughs. Emphasis is placed on the integration of gold flake as functional building blocks in photonics (e.g., for nanoantennas), sensing, nanoelectronics, biomedicine, and beyond. We conclude with a discussion of emerging roles and future developments of this unique class of materials.
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All authors Amro O. Sweedan, Kefan Zhang, Muhammad Y. Bashouti, Thorsten Feichtner
Mesoscale and Nanoscale Physics
Local thermodynamic DOS measurement and twist-angle mapping in graphene-hBN superlattices
Namkyung Lee, Hangyeol Park, Seungwon Jung et al. (+3 more)
Moiré patterns arising from twisted van der Waals stacks fundamentally reshape their electronic properties, enabling band-structure engineering that has driven rapidly growing interest in this field. In studying electronic properties, however, structural disorder present in real devices often leads to twist-angle inhomogeneity and obscures angle-dependent electronic effects when measured with bulk-averaged measurements. Probes that can access local thermodynamic response of the electronic systems with high sensitivity would be highly valuable. Here, we adopt Kelvin probe force microscopy (KPFM) to locally investigate
graphene-hBN superlattices. By additionally modulating the chemical potential of the system, we obtain the inverse compressibility with high signal-to-noise ratio, enabling extraction of the local thermodynamic DOS. From this information, we determine the local twist angle along the device and find that twist-angle deviations are strongly correlated with bubble-induced strain features. Furthermore, by simultaneously tracking the offsets in the contact potential difference and in the net charge, we identify which interface within the
heterostructure hosts the trapped bubbles. This capability to identify local electro-chemical environments provides a practical tool for strain-based studies and future device designs utilizing nanoscale engineering in moiré systems.
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All authors Namkyung Lee, Hangyeol Park, Seungwon Jung, Baeksan Jang, Seonyu Lee, Joonho Jang
Materials Science
Switchable Polarization in an A-site Deficient Perovskite through Vacancy and Cation Engineering
Suguru Yoshida, Olivier Hernandez, Jinsuke Miyake et al. (+7 more)
While defects are unavoidable in
crystals and often detrimental to material performance, they can be a key ingredient for inducing functionalities when tailored. Here, we demonstrate that an A-site-deficient perovskite Y$_{1/3}$TaO$_3$ exhibits room-temperature ferroelectricity in a $Pb2_1m$ phase, enabled by ordered vacancies coupled with TaO$_6$ octahedral rotations. Defect-ordered perovskites are frequently trapped in centrosymmetric incommensurate states due to competing structural instabilities; we circumvent this by favoring rotational over polar instability through compositional selection. Unlike canonical improper ferroelectrics that are ferrielectric, the vanishing dipoles on vacancy layers in Y$_{1/3}$TaO$_3$ allow for a net ferroelectric
alignment of local dipoles, resulting in enhanced polarization. Upon heating, Y$_{1/3}$TaO$_3$ transforms to a paraelectric incommensurate phase at $\simeq$750 K, whose atomic arrangement mirrors the domain
topology observed in hybrid improper ferroelectrics. Superspace analysis of the modulated phase reveals a route to improve room-temperature polarization, achieved through epitaxial strain, as confirmed by our
lattice-dynamics calculations. This defect-ordering strategy should be generalizable to other improper ferroelectrics, including magnetoelectric multiferroics, providing a pathway to amplify otherwise limited macroscopic polarization.
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All authors Suguru Yoshida, Olivier Hernandez, Jinsuke Miyake, Kei Nakayama, Ryo Ishikawa, Hajime Hojo, Yuichi Ikuhara, Venkatraman Gopalan, Katsuhisa Tanaka, Koji Fujita
Materials Science
Orbital magnetization in the Nb-substituted Kagome metal CsV$_3$Sb$_5$
H.J. Elmers, O. Tkach, Y. Lytvynenko et al. (+12 more)
This study uses angle-resolved photoemission spectroscopy to examine the low-temperature electronic structure of Cs(V$_{0.95}$Nb$_{0.05}$)$_3$Sb$_5$, demonstrating that partially substituting V atoms with isoelectronic Nb atoms results in \blue{an increase of the band width} and enhanced gap opening at the Dirac-like crossings due to the resulting chemical pressure. This increases the
magnetic circular dichroism signal in the angular distribution (MCDAD) compared to CsV$_3$Sb$_5$, enabling detailed analysis of
magnetic circular dichroism in several bands near the
Fermi level. These results \blue{substantiate} the predicted coupling of orbital
magnetic moments to three van Hove singularities near the
Fermi level at M points. Previous studies have observed that Nb doping \blue{lowers the charge density transition temperature} and increases the critical temperature for superconductivity. This article demonstrates that Nb doping concomitantly increases the
magnetic circular dichroism signal attributed to orbital moments.
