Condensed Matter

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New submissions for Thu, 2 May 24

[1]  arXiv:2405.00049 [pdf, ps, other]

Title: Role of stress/strain in tailoring the magnetic and transport properties of magnetic thin films and multilayers

Authors: Arun Singh Dev, Dileep Kumar

Subjects: Materials Science (cond-mat.mtrl-sci)

Magnetic anisotropy is a fundamental property of magnetic materials that determines the alignment of the spins along the preferential direction, called the easy axis of magnetization. Magnetic polycrystalline thin films offer several advantages over magnetic epitaxial thin films because of fabrication flexibility, higher coercivity and improved magnetic stability, higher magnetoresistance (useful in magneto-resistive devices such as magnetic field sensors and MRAM cells), cost-effectiveness and thermal stability, etc. In the case of polycrystalline thin films or multilayers, Magneto-crystalline anisotropy (MCA) is not expected due to the random orientation of grains. Therefore, understanding the origin of uniaxial magnetic anisotropy (UMA) is generally difficult and can't be understood in terms of crystal orientation. The origin of UMA in polycrystalline films is often related to the preparation conditions and substrate properties. In the present thesis, we have provided direct in-situ real-time evidence of the stress dependence of magnetic anisotropy through the multibeam optical stress sensor (MOSS) technique. Also, we have tuned the magnetic anisotropy in strength and direction using externally applied stress. To further increase the strength of the magnetic anisotropy, we have developed a new technique that creates a multilayer using a single magnetic material through sequential oblique and normal depositions. This oblique angle deposition technique also helps reduce the penetration of the top ferromagnetic layer inside the organic semiconductor layer in organic spin valve structures. We confirm our results through various in-situ (in UHV and HV) and ex-situ temperature-dependent conventional and unconventional structural, morphological, and magnetic measurements (both lab-based and synchrotron-based) that include MOKE, KERR, GIXRD, AFM, RHEED, and GISAXS, etc. measurements.

[2]  arXiv:2405.00057 [pdf, other]

Title: Microstructural and Transport Characteristics of Triply Periodic Bicontinuous Materials

Authors: Salvatore Torquato, Jaeuk Kim

Comments: 16 pages, 6 figures, and 5 tables

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

3D bicontinuous two-phase materials are increasingly gaining interest because of their unique multifunctional characteristics and advancements in techniques to fabricate them. Due to their complex topological and structural properties, it still has been nontrivial to develop explicit microstructure-dependent formulas to predict accurately their physical properties. A primary goal of the present paper is to ascertain various microstructural and transport characteristics of five different models of triply periodic bicontinuous porous materials at a porosity $\phi_1=1/2$: those in which the two-phase interfaces are the Schwarz P, Schwarz D and Schoen G minimal surfaces as well as two different pore-channel structures. We ascertain their spectral densities, pore-size distribution functions, local volume-fraction variances, and hyperuniformity order metrics and then use this information to estimate certain effective transport properties via closed-form microstructure-property formulas. Specifically, we estimate the recently introduced time-dependent diffusion spreadability exactly from the spectral density. Moreover, we accurately estimate the fluid permeability of such porous materials from the second moment of the pore-size function and the formation factor, a measure of the tortuosity of the pore space. We also rigorously bound the permeability from above using the spectral density. For the five models with identical cubic unit cells, we find that the permeability, inverse of the specific surface, hyperuniformity order metric, pore-size second moment and long-time spreadability behavior are all positively correlated and rank order the structures in exactly the same way. We also conjecture what structures maximize the fluid permeability for arbitrary porosities and show that this conjecture must be true in the extreme porosity limits by identifying the corresponding optimal structures.

[3]  arXiv:2405.00091 [pdf, other]

Title: Dipole-Obstructed Cooper Pairing: Theory and Application to $j=3/2$ Superconductors

Authors: Penghao Zhu, Rui-Xing Zhang

Comments: 6+9 pages, 3+5 figures

Subjects: Superconductivity (cond-mat.supr-con); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el)

Like electrons, Cooper pairs can carry a monopole charge if the pairing electrons come from two or more Fermi surfaces with different Chern numbers. In such an instance, a superconductor is necessarily nodal due to an inherent topological pairing obstruction. In this work, we show that a similar obstruction is also possible when there is only one Fermi surface involved in the pairing process. By developing a Chern-vorticity theorem, we have identified a class of Fermi surfaces with a quantized dipolar Berry flux pattern, where all intra-Fermi-surface Cooper pairings are ``dipole-obstructed" and nodal. As a real-world application, we find that the dipole obstruction plays a crucial role in stabilizing the superconducting nodal structure for $j=3/2$ half-Heusler compounds.

[4]  arXiv:2405.00092 [pdf, other]

Title: Type II t-J model in charge transfer regime in bilayer La$_3$Ni$_2$O$_7$ and trilayer La$_4$Ni$_3$O$_{10}$

Authors: Hanbit Oh, Boran Zhou, Ya-Hui Zhang

Comments: 7+10 pages, 3+9 figures, 0+1 table

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con)

Recent observations of an 80 K superconductor in La$_3$Ni$_2$O$_7$ under high pressure have attracted significant attention. Recent experiments indicate that La$_3$Ni$_2$O$_7$ may be in the charge transfer regime, challenging the previous models based purely on the Ni $d_{x^2-y^2}$ and $d_{z^2}$ orbitals. In this study, we propose a low energy model that incorporates doped holes in the oxygen $p$ orbitals. Given that the parent nickel state is in the $3d^{8}$ configuration with a spin-one moment, doped hole only screens it down to spin-half, in contrast to the Zhang-Rice singlet in cuprate. We dub the single hole state as Zhang-Rice spin-half and build an effective model which includes three spin-one states ($d^8$) and two Zhang-Rice spin-half states ($d^8 L$). At moderate pressure around $20$ GPa, the dominated oxygen orbital is an in-plane Wannier orbital with the same lattice symmetry as the $d_{x^2-y^2}$ orbital. The resulting model reduces to the bilayer type II t-J model previously proposed in the Mott-Hubbard regime. Notably, the hopping between the in-plane $p$ orbitals of the two layers is still suppressed. Density matrix renormalization group (DMRG) simulation reveals a pairing dome with the optimal hole doping level at $x=0.4\sim0.5$, distinct from the hole doped cuprate where optimal doping occurs around $x=0.19$. Further increasing pressure initially raises the critical temperature ($T_c$) until reaching an optimal pressure beyond which the $p_z$ orbital of oxygen becomes favorable and superconductivity is diminished. This shift from in-plane $p$ orbital to $p_z$ orbital may elucidate the experimentally observed superconducting dome with varying pressure. As an extension, we also suggest a trilayer version of the type II t-J model as the minimal model for pressured La$_4$Ni$_3$O$_{10}$, which is distinct from the models in the Mott-Hubbard regime.

[5]  arXiv:2405.00178 [pdf, ps, other]

Title: Quantum Entanglement In Mixed-Spin Trimmer: Effects of A Magnetic Field And Heterogeneous g-Factors

Authors: Zhirayr Adamyan, Vadim Ohanyan

Comments: 13 pages, 19 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech)

Mixed spin-(1/2,1/2,1) trimmer with two different Land\'{e} g-factors and two different exchange couplings is considered. The main feature of the model is non-conserving magnetization. The Hamiltonian of the system is diagonalized analytically. We presented a detailed analysis of the ground state properties, revealing several possible ground state phase diagrams and magnetization profiles. The main focus is on how non-conserving magnetization affects quantum entanglement. We have found that non-conserving magnetization can bring to the continuous dependence of the entanglement quantifying parameter (negativity) on magnetic field within the same eigenstate, while for the case of uniform $g$-factors it is a constant. The main result is an essential enhancement of the entanglement in case of uniform couplings for one pair of spins caused by an arbitrary small difference in the values of $g$-factors. This enhancement is robust and brings to almost 7-fold increasing of the negativity. We have also found weakening of entanglement for other cases. Thus, non-conserving magnetization offers a broad opportunity to manipulate the entanglement by means of magnetic field.