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All authors H.J. Elmers, O. Tkach, Y. Lytvynenko, H. Agarwal, D. Biswas, J. Liu, A.-A. Haghighirad, M. Merz, S. Pakhira, G. Garbarino, T.-L. Lee, J. Demsar, G. Schonhense, M. Le Tacon, O. Fedchenko
Mesoscale and Nanoscale Physics
Interaction of moire-induced quantum Hall channels in a locally gated graphene junction
Won Beom Choi, Myungjin Jeon, K. Watanabe et al. (+2 more)
Manipulating electron
quantum 1D channels is an important element in the field of
quantum information due to their ballistic and phase coherence properties. In GaAs and
graphene based two dimensional gas systems, these edge channels have been investigated with both integer and fractional
quantum Hall effects, contributing to the realization of electron interferometer and anyon braiding. Often, at the p-n junction in the
quantum Hall (QH) regime, the presence of a depletion region due to a band gap or the formation of gaps between the zeroth Landau levels (zLL) suppresses interaction between the co-propagating edge channels of opposing doping regimes and helps to preserve the phase coherence of the channels. Here, we observe a new type of p-n junction in hexagonal boron nitride aligned
graphene that lacks both the zLL and band gap. In this system, a van Hove singularity (vHS) emerges at the p-n junctions under
magnetic fields of several Tesla, owing to the doping inversion near the secondary Dirac point. By fabricating devices with independently tunable global bottom and local top gates, we enable the study of interactions between p-type and n-type QH edge channels through
magnetic breakdown associated with the vHS. These findings provide valuable insights into the interactions of superlattice-induced QH edge channels in hBN-aligned
graphene.
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All authors Won Beom Choi, Myungjin Jeon, K. Watanabe, T. Taniguchi, Joonho Jang
Soft Condensed Matter
Rheological Behavior of Colloidal Silica Dispersion: Irreversible Aging and Thixotropy
Vivek Kumar and Yogesh M. Joshi
In this work, we study the rheological behavior of colloidal dispersion of charge-screened nanoparticles of silica suspended in aqueous media that exhibits soft solid-like consistency. We observe that the system shows various characteristics of physical aging wherein it undergoes time
evolution of rheological properties such as elastic modulus, relaxation time, and yield stress subsequent to shear melting of the same. Notably, the relaxation time increases more strongly than linearly with time, which is suggestive of hyper-aging dynamics. When considered along with the time-dependent yield stress, this behavior indicates the steady state shear stress-shear rate flow curve to be non-monotonic with a negative slope in a lower shear rate region. Performing shear melting on this system at a later date since the preparation of the dispersion (rest time) results in higher viscosity as well as yield stress, and the corresponding
evolution of the elastic modulus shifts to lower times. This implies that physical aging in studied silica dispersion, while reversible over short time scales (of the order of hours), becomes irreversible over longer durations (days) owing to the inability of strong shear to break interparticle bonds that have strengthened over long durations. We also develop a thixotropic structural kinetic model within a time-dependent Maxwell framework that captures the experimentally observed rheological behavior well.