[6]  arXiv:2405.00192 [pdf, ps, other]

Title: A momentum-space theory for topological magnons in 2D ferromagnetic skyrmion lattices

Authors: Doried Ghader, Bilal Jabakhanji

Comments: Supplementary notes will be made available with the published version

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Magnon dynamics in skyrmion lattices have garnered significant interest due to their potential applications in topological magnonics. Existing theories often follow a single-momentum approach, assuming significant Dzyaloshinskii-Moriya Interaction (DMI) to minimize the skyrmion's dimensions, which can lead to oversimplification in describing magnon behavior. This study introduces a multi-momentum operator theory for magnons in large 2D skyrmions, where each skyrmion encompasses several thousand spins. The proposed theory fully transforms the magnon Hamiltonian into momentum space, incorporating off-diagonal terms to capture umklapp scattering caused by the skyrmion wave vectors. Our results reveal deviations from single-momentum theories, demonstrating that flat bands are not universal features of the skyrmionic magnon spectrum. Additionally, we find that manipulating the skyrmion size with an external magnetic field induces multiple topological phase transitions. At high magnetic fields, the low-energy magnon spectrum becomes densely packed and entirely topological, resembling a topological band continuum.

[7]  arXiv:2405.00195 [pdf, other]

Title: Room-temperature optomechanics with light-matter condensates

Authors: Vladislav Yu. Shishkov, Evgeny S. Andrianov, Anton V. Zasedatelev

Subjects: Quantum Gases (cond-mat.quant-gas)

In this work, we develop an optomechanical formalism for macroscopic quantum states in exciton-polariton systems with strong exciton-phonon interactions. We show that polariton optomechanical interactions induce dynamical backaction, resulting in dispersive and dissipative shifts in the complex vibrational response functions. Unlike conventional optomechanical systems, polariton optomechanics features high-dimensionality and phase-space confinement due to the dispersion relations of exciton-polaritons. Consequently, vibrational modes exhibit effective positive or negative mass depending on the detuning parameter, and are capable for the vibrational Bose condensation under the resonant conditions. We demonstrate the potential for vibrational control of polariton condensates at room temperature.

[8]  arXiv:2405.00210 [pdf, ps, other]

Title: Deposition of highly-crystalline AlScN thin films using synchronized HiPIMS -- from combinatorial screening to piezoelectric devices

Authors: Jyotish Patidar (1), Kerstin Thorwarth (1), Thorsten Schmitz-Kempen (2), Roland Kessels (2), Sebastian Siol (1) ((1) Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland (2) aixACCT Systems GmbH, Aachen, Germany)

Subjects: Materials Science (cond-mat.mtrl-sci)

Fueled by the 5G revolution, the demand for advanced radio frequency micro-electromechanical systems (MEMS) based on AlScN is growing rapidly. However, synthesizing high-quality, textured AlScN thin films is challenging. Current approaches typically rely on high temperatures and expensive compound targets. In this study, we demonstrate the feasibility of ionized physical vapor deposition to deposit highly oriented AlScN films with minimal defects at lower temperatures. Using metal-ion synchronized high-power impulse magnetron co-sputtering (MIS-HiPIMS) we can selectively bombard the growing film with Al and/or Sc ions to enhance the adatom mobility while simultaneously providing the ability to tune stress and coat complex structures conformally. We find that the Sc solubility in wurtzite AlN is slightly reduced, whereas crystallinity and texture are markedly improved. Disoriented grains, a key challenge in growing AlScN films, are completely removed via substrate biasing, while the residual stress can be tailored by adjusting the same. The measured piezoelectric response of the films is in line with DFT predictions and on par with the current state of the art. Finally, we demonstrate conformal deposition of c-axis textured AlScN on structured Si wafers underlining the promise of ionized PVD for the fabrication of advanced RF filters and next-generation MEMS devices.

[9]  arXiv:2405.00214 [pdf, ps, other]

Title: Analytical solutions of symmetric isotropic spin clusters

Authors: Shadan Ghassemi Tabrizi, Thomas D. Kühne

Comments: 23 pages, 5 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el)

Spin models like the Heisenberg Hamiltonian effectively describe the interactions of open-shell transition-metal ions on a lattice and can account for various properties of magnetic solids and molecules. Numerical methods are usually required to find exact or approximate eigenstates, but for small clusters with spatial symmetry, analytical solutions exist, and a few Heisenberg systems have been solved in closed form. This paper presents a simple, generally applicable approach to analytically solve isotropic spin clusters, based on adapting the basis to both total-spin and point-group symmetry to factor the Hamiltonian matrix into sufficiently small blocks. We demonstrate applications to small rings and polyhedra, some of which are straightforward to solve by successive spin-coupling for Heisenberg terms only; additional interactions, such as biquadratic exchange or multi-center terms necessitate symmetry adaptation.

[10]  arXiv:2405.00238 [pdf, other]

Title: Noise reduction by bias cooling in gated Si/SixGe1-x qunatum dots

Authors: Julian Ferrero, Thomas Koch, Sonja Vogel, Daniel Schroller, Viktor Adam, Ran Xue, Inga Seidler, Lars R. Schreiber, Hendrik Bluhm, Wolfgang Wernsdorfer

Comments: 11 pages, 8 figures, silicon, SiGe, heterostructure, bias cooling, experiment, simulation

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Silicon-Germanium heterostructures are a promising quantum circuit platform, but crucial aspects as the long-term charge dynamics and cooldown-to-cooldown variations are still widely unexplored quantitatively. In this letter we present the results of an extensive bias cooling study performed on gated silicon-germanium quantum dots with an Al2O3-dielectric. Over 80 cooldowns were performed in the course of our investigations. The performance of the devices is assessed by low-frequency charge noise measurements in the band of 200 micro Hertz to 10 milli Hertz. We measure the total noise power as a function of the applied voltage during cooldown in four different devices and find a minimum in noise at 0.7V bias cooling voltage for all observed samples. We manage to decrease the total noise power median by a factor of 6 and compute a reduced tunneling current density using Schr\"odinger-Poisson simulations. Furthermore, we show the variation in noise from the same device in the course of eleven different cooldowns performed under the nominally same conditions.

[11]  arXiv:2405.00290 [pdf, ps, other]

Title: Message-Passing Interatomic Potentials Learn Non-Local Electrostatic Interactions

Authors: Sungwoo Kang

Subjects: Materials Science (cond-mat.mtrl-sci)

This work demonstrates that E(3)-equivariant graph neural network interatomic potentials (GNN-IPs) effectively learn non-local electrostatic interactions and charge transfers. Using a toy model with point charges, it is confirmed that GNN-IPs adeptly interpolate and extrapolate electrostatic interactions, independent of geometric coupling. It is also found that the electrostatic energy between an atom pair is distributed among neighboring atoms, rather than localized solely within the two atoms involved. Furthermore, GNN-IPs have proven successful in capturing non-local interactions through charge transfer on density functional theory reference data, as evidenced by comparative analyses of the potential energy surfaces for Au clusters on both MgO and Al-doped MgO substrates.

[12]  arXiv:2405.00292 [pdf, other]

Title: Phase shifts, band geometry and responses in triple-Q charge and spin density waves

Authors: Ying-Ming Xie, Naoto Nagaosa

Comments: 6 pages, 3 figures, plus Supplementary Material

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el)

Recently, there has been growing interest in the impacts of phase shifts within the triple-Q spin density wave (SDW) order parameters. Concurrently, it is widely recognized that incommensurate triple-Q charge density waves (CDW) are also prevalent in low-dimensional materials, where the phase degrees of freedom in the order parameters are generally allowed. In this study, we systematically investigate the pivotal effects arising from both triple-Q CDW and SDW order parameters, with particular consideration given to possible phase shifts. We show that the phase shifts play a crucial role in determining the real-space topology of triple-Q density waves. More importantly, we show that the triple-Q CDW and SDW order parameters would influence the band geometry in the momentum space, where multiband Dirac-like fermions are induced by the triple-Q density wave order parameters near the Fermi energy. Furthermore, we explicitly establish that such nontrivial band geometry, combined with symmetry-breaking induced by phase shifts, leads to a variety of intriguing linear and nonlinear responses.

[13]  arXiv:2405.00299 [pdf, ps, other]

Title: Thermal stability and phase transformation of $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ thin films to $β$-Ga$_2$O$_3$ under various ambient conditions

Authors: J. Tang, K. Jiang, P. Tseng, R. C. Kurchin, L. M. Porter, R. F. Davis

Comments: 15 pages, 6 figures, 1 table

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

Phase transitions in metastable $\alpha$-, $\kappa(\epsilon)$-, and $\gamma$-Ga$_2$O$_3$ films to thermodynamically stable $\beta$-Ga$_2$O$_3$ during annealing in air, N$_2$, and vacuum have been systematically investigated via in-situ high-temperature X-ray diffraction and scanning electron microscopy. These respective polymorphs exhibited thermal stability to around 471-525$^\circ$C, 773-825$^\circ$C, and 490-575$^\circ$C before transforming into $\beta$-Ga$_2$O$_3$, across all tested ambient conditions. Particular crystallographic orientation relationships were observed before and after the phase transitions, i.e., (0006) $\alpha$-Ga$_2$O$_3$ $\parallel$ $(\overline{4}02)$ $\beta$-Ga$_2$O$_3$, (004) $\kappa(\epsilon)$-Ga$_2$O$_3$ $\parallel$ (310) and $(\overline{4}02)$ $\beta$-Ga$_2$O$_3$, and (400) $\gamma$-Ga$_2$O$_3$ $\parallel$ (400) $\beta$-Ga$_2$O$_3$. The phase transition of $\alpha$-Ga$_2$O$_3$ to $\beta$-Ga$_2$O$_3$ resulted in catastrophic damage to the film and upheaval of the surface. The respective primary and possibly secondary causes of this damage are the +8.6% volume expansion and the dual displacive and reconstructive transformations that occur during this transition. The $\kappa(\epsilon)$- and $\gamma$-Ga$_2$O$_3$ films converted to $\beta$-Ga$_2$O$_3$ via singular reconstructive transformations with small changes in volume and unchanged surface microstructures.

[14]  arXiv:2405.00306 [pdf, other]

Title: Environment-adaptive machine learning potentials

Authors: Ngoc Cuong Nguyen, Dionysios Sema

Comments: 17 pages, 7 figures, and 10 tables

Subjects: Materials Science (cond-mat.mtrl-sci)

The development of interatomic potentials that can effectively capture a wide range of atomic environments is a complex challenge due to several reasons. Materials can exist in numerous structural forms (e.g., crystalline, amorphous, defects, interfaces) and phases (solid, liquid, gas, plasma). Each form may require different treatment in potential modeling to reflect the real physical behavior correctly. Atoms interact through various forces such as electrostatic, van der Waals, ionic bonding, covalent bonding, and metallic bonding, which manifest differently depending on the chemical elements and their electronic structures. Furthermore, the effective interaction among atoms can change with external conditions like temperature, pressure, and chemical environment. Consequently, creating an interatomic potential that performs well across diverse conditions is difficult since optimizing the potential for one set of conditions can lead to a trade-off in the accuracy of predicted properties associated with other conditions. In this paper, we present a method to construct accurate, efficient and transferable interatomic potentials by adapting to the local atomic environment of each atom within a system. The collection of atomic environments of interest is partitioned into several clusters of atomic environments. Each cluster represents a distinctive local environment and is used to define a corresponding local potential. We introduce a many-body many-potential expansion to smoothly blend these local potentials to ensure global continuity of the potential energy surface. This is achieved by computing the probability functions that determine the likelihood of an atom belonging to each cluster. We apply the environment-adaptive machine learning potentials to predict observable properties for Ta element and InP compound, and compare them with density functional theory calculations.

[15]  arXiv:2405.00346 [pdf, ps, other]

Title: Glass clarified as the self-organizing system

Authors: Elena A. Chechetkina

Comments: 11 pages, 11 figures, 4 tables

Subjects: Materials Science (cond-mat.mtrl-sci)

The synergetic approach proposed here is based on characteristic instability of chemical bonding in the form of the bond wave.The model explains characteristic hierarchical structure, including non-crystalline long-range order, the semi-deterministic behavior of properties, and a role of information fields for adaptation of glassy material to a current medium.

[16]  arXiv:2405.00379 [pdf, other]

Title: Planar Hall Effect in Quasi-Two-Dimensional Materials

Authors: Koushik Ghorai, Sunit Das, Harsh Varshney, Amit Agarwal

Comments: 5 pages, 3 figures, 1 table, Comments are welcome

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

The planar Hall effect in 3D systems is an effective probe for their Berry curvature, topology, and electronic properties. However, the Berry curvature-induced conventional planar Hall effect is forbidden in 2D systems as the out-of-plane Berry curvature cannot couple to the band velocity of the electrons moving in the 2D plane. Here, we demonstrate a unique 2D planar Hall effect (2DPHE) originating from the hidden planar components of the Berry curvature and orbital magnetic moment in quasi-2D materials. We identify all planar band geometric contributions to 2DPHE and classify their crystalline symmetry restrictions. Using gated bilayer graphene as an example, we show that in addition to capturing the hidden band geometric effects, 2DPHE is also sensitive to the Lifshitz transitions. Our work motivates further exploration of hidden planar band geometry-induced 2DPHE and related transport phenomena for innovative applications.

[17]  arXiv:2405.00381 [pdf, other]

Title: Tunable viscous layers in Corbino geometry using density junctions

Authors: Ramal Afrose, Aydin Cem Keser, Oleg Sushkov, Shaffique Adam

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

In sufficiently clean materials where electron-electron interactions are strong compared to momentum-relaxing scattering processes, electron transport resembles the flow of a viscous fluid. We study hydrodynamic electron transport across density interfaces (n-n junctions) in a 2DEG in the Corbino geometry. From numerical simulations in COMSOL using realistic parameters, we show that we can produce tunable viscous layers at the density interface by varying the density ratio of charge carriers. We quantitatively explain this observation with simple analytic expressions together with boundary conditions at the interface. We also show signatures of these viscous layers in the magnetoresistance. Breaking down viscous and ohmic contributions, we find that when outer radial region of the Corbino has higher charge density compared to the inner region, the viscous layers at the interface serve to suppress the magneto-resistance produced by momentum-relaxing scattering. Conversely, the magneto-resistance is enhanced when the inner region has higher density than the outer. Our results add to the repertoire of techniques for engineering viscous electron flows, which hold a promise for applications in future electronic devices.

[18]  arXiv:2405.00406 [pdf, other]

Title: Low-temperature thermal transport in moiré superlattices

Authors: Lukas P. A. Krisna, Takuto Kawakami, Mikito Koshino

Comments: 12 pages, 10 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

We calculate the thermal conductivity of various moir\'e bilayer systems using a continuum approach and the semiclassical transport theory. When the twist angle is close to 0, we observe a significant reduction of thermal conductivity in a particular low-temperature regime. This reduction is attributed to a moir\'e-induced reconstruction of acoustic phonon bands and associated decrease of the group velocity. Conversely, in the zero temperature limit, the thermal conductivity is enhanced by moir\'e effect, surpassing the original values in non-moir\'e counterparts. These changes result in a characteristic temperature dependence which deviates from the quadratic behavior in intrinsic two-dimensional systems.

[19]  arXiv:2405.00409 [pdf, other]

Title: Unconventional pairing in Ising superconductors: Application to monolayer NbSe$_2$

Authors: Subhojit Roy, Andreas Kreisel, Brian M. Andersen, Shantanu Mukherjee

Subjects: Superconductivity (cond-mat.supr-con)

The presence of a non-centrosymmetric crystal structure and in-plane mirror symmetry allows an Ising spin-orbit coupling to form in some two-dimensional materials. Examples include transition metal dichalcogenide superconductors like monolayer NbSe$_2$, MoS$_2$, TaS$_2$, and PbTe$_2$, where a nontrivial nature of the superconducting state is currently being explored. In this study, we develop a microscopic formalism for Ising superconductors that captures the superconducting instability arising from a momentum-dependent spin- and charge-fluctuation-mediated pairing interaction. We apply our pairing model to the electronic structure of monolayer NbSe$_2$, where first-principles calculations reveal the presence of strong paramagnetic fluctuations. Our calculations provide a quantitative measure of the mixing between the even- and odd-parity superconducting states and its variation with Coulomb interaction. Further, numerical analysis in the presence of an external Zeeman field reveals the role of Ising spin-orbit coupling and mixing of odd-parity superconducting state in influencing the low-temperature enhancement of the critical magnetic field.

[20]  arXiv:2405.00411 [pdf, other]

Title: Direct detection of down-converted photons spontaneously produced at a single Josephson junction

Authors: Dorian Fraudet, Izak Snyman, Denis M. Basko, Sébastien Léger, Théo Sépulcre, Arpit Ranadive, Gwenael Le Gal, Alba Torras-Coloma, Serge Florens, Nicolas Roch

Comments: 16 pages including supplementary material, 8 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

We study spontaneous photon decay into multiple photons triggered by strong non-linearities in a superconducting quantum simulator of the boundary sine-Gordon impurity model. Previously, spectroscopic signatures of photon-conversion were reported and evidenced as resonances in the many-body spectrum of these systems. Here, we report on the observation of multi-mode fluorescence of a small Josephson junction embedded in a high impedance superconducting transmission line. Measurement of the down-converted photons is achieved using state-of-the-art broadband parametric amplifiers. Photon triplet emission is explicitly demonstrated at a given frequency as the counterpart of inelastic photon decay at three-times the emission frequency. These results open exciting prospects for the burgeoning field of many-body quantum optics and offer a direct signature of the ultra-strong light-matter coupling.

[21]  arXiv:2405.00425 [pdf, other]

Title: Quantum Monte Carlo study of the phase diagram of the two-dimensional uniform electron liquid

Authors: Sam Azadi, N.D. Drummond, S.M. Vinko

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Plasma Physics (physics.plasm-ph); Quantum Physics (quant-ph)

We present a study of spin-unpolarized and spin-polarized two-dimensional uniform electron liquids using variational and diffusion quantum Monte Carlo (VMC and DMC) methods with Slater-Jastrow-backflow trial wave functions. Ground-state VMC and DMC energies are obtained in the density range $1 \leq r_\text{s} \leq 40$. Single-particle and many-body finite-size errors are corrected using canonical-ensemble twist-averaged boundary conditions and extrapolation of twist-averaged energies to the thermodynamic limit of infinite system size. System-size-dependent errors in Slater-Jastrow-backflow DMC energies caused by partially converged VMC energy minimization calculations are discussed. We find that, for $1 \leq r_\text{s} \leq 5$, optimizing the backflow function at each twist lowers the twist-averaged DMC energy at finite system size. However, nonsystematic system-size-dependent effects remain in the DMC energies, which can be partially removed by extrapolation from multiple finite system sizes to infinite system size. We attribute these nonsystematic effects to the close competition between fluid and defected crystal phases at different system sizes at low density. The DMC energies in the thermodynamic limit are used to parameterize a local spin density approximation correlation functional for inhomogeneous electron systems. Our zero-temperature phase diagram shows a single transition from a paramagnetic fluid to a hexagonal Wigner crystal at $r_\text{s}=35(1)$, with no region of stability for a ferromagnetic fluid.

[22]  arXiv:2405.00439 [pdf, ps, other]

Title: Fractional domain wall statistics in spin chains with anomalous symmetries

Authors: Jose Garre Rubio, Norbert Schuch

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Quantum Physics (quant-ph)

We study the statistics of domain wall excitations in quantum spin chains. We focus on systems with finite symmetry groups represented by matrix product unitaries (MPUs), i.e. finite depth quantum circuits. Such symmetries can be anomalous, in which case gapped phases which they support must break the symmetry. The lowest lying excitations of those systems are thus domain wall excitations. We investigate the behavior of these domain walls under exchange, and find that they can exhibit non-trivial exchange statistics. This statistics is completely determined by the anomaly of the symmetry, and we provide a direct relation between the known classification of MPU symmetry actions on ground states and the domain wall statistics. Already for the simplest case of a $\mathbb Z_2$ symmetry, we obtain that the presence of an anomalous MPU symmetry gives rise to domain wall excitations which behave neither as bosons nor as fermions, but rather exhibit fractional statistics. Finally, we show that the exchange statistics of domain walls is a physically accessible quantity, by devising explicit measurement operators through which it can be determined.

[23]  arXiv:2405.00443 [pdf, other]

Title: $1/f^α$ noise in the Robin Hood model

Authors: Abha Singh, Rahul Chhimpa, Avinash Chand Yadav

Comments: 12 pages, 8 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech)

We consider the Robin Hood dynamics, a one-dimensional extremal self-organized critical model that describes the evolution of low-temperature creep. One of the key quantities is the time evolution of the state variable (force noise). To understand the temporal correlations, we compute the power spectra of the local force fluctuations and apply finite-size scaling to get scaling functions and critical exponents. We find a signature of the $1/f^{\alpha}$ noise for the local force with a nontrivial value of the spectral exponent $0< \alpha < 2$. We also examine temporal fluctuations in the position of the extremal site and a local activity signal. We present results for different local interaction rules of the model.

[24]  arXiv:2405.00458 [pdf, other]

Title: Bulk-Boundary Correspondence in Ergodic and Nonergodic One-Dimensional Stochastic Processes

Authors: Taro Sawada, Kazuki Sone, Kazuki Yokomizo, Yuto Ashida, Takahiro Sagawa

Comments: 6+17 pages, 4+7 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Statistical Mechanics (cond-mat.stat-mech)

Bulk-boundary correspondence is a fundamental principle in topological physics. In recent years, there have been considerable efforts in extending the idea of geometry and topology to classical stochastic systems far from equilibrium. However, it has been unknown whether or not the bulk-boundary correspondence can be extended to the steady states of stochastic processes accompanied by additional constraints such as the conservation of probability. The present study reveals the general form of bulk-boundary correspondence in classical stochastic processes. Specifically, we prove a correspondence between the winding number and the number of localized steady states in both ergodic and nonergodic systems. Furthermore, we extend the argument of the bulk-boundary correspondence to a many-body stochastic model called the asymmetric simple exclusion process (ASEP). These results would provide a guiding principle for exploring topological origin of localization in various stochastic processes including biological systems.

[25]  arXiv:2405.00460 [pdf, other]

Title: Metallic local-moment magnetocalorics as a route to cryogenic refrigeration

Authors: Thomas Gruner, Jiasheng Chen, Dongjin Jang, Jacintha Banda, Christoph Geibel, Manuel Brando, F. Malte Grosche

Comments: 9 pages, 4 figures

Journal-ref: Communications Materials volume 5, Article number: 63 (2024)

Subjects: Strongly Correlated Electrons (cond-mat.str-el)

Commercial adiabatic demagnetisation refrigerators still employ the same hydrated salts that were first introduced over 85 years ago. The inherent limitations of these insulating magnetocalorics - poor thermal conductivity at sub-Kelvin temperatures, low entropy density, corrosiveness - can be overcome by a new generation of rare-earth based metallic magnetocalorics. Here, we present the metallic magnetocaloric YbNi1.6 Sn as an attractive alternative to conventional refrigerants. YbNi1.6Sn retains high entropy into the 100 mK regime and avoids the noble metal constituents of alternative refrigerants. Demagnetisation tests demonstrate that YbNi1.6Sn enables economical and durable alternatives to traditional cooling devices for temperatures reaching below 120 mK. We find that the magnetocaloric properties of this material are facilitated by unusually small Kondo and RKKY interactions, which position YbNi1.6Sn in the extreme local moment limit on the generalised Kondo lattice phase diagram.

[26]  arXiv:2405.00475 [pdf, other]

Title: To restart, or not to restart, that is the question

Authors: R. K. Singh

Comments: 5 pages, 3 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech)

The mean time taken by a Brownian particle to cover a distance $L$ is $L^2/2D$, with $D$ being its diffusion coefficient. We find that restarts increase this mean time. This is because restarts naturally introduce time overheads which need to be taken into account while addressing the escape properties. In addition, restarts impose a constraint on allowed overhead functions if they are to provide an advantage, that is, a reduced mean escape time. We explicitly study these constraints for Poisson and sharp restarts. Implementing an overhead function to control escape times means that the physical properties of the Brownian particle need to be appropriately modified. When restarts are non-instantaneous, an additional delay is introduced increasing the mean escape time further. Can restarts overcome the delays incurred due to finite return times? To restart, or not to restart, should be the question.

[27]  arXiv:2405.00477 [pdf, other]

Title: Beyond the random phase approximation for calculating Curie temperatures in ferromagnets: application to Fe, Ni, Co and monolayer CrI3

Authors: Varun Rajeev Pavizhakumari, Thorbjørn Skovhus, Thomas Olsen

Comments: 16 pages, 4 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

The magnetic properties of solids are typically analyzed in terms of Heisenberg models where the electronic structure is approximated by interacting localized spins. However, even in such models the evaluation of thermodynamic properties constitutes a major challenge and is usually handled by a mean field decoupling scheme. The random phase approximation (RPA) comprises a common approach and is often applied to evaluate critical temperatures although it is well known that the method is only accurate well below the critical temperature. In the present work we compare the performance of the RPA with a different decoupling scheme proposed by Callen as well as the mean field decoupling of interacting Holstein-Primakoff (HP) magnons. We consider three-dimensional (3D) as well as two-dimensional (2D) model systems where the Curie temperature is governed by anisotropy. In 3D, the Callen method is the most accurate in the classical limit, and we show that the Callen decoupling produces the best agreement with experiments for bcc Fe, fcc Ni and fcc Co with exchange interactions obtained from first principles. In contrast, for low spin systems where a quantum mechanical treatment in pertinent, the HP and RPA methods appear are superior to the Callen decoupling. In 2D systems with magnetic order driven by single-ion anisotropy, it is shown that HP fails rather dramatically and both RPA and Callen approaches severely overestimates Curie temperatures. The most accurate approach is then constructed by combining RPA with the Callen decoupling of single-ion anisotropy, which yields the correct lack of order for S=1/2. We exemplify this by the case of monolayer CrI3 using exchange constant extracted from experiments.

[28]  arXiv:2405.00487 [pdf, other]

Title: Recoverable strain from reverse plasticity

Authors: Henry A. Lockwood, Suzanne M. Fielding

Comments: submitted for publication, 11 pages, 6 figures

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci); Statistical Mechanics (cond-mat.stat-mech)

Recoverable strain is the strain recovered once a stress is removed from a body, in the direction opposite to that in which the stress had acted. To date, the phenomenon has been understood as being elastic in origin: polymer chains stretched in the direction of an imposed stress will recoil after the stress is removed, for example. Any unrecoverable strain is instead attributed to irreversible plastic deformations. Here we study theoretically recoverable and unrecoverable strain within the soft glassy rheology model, aimed at describing the rheology of elastoplastic yield stress fluids and amorphous soft solids. We consider a material subject to the switch-on of a shear stress that is held constant before later being set back to zero, after which the strain recovery is observed. After an initially fast recoil that is indeed elastic in nature, consistent with the usual intuition, we find that significant subsequent strain recovery then arises not via further recoil of elasticity but instead by `reverse plasticity', in a sense that we discuss carefully. Also unexpectedly, although in rare parameter regimes, this plastic part of the strain post switch-off does not always in fact recover in the negative direction, counter to that of the previously imposed stress, but can sometimes continue to accumulate in the forward direction. The recovery is then non-monotonic overall, reminiscent of recent observations of non-monotonic stress relaxation after straining, which have been attributed to complex material memory effects. We elucidate the mechanisms underlying these behaviours in terms of the evolution of the SGR model's population of elastoplastic elements, and suggest connections with the notion of `reversible plasticity', as discussed in the recent physics literature.

[29]  arXiv:2405.00508 [pdf, other]

Title: Hyperuniformity in phase ordering: the roles of activity, noise, and non-constant mobility

Authors: Filippo De Luca, Xiao Ma, Cesare Nardini, Michael E. Cates

Comments: 34 pages, 4 figures

Subjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech)

Hyperuniformity emerges generically in the coarsening regime of phase-separating fluids. Numerical studies of active and passive systems have shown that the structure factor $S(q)$ behaves as $q^\varsigma$ for $q\to 0$, with hyperuniformity exponent $\varsigma = 4$. For passive systems, this result was explained in 1991 by a qualitative scaling analysis of Tomita, exploiting isotropy at scales much larger than the coarsening length $\ell$. Here we reconsider and extend Tomita's argument to address cases of active phase separation and of non-constant mobility, again finding $\varsigma=4$. We further show that dynamical noise of variance $D$ creates a transient $\varsigma = 2$ regime for $\hat q\ll \hat{q}_\ast \sim \sqrt{D} t^{[1-(d+2)\nu]/2}$, crossing over to $\varsigma = 4$ at larger $\hat{q}$. Here, $\nu$ is the coarsening exponent, with $\ell\sim t^\nu$, and $\hat{q} \propto q \ell$ is the rescaled wavenumber. In diffusive coarsening, $\nu=1/3$, so the rescaled crossover wavevector $\hat{q}_\ast$ vanishes at large times when $d\geq 2$. The slowness of this decay suggests a natural explanation for experiments that observe a long-lived $\varsigma = 2$ scaling in phase-separating active fluids (where noise is typically large). Conversely, in $d=1$, we demonstrate that with noise the $\varsigma = 2$ regime survives as $t\to\infty$, with $\hat{q}_\ast\sim D^{5/6}$. (The structure factor is not then determined by the zero-temperature fixed point.) We confirm our analytical predictions by numerical simulations of active and passive continuum theories in the deterministic case and of Model B for the stochastic case. We also compare them with related findings for a system near an absorbing-state transition rather than undergoing phase separation. A central role is played throughout by the presence or absence of a conservation law for the centre of mass position of the order parameter field.

[30]  arXiv:2405.00517 [pdf, ps, other]

Title: Contrasting Irradiation Behavior of Dual Phases in Ti-6Al-4V Alloy at Low-Temperature Due to Omega-phase Precursors in Beta-phase Matrix

Authors: Taku Ishida, Sho Kano, Eiichi Wakai, Tamaki Shibayama, Shunsuke Makimura, Hiroaki Abe

Comments: 36 pages, 15 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Accelerator Physics (physics.acc-ph)

Aiming to simulate the radiation damage effect on a dual alpha+beta phase Ti-6Al-4V alloy utilized as high-intensity accelerator beam window material, a series of irradiation experiments were conducted with a 2.8 MeV-Fe^2+ ion beam in several dpa regions at room temperature. The nano-indentation hardness increased steeply at 1 dpa and unchanged up to 10 dpa, due to the saturation of defect clusters and tangled dislocations in the dominant alpha-phase matrix with a size of 2~3 nm and a density of about 1x10^23 m^-3. In contrast in the intergranular beta-phase, larger loops of 20~30 nm diameter were observed with much less density of about 5x10^20 m^-3. The diffraction pattern showed rectilinear diffuse streaks between the beta-phase reflections, corresponding to the omega-phase precursor, without dose dependency in its intensity. FFT/I-FFT analysis of the HREM revealed a sub-nanometer-sized lattice disorder with local fluctuations, not discrete but continuous, and homogeneously distributed within the matrix beta-phase stably against the irradiation. The significantly low dislocation density and the absence of phase transformation in the beta-phase matrix could be attributed either to the strong sink effect expected for this distinctive sub-nanometer-sized homogeneous lattice disorder or to the anomalous point defect recombination induced by the high mobility of vacancies, both of which are originated from the metastable omega-phase precursors specifically formed in the beta(BCC) phase of group-4 transition metals.