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Materials Science
Haidong Liang, Ganesh Ji Omar, Kun Han et al. (+3 more)
The interfacial electronic properties of complex
oxides are governed by a delicate balance between charge transfer,
lattice distortions, and electronic correlations, posing a key challenge for controlled tunability in materials research. Here, we demonstrate that
proton implantation serves as a precise tool for modulating interfacial transport in SrTiO3-based
heterostructures. By introducing
protons into the SrTiO3 substrate beneath an amorphous (La,Sr)(Al,Ta)O3 capping layer, we uncover a competition between disorder and charge doping induced by implantation. At low implantation fluences below 1x1015
protons/cm2 (1E15), charge doping dominates, leading to an increase in carrier density and mobility, analogous to electrostatic gating effect. This enables the emergence of
quantum transport oscillations at low temperature. Conversely, at higher fluences (above 1E15), disorder scattering prevails, suppressing carrier mobility and inducing an insulating state. The nonmonotonic
evolution of transport with implantation fluence underscores the critical interplay between electronic correlations and disorder, offering a new paradigm for the controlled engineering of interfacial
quantum states in SrTiO3-based
oxide heterostructures.
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All authors Haidong Liang, Ganesh Ji Omar, Kun Han, Andrew A. Bettiol, Zhen Huang, A. Ariando
Materials Science
Strong coupling between coherent ferrons and cavity acoustic phonons
Yujie Zhu, Jiaxuan Wu, Anna N. Morozovska et al. (+7 more)
Coherent ferrons, the quanta of polarization waves, can potentially be hybridized with many other quasiparticles for achieving novel control modalities in
quantum communication, computing, and sensing. Here, we theoretically demonstrate a new hybridized state resulting from the strong coupling between fundamental-mode (wavenumber is zero) coherent ferrons and cavity bulk acoustic
phonons. Using a van der Waals ferroelectric CuInP2S6 membrane as an example, we predict an ultra-strong ferron-
phonon coupling at room temperature, where the coupling strength g_c reaches over 10% of the resonant frequency {\omega}_0. We also predict an in-situ bistable electric-field control of mode-specific ferron-
phonon hybridization via ferroelectric switching. We further show that CuInP2S6 allows for reaching the fundamentally intriguing but challenging deep strong coupling regime (i.e., g_c/{\omega}_0>1) near the ferroelectric-to-paraelectric phase transition. Our findings establish the theoretical basis for exploiting coherent ferron as a new contender for hybrid
quantum system with strong and highly tunable coherent coupling
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All authors Yujie Zhu, Jiaxuan Wu, Anna N. Morozovska, Eugene A. Eliseev, Yulian M. Vysochanskii, Venkatraman Gopalan, Long-Qing Chen, Xufeng Zhang, Wei Zhang, Jia-Mian Hu
Mesoscale and Nanoscale Physics
Interference dislocations adjacent to emission spot
J. R. Leonard, L. H. Fowler-Gerace, Zhiwen Zhou et al. (+3 more)
We studied interference dislocations (forks) adjacent to an emission spot in an interference pattern. The adjacent interference dislocations are observed in emission of
excitons in a monolayer transition metal dichalcogenide and in emission of spatially indirect
excitons, also known as interlayer
excitons, in a van der Waals
heterostructure. The simulations show that the adjacent interference dislocations appear due to the moiré effect in combined interference patterns produced by constituting parts of the emission spot. The adjacent interference dislocations can appear in interference images for various spatially modulated emission patterns.
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All authors J. R. Leonard, L. H. Fowler-Gerace, Zhiwen Zhou, E. A. Szwed, D. J. Choksy, L. V. Butov
Statistical Mechanics
Parastatistics in Interacting Periodic Chains Revealed by Peierls Phase Twists and Shifted Conformal Towers
D. Schuricht and J. Sirker
We consider interacting paraparticle chains with a constant $R$-
matrix where the
Hamiltonian sums over the internal degrees (
flavors) of the paraparticles. For such
flavor-blind
Hamiltonians we show a general factorization of the
Hilbert space into occupation and
flavor parts with the
Hamiltonian acting non-trivially only on the former. For open boundaries, the spectrum therefore coincides with that of the occupation
Hamiltonian $H_{\rm occ}$ with the
flavor part merely adding degeneracies. For periodic boundaries, a cyclic reordering of the
flavors leads to a separation of $H_{\rm occ}$ into flux sectors at fixed particle number, thus making the parastatistics directly observable in the energy spectrum. For important exemplary cases, $H_{\rm occ}$ reduces to the XXZ chain with flux allowing for an exact solution. In the gapless regime, this solution shows flux-shifted $c=1$ conformal towers in the low-energy spectrum and a temperature-dependent chemical potential in the bulk thermodynamics.