[31]  arXiv:2405.00534 [pdf, other]

Title: Non-Abelian line graph: A generalized approach to flat bands

Authors: Rui-Heng Liu, Xin Liu

Comments: 6 pages, 3 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Line graph (LG) lattices are well known to host flat bands (FBs) with isotropic hoppings in $s$-orbital models. Yet, higher-angular-momentum orbitals with spin-orbit coupling (SOC), which are more common in real materials, lack a general approach for their inclusion in LG to achieve FBs. Here, we introduce a non-Abelian LG theory to construct FBs in realistic systems, which incorporates internal degrees of freedom and goes beyond real-valued isotropic hoppings. The lattice edges and sites in the LG are modified to be associated with arbitrary Hermitian matrices, refereed to as multiple LG. A crucial step is to map the multiple LG Hamiltonian to a tight-binding (TB) model that respects the lattice symmetry through appropriate local non-Abelian transformations in the internal space. We find the general conditions to determine the local transformation. Based on this mechanism, we discuss the realization of $d$-orbital FBs in the Kagome lattice, which may serve as a minimal model for understanding the high-orbital FBs with SOC in Kagome materials. Our approach bridges the known FBs in pure lattice models and the realization in multi-orbital systems.

[32]  arXiv:2405.00538 [pdf, other]

Title: Probing valley phenomena with gate-defined valley splitters

Authors: Juan Daniel Torres Luna, Kostas Vilkelis, Antonio L. R. Manesco

Comments: 13 pages, 6 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Despite many reports of valley-related phenomena in graphene and its multilayers, current transport experiments cannot probe valley phenomena without the application of external fields. Here we propose a gate-defined valley splitter as a direct transport probe for valley phenomenon in graphene multilayers. First, we show how the device works, its magnetotransport response, and its robustness against fabrication errors. Secondly, we present two applications for valley splitters: (i) resonant tunneling of quantum dots probed by a valley splitter shows the valley polarization of dot levels; (ii) a combination of two valley splitters resolves the nature of order parameters in mesoscopic samples.

[33]  arXiv:2405.00550 [pdf, ps, other]

Title: Spin-spin correlators on the $β$/$β^{\star}$ boundaries in 2D Ising-like models: non-universality in the scaling region

Authors: Yizhuang Liu

Comments: 12 pages

Subjects: Statistical Mechanics (cond-mat.stat-mech); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph)

In this work, we investigate quantitative properties of correlation functions on the boundaries between two 2D Ising-like models with dual parameters $\beta$ and $\beta^{\star}$. Spin-spin correlators in such constructions without reflection symmetry with respect to transnational-invariant directions are usually represented as $2\times 2$ block Toeplitz determinants which are normally significantly harder than the scalar ($1\times 1$-blocked) versions. Nevertheless, we show that for the specific $\beta/\beta^{\star}$ boundaries considered in this work, the symbol matrices allow explicit commutative Wiener-Hopf factorizations. However, the Wiener-Hopf factors at different $z$ do not commute. We will show that due to this non-commutativity, "logarithmic divergences" and non-universal short distance contributions in the Wiener-Hopf factors fail to factorize out completely in the re-scaled correlators. This leads to non-universality of the leading large $r$ asymptotics at the order $\frac {e^{-r}}{r^{\frac{3}{2}}}$, even when the constant terms are re-scaled to be the same.

[34]  arXiv:2405.00590 [pdf, other]

Title: Nonlinear Poisson effect in affine semiflexible polymer networks

Authors: Jordan L. Shivers, Fred C. MacKintosh

Subjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph)

Stretching an elastic material along one axis typically induces contraction along the transverse axes, a phenomenon known as the Poisson effect. From these strains, one can compute the specific volume, which generally either increases or, in the incompressible limit, remains constant as the material is stretched. However, in networks of semiflexible or stiff polymers, which are typically highly compressible yet stiffen significantly when stretched, one instead sees a significant reduction in specific volume under finite strains. This volume reduction is accompanied by increasing alignment of filaments along the strain axis and a nonlinear elastic response, with stiffening of the apparent Young's modulus. For semiflexible networks, in which entropic bending elasticity governs the linear elastic regime, the nonlinear Poisson effect is caused by the nonlinear force-extension relationship of the constituent filaments, which produces a highly asymmetric response of the constituent polymers to stretching and compression. The details of this relationship depend on the geometric and elastic properties of the underlying filaments, which can vary greatly in experimental systems. Here, we provide a comprehensive characterization of the nonlinear Poisson effect in an affine network model and explore the influence of filament properties on essential features of the macroscopic response, including strain-driven alignment and volume reduction.

[35]  arXiv:2405.00609 [pdf, ps, other]

Title: Capillary-Assisted Printing of Droplets at a Solid-Like Liquid-Liquid Interface

Authors: Anshu Thapa, Robert Malinowski, Matthew O. Blunt, Giorgio Volpe, Joe Forth

Comments: 14 pages, 5 figures, 7 supplementary figures

Subjects: Soft Condensed Matter (cond-mat.soft)

Capillary forces guide the motion of biomolecular condensates, water-borne insects, and breakfast cereal. These surface-mediated interactions can be harnessed to build units into materials with exotic properties deriving from mesoscale structure. Droplets are promising building blocks for these materials, finding applications in tissue engineering, adaptive optics, and structural colour. However, the instability of water droplets at many liquid-liquid interfaces hampers the use of capillarity for the assembly of droplet-based materials. Here, we use nanoparticle surfactants to form solid-like oil-water interfaces at which aqueous droplets sit for extended periods. We find that microlitre-sized droplets at these interfaces attract each other over millimetric scales. We rationalize this interaction with a modified theory of capillarity. Applying printing methods allows us to finely control initial droplet positions, from which they self-assemble into cellular materials. Finally, by functionalising the interface with gold nanoparticles, we use plasmon-assisted optofluidics to manipulate these droplet-based materials with temperature gradients.

[36]  arXiv:2405.00628 [pdf, other]

Title: Metamagnetism and anomalous magnetotransport properties in rare-earth-based polar semimetals $R$AuGe ($R =$ Dy, Ho, and Gd)

Authors: Takashi Kurumaji, Masaki Gen, Shunsuke Kitou, Taka-hisa Arima

Comments: 11 pages, 9 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci)

We report the magnetic, magnetoelastic, and magnetotransport properties of single crystals of polar magnets $R$AuGe ($R=$ Dy, Ho, and Gd), grown by Au-Ge self-flux. Magnetization and magnetostriction measurements reveal multi-step metamagnetic transitions for the $c$-axis magnetic field ($H\parallel c$) for DyAuGe and HoAuGe, suggesting magnetic frustration in the triangular lattice of $R$ ions. The magnetic phase diagrams have clarified a close connection between the magnetoelastic property and the emergence of the intermediate metamagentic phase. The magnetic-field dependence of the resistivity and Hall resistivity reveal the semimetallic transport dominated by hole-type carriers, consistent with the behavior in a nonmagnetic analogue YAuGe. We also identify a signature of an anomalous Hall effect (AHE) proportional to the field-induced magnetization in $R=$ Dy, Ho, and Gd. GdAuGe shows magnetic and transport behavior as reported in a previous study using Bi-flux grown single crystals, while the self-flux grown crystal shows larger magnetoresistance ($\sim$ 345\%, at 1.8 K and 9 T) due to higher hole-type carrier mobility ($\sim$ 6400 cm$^2$/Vs). Using the two-band model analysis considering the mobility change during the magnetization process, we extract the anomalous Hall conductivity: $\sim 1200$ S/cm and $\sim 530$ S/cm for $R=$ Dy and Ho, respectively, at 1.8 K with 9 T for $H\parallel c$. The magnitude of conductivity suggests a contribution of intrinsic origin, possibly related to the Berry curvature in the electron bands induced by the time-reversal symmetry breaking and the polar lattice.

[37]  arXiv:2405.00639 [pdf, other]

Title: Vacancy-mediated transport and segregation tendencies of solutes in FCC nickel under diffusional creep: A density functional theory study

Authors: Shehab Shousha, Sourabh Bhagwan Kadambi, Benjamin Beeler, Boopathy Kombaiah

Subjects: Materials Science (cond-mat.mtrl-sci)

The Nabarro-Herring (N-H) diffusional creep theory postulates the vacancy-mediated transport of atoms under a stress gradient as the creep mechanism under low-stress and high-temperature conditions. In multicomponent alloys, we premise that this stress-assisted flow of vacancies to and from grain boundaries will produce elemental segregation. An observation of such segregation, validated with theoretical predictions, can provide the necessary experimental evidence for the occurrence of N-H creep. Theoretical calculations of the segregation tendencies via analyzing the dominant solute diffusion mechanisms and the difference in diffusivities of the elements are therefore essential. To this end, this study applies density functional theory calculations of migration barriers and solute-vacancy binding energies as input to the self-consistent mean field theory to assess the vacancy-mediated diffusion mechanisms, transport coefficients, and segregation tendencies of Co, Cr, Mo, Re, Ta, and W solutes in face-centered cubic Ni. We find Co, Re, and W to be slow diffusers at high temperatures and Cr, Mo, and Ta to be fast diffusers. Further analysis shows that the slow diffusers tend to always enrich at vacancy sinks over a wide range of temperatures. In contrast, the fast diffusers show a transition from depletion to enrichment as the temperature lowers. Furthermore, our analysis of the segregation tendencies under tensile hydrostatic strains shows that slow diffusers are largely unaffected by the strain and favor enrichment. On the other hand, the fast diffusers exhibit high sensitivity to strain and their segregation tendency can transition from depletion to enrichment at a given temperature. The transport coefficients calculated in this work are expected to serve as input to mesoscale microstructure models to provide a more rigorous assessment of solute segregation under N-H creep conditions.

[38]  arXiv:2405.00643 [pdf, other]

Title: Electronic and Optical Excitations in van der Waals Materials from a Non-Empirical Wannier-Localized Optimally-Tuned Screened Range-Separated Hybrid Functional

Authors: María Camarasa-Gómez, Stephen E. Gant, Guy Ohad, Jeffrey B. Neaton, Ashwin Ramasubramanian, Leeor Kronik

Comments: 11 pages + 4 figures; Supporting Information (15 pages + 2 figures)

Subjects: Materials Science (cond-mat.mtrl-sci)

Accurate prediction of electronic and optical excitations in van der Waals (vdW) materials is a long-standing challenge for density functional theory. The recently proposed Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functional has proven successful in non-empirical determination of electronic band gaps and optical absorption spectra for various covalent and ionic crystals. However, for vdW materials the tuning of the material- and structure-dependent functional parameters has, until now, only been attained semi-empirically. Here, we present a non-empirical WOT-SRSH approach applicable to vdW materials, with the optimal functional parameters transferable between monolayer and bulk. We apply this methodology to prototypical vdW materials: black phosphorus, molybdenum disulfide, and hexagonal boron nitride (in the latter case including zero-point renormalization). We show that the WOT-SRSH approach consistently achieves accuracy levels comparable to experiments and ab initio many-body perturbation theory (MBPT) calculations for band structures and optical absorption spectra, both on its own and as an optimal starting point for MBPT calculations.

[39]  arXiv:2405.00652 [pdf, other]

Title: Interplay between domain walls and magnetization curling induced by chemical modulations in cylindrical nanowires

Authors: L. Alvaro-Gómez, A. Masseboeuf, N. Mille, C. Fernández-Gonz ález, S. Ruiz-Gómez, J.C Toussaint, R. Belkhou, M. Foerster, E. Pereiro, L. Aballe, C. Thirion, D. Gusakova, O. Fruchart, L. Pérez

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Cylindrical magnetic nanowires have been proposed as a means of storing and processing information in a 3D medium, based on the motion of domain walls~(DWs). Introducing short chemical modulations in such wires would allow for reliable digital control of DWs. Here, we outline the intricate physics of the interaction of domain walls with modulations to control their motion, combining micromagnetic simulations and experimental evidence. This interaction combines a long-range moderate magnetostatic repulsion with a local energy well. The latter depends on the respective circulation sense of magnetization in the domain wall and modulation. We also show that a modulation has the ability to switch the internal circulation of a DW upon its propagation, thereby acting as a polarizing component and opening the possibility to exploit not only the position of walls, but also their internal structure.

[40]  arXiv:2405.00653 [pdf, other]

Title: Particle scale anisotropy controls bulk properties in sheared granular materials

Authors: Carmen L. Lee, Ephraim Bililign, Emilien Azéma, Karen E. Daniels

Comments: 5 pages, 3 figures

Subjects: Soft Condensed Matter (cond-mat.soft)

The bulk dynamics of dense granular materials arise through a combination of particle-scale and mesoscale effects. Theoretical and numerical studies have shown that collective effects are created by particle-scale anisotropic structures such as grain connectivity (fabric), force transmission, and frictional mobilization, all of which influence bulk properties like bulk friction and the stress tensor through the Stress-Force-Fabric (SFF) relationship. To date, establishing the relevance of these effects to laboratory systems has remained elusive due to the challenge of measuring both normal and frictional contact forces at the particle scale. In this study, we perform experiments on a sheared photoelastic granular system in an quasi-2D annular (Couette) cell. During these experiments, we measure particle locations, contacts, and normal and frictional forces vectors during loading. We reconstruct the angular distributions of the contact and force vectors, and extract the corresponding emergent anisotropies for each of these metrics. Finally, we show that the SFF relation quantitatively predicts the relationship between particle scale anisotropies, the stress tensor components, and the bulk friction coefficient, capturing even transient behaviors. As such, this method shows promise for application to other dense particulate systems where fabric anisotropy can provide a useful measure of bulk friction.

[41]  arXiv:2405.00654 [pdf, other]

Title: Large deviations of current for the symmetric simple exclusion process on a semi-infinite line and on an infinite line with slow bonds

Authors: Kapil Sharma, Soumyabrata Saha, Sandeep Jangid, Tridib Sadhu

Comments: 7 pages, 4 figures (Supplementary Materials: 8 pages, 2 figures)

Subjects: Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph)

Two of the most influential exact results for classical one-dimensional diffusive transport are the exact results of current statistics for the symmetric simple exclusion process in the stationary state on a finite line coupled with two unequal reservoirs at the boundary and in the non-stationary state on an infinite line. We present the corresponding result for the intermediate geometry of a semi-infinite line coupled with a single reservoir. These results are obtained using the fluctuating hydrodynamics framework of the macroscopic fluctuation theory and confirmed by rare event simulations using a cloning algorithm. Our exact result enables us to address the corresponding problem on an infinite line in the presence of a slow region and several related problems.

Cross-lists for Thu, 2 May 24

[42]  arXiv:2404.19670 (cross-list from physics.atom-ph) [pdf, other]

Title: Magnetic trapping of an ultracold $^{39}$K-$^{40}$K mixture with a versatile potassium laser system

Authors: Mateusz Bocheński, Jakub Dobosz, Mariusz Semczuk

Comments: 15 pages, 7 figures

Subjects: Atomic Physics (physics.atom-ph); Quantum Gases (cond-mat.quant-gas)

We present a dual isotope magneto-optical trap (MOT), simultaneous sub-Doppler laser cooling, and magnetic trapping of a spin-polarized $^{39}$K-$^{40}$K Bose-Fermi mixture realized in a single-chamber setup with an unenriched potassium dispenser as the source of atoms. We are able to magnetically confine more than $2.2\times10^5$ fermions ($F=9/2\,m_F=9/2$) and $1.4\times10^7$ bosons ($F=2\,m_F=2$) with a lifetime exceeding 1.2 s. For this work, we have developed a versatile laser tailored for sub-Doppler cooling of all naturally occurring potassium isotopes and their mixtures. This laser system incorporates innovative features, such as the capability to select an isotope by activating or deactivating specific acousto-optic modulators that control the light seeding tapered amplifiers. Switching between isotopes takes $\sim$1 $\mathrm{\mu}$s without any mechanical adjustment of the components. As a final step in characterizing the laser system, we demonstrate sub-Doppler cooling of $^{41}$K.

[43]  arXiv:2405.00041 (cross-list from physics.soc-ph) [pdf, other]

Title: A theory of best choice selection through objective arguments grounded in Linear Response Theory concepts

Authors: Marcel Ausloos, Giulia Rotundo, Roy Cerqueti

Comments: 25 pages, 2 figures, 5 tables, 72 references; accepted in a Special Issue of the journal Physics in honor of Serge Galam for his 70th birthday and 40 years of Sociophysics

Subjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech); Information Theory (cs.IT)

In this paper, we propose how to use objective arguments grounded in statistical mechanics concepts in order to obtain a single number, obtained after aggregation, which would allow to rank "agents", "opinions", ..., all defined in a very broad sense. We aim toward any process which should a priori demand or lead to some consensus in order to attain the presumably best choice among many possibilities. In order to precise the framework, we discuss previous attempts, recalling trivial "means of scores", - weighted or not, Condorcet paradox, TOPSIS, etc. We demonstrate through geometrical arguments on a toy example, with 4 criteria, that the pre-selected order of criteria in previous attempts makes a difference on the final result. However, it might be unjustified. Thus, we base our "best choice theory" on the linear response theory in statistical mechanics: we indicate that one should be calculating correlations functions between all possible choice evaluations, thereby avoiding an arbitrarily ordered set of criteria. We justify the point through an example with 6 possible criteria. Applications in many fields are suggested. Beside, two toy models serving as practical examples and illustrative arguments are given in an Appendix.

[44]  arXiv:2405.00215 (cross-list from quant-ph) [pdf, other]

Title: Quantum thermodynamics of the Caldeira-Leggett model with non-equilibrium Gaussian reservoirs

Authors: Vasco Cavina, Massimiliano Esposito

Comments: 38 pages, 6 figures

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech)

We introduce a non-equilibrium version of the Caldeira-Leggett model in which a quantum particle is strongly coupled to a set of engineered reservoirs. The reservoirs are composed by collections of squeezed and displaced thermal modes, in contrast to the standard case in which the modes are assumed to be at equilibrium. The model proves to be very versatile. Strongly displaced/squeezed reservoirs can be used to generate an effective time dependence in the system Hamiltonian and can be identified as sources of pure work. In the case of squeezing, the time dependence is stochastic and breaks the fluctuation-dissipation relation, this can be reconciled with the second law of thermodynamics by correctly accounting for the energy used to generate the initial non-equilibrium conditions. To go beyond the average description and compute the full heat statistics, we treat squeezing and displacement as generalized Hamiltonians on a modified Keldysh contour. As an application of this technique, we show the quantum-classical correspondence between the heat statistics in the non-equilibrium Caldeira-Leggett model and the statistics of a classical Langevin particle under the action of squeezed and displaced colored noises. Finally, we discuss thermodynamic symmetries of the heat generating function, proving a fluctuation theorem for the energy balance and showing that the conservation of energy at the trajectory level emerges in the classical limit.

[45]  arXiv:2405.00275 (cross-list from astro-ph.GA) [pdf, ps, other]

Title: Near Infrared Diffuse Interstellar Bands Characterized by Fullerene and Graphene Molecules

Authors: Norio Ota

Comments: 14 pages, 11 figures, 3 tables, 5 appendixes

Subjects: Astrophysics of Galaxies (astro-ph.GA); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Astronomical near-infrared Diffuse-Interstellar-Bands (DIBs) were characterized by pure carbon Fullerene and Graphene molecules comparing with laboratory experiment and with Time-Dependent Density-Functional-Theory (TD-DFT) analysis. It is well known that two large DIBs of Fullerene cation (C60)+ at 9577A and 9632A coincide well with laboratory experiments. Those are thought to be split bands by the Jahn-Teller molecular deformation. In our TD-DFT calculation, those are reproduced by degenerated bands at 9549A and 9552A before deformation. Cation enriching experiment by Strelnikov et al. suggested longer wavelength two bands of DIB10542 and DIB10610 (observed by Hamano et al.), which may split from calculated 10410A and 10411A. Also, we noticed shorter wavelength experimental band around 8550A, which may relate to calculated 8677A and 8686A. We challenged such analysis on Graphene molecules as like (C54) (C53) (C52) and (C51), which are carbon hexagon and pentagon combined molecules. Calculation could reproduce many near-infrared bands. Calculated bands of (C54) suggest that one DIB among (DIB9577, DIB9632, or DIB9673) may correspond to one of (DIB10361, DIB10394, or DIB10439). Calculated bands of (C51) suggest that one of (DIB9686, DIB9987, or DIB10006) may relate to one of (DIB10262 or DIB10288). Combining astronomical observation, laboratory experiment, and quantum chemical analysis, we could suggest carrier candidates of DIBs.

[46]  arXiv:2405.00279 (cross-list from physics.chem-ph) [pdf, other]

Title: Beyond a Richardson-Gaudin mean-field: Slater-Condon rules and perturbation theory

Authors: Paul A. Johnson

Subjects: Chemical Physics (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el)

Richardson-Gaudin states provide a basis of the Hilbert space for strongly correlated electrons. In this study, optimal expressions for the transition density matrix elements between Richardson-Gaudin states are obtained with a cost comparable with the corresponding reduced density matrix elements. Analogues of the Slater-Condon rules are identified based on the number of near-zero singular values of the RG state overlap matrix. Finally, a perturbative approach is shown to be close in quality to a configuration interaction of Richardson-Gaudin states while being feasible to compute.

[47]  arXiv:2405.00328 (cross-list from quant-ph) [pdf, other]

Title: Discrete Time Crystal Phase as a Resource for Quantum Enhanced Sensing

Authors: Rozhin Yousefjani, Krzysztof Sacha, Abolfazl Bayat

Comments: Comments are welcome!

Subjects: Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el)

Discrete time crystals are a special phase of matter in which time translational symmetry is broken through a periodic driving pulse. Here, we first propose and characterize an effective mechanism to generate a stable discrete time crystal phase in a disorder-free many-body system with indefinite persistent oscillations even in finite-size systems. Then we explore the sensing capability of this system to measure the spin exchange coupling. The results show strong super-Heisenberg precision, in terms of system size, throughout the time crystal phase. As the spin exchange coupling varies, the system goes through a sharp phase transition and enters a non-time crystal phase in which the performance of the probe considerably decreases. We characterize this phase transition as a second-order type and determine its critical properties through a comprehensive finite-size scaling analysis. The performance of our probe is independent of the initial states and may even benefit from imperfections in the driving pulse.

[48]  arXiv:2405.00360 (cross-list from hep-th) [pdf, other]

Title: Heat capacity and quantum compressibility of dynamical spacetimes with thermal particle creation

Authors: Jen-Tsung Hsiang, Yu-Cun Xie, Bei-Lok Hu

Comments: 32 pages, 7 figures

Subjects: High Energy Physics - Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc)

This work continues the investigation in two recent papers on the quantum thermodynamics of spacetimes, 1) placing what was studied in [1] for thermal quantum fields in the context of early universe cosmology, and 2) extending the considerations of vacuum compressibility of dynamical spaces treated in [2] to dynamical spacetimes with thermal quantum fields. We begin with a warning that thermal equilibrium condition is not guaranteed to exist or maintained in a dynamical setting and thus finite temperature quantum field theory in cosmological spacetimes needs more careful considerations than what is often described in textbooks. A full description requires nonequilibrium quantum field theory in dynamical spacetimes using `in-in' techniques. A more manageable subclass of dynamics is where thermal equilibrium conditions are established at both the beginning and the end of evolution are both well defined. Here we shall assume an in-vacuum state. It has been shown that if the intervening dynamics has an initial period of exponential expansion, such as in inflationary cosmology, particles created from the parametric amplification of the vacuum fluctuations in the initial vacuum will have a thermal spectrum measured at the out-state. Under these conditions finite temperature field theory can be applied to calculate the quantum thermodynamic quantities. Here we consider a massive conformal scalar field in a closed four-dimensional Friedmann-Lemaitre-Robertson-Walker universe based on the simple analytically solvable Bernard-Duncan model. We calculate the energy density of particles created from an in-vacuum and derive the partition function. From the free energy we then derive the heat capacity and the quantum compressibility of the spacetimes with thermal particle creation. We end with some discussions and suggestions for further work in this program of studies.

[49]  arXiv:2405.00416 (cross-list from quant-ph) [pdf, other]

Title: Entanglement and fidelity across quantum phase transitions in locally perturbed topological codes with open boundaries

Authors: Harikrishnan K J, Amit Kumar Pal

Comments: 14 pages, 7 figures, 1 table

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el)

We investigate the topological-to-non-topological quantum phase transitions (QPTs) occurring in the Kitaev code under local perturbations in the form of local magnetic field and spin-spin interactions