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Superconductivity
Novel $H_{\rm c2}$ suppression mechanism in a spin triplet superconductor – Application to UTe$_2$–
Kazushige Machida
A novel $H_{\rm c2}$ suppression mechanism is theoretically proposed in a
spin triplet
superconductor (SC) with equal
spin pairs. We show that the upper critical field $H_{\rm c2}$ can be reduced from the orbital depairing limit $H^{\rm orb}_{\rm c2}$ to arbitrarily small value, keeping the second order phase transition nature. This mechanism is sharply different from the known Pauli-Clogston limit for a
spin singlet SC where the reduction is limited to $\sim$0.3$H^{\rm orb}_{\rm c2}$ with the first order transition when the Maki parameter goes infinity. This novel $H_{\rm c2}$ suppression mechanism is applied to UTe$_2$, which is a
prime candidate for a
spin triplet SC, to successfully analyze the $H_{\rm c2}$ data for various crystalline orientations both under ambient and applied pressure, and to identify the pairing
symmetry. It is concluded that the non-
unitary spin triplet state with equal
spin pairs is realized in UTe$_2$, namely $(\hat b+i\hat c)k_a$ in $^3$B$_{\rm 3u}$ which is classified under finite
spin orbit coupling scheme.
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Quantum Gases
Enhanced performance of sudden-quench quantum Otto cycles via multi-parameter control
Raymon S. Watson and Karen V. Kheruntsyan
Advances in experimental control of interacting
quantum many-body systems with multiple tunable parameters-such as ultracold atomic gases and trapped ions-are driving rapid progress in
quantum thermodynamics and enabling the design of
quantum thermal machines. In this work, we utilize a sudden quench approximation as a means to investigate the operation of a
quantum thermodynamic Otto cycle in which multiple parameters are simultaneously controllable. The method applies universally to many-body systems where such control is available, and therefore provides general principles for investigating their operation as a working medium in
quantum thermal machines. We investigate application of this multi-parameter quench protocol in an experimentally realistic one-dimensional Bose gas, as well as in the transverse-field Ising model. We find that such a multi-parameter Otto cycle, when operating as an engine, outperforms not only its constituent single-parameter Otto cycles in terms of the net work and efficiency, but also the combined net work of its constituent engine cycles when added together independently. We also find that a similar multi-parameter enhancement applies to the coefficient of performance when the Otto cycle operates as a refrigerator.
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Materials Science
Outstanding figure of merit at high temperature for DFT-based predicted double perovskite oxides, Ba2GaXO6 (X = V, Nb, Ta)
S. S. Saif, M. M. Hossain and M. A. Ali
Thermoelectric materials with a high figure of merit (ZT) are highly demanded for a sustainable solution to the energy crisis. In this study, we have predicted three new double perovskite
oxides (DPOs), Ba2GaXO6 (X = V, Nb, Ta), with high ZT values using density functional theory (DFT) calculations and investigated their structural, electronic, thermoelectric, and mechanical properties. The electronic properties, such as electronic band structure, density of states (DOS), and charge density mapping, are used to disclose the conductive nature, chemical bonding within these compounds, which exhibit direct band gaps of 0.924, 2.354, and 3.279 eV for Ba2GaVO6, Ba2GaNbO6, and Ba2GaTaO6, respectively, as calculated using the TB mBJ potential. The thermoelectric performance of the new DPOs, Ba2GaXO6 (X = V, Nb, Ta), was assessed using the BoltzTrap2 code, which yielded outstanding ZT values of 2.36, 1.78, and 1.91 at 1500 K for Ba2GaVO6, Ba2GaNbO6, and Ba2GaTaO6, respectively, indicating their potential for waste heat management. The high ZT values are attributed to an ultra low
lattice thermal conductivity, arising from strong scattering of acoustic and optical
phonon modes. The changes in thermoelectric parameters with temperature were analyzed and explained.
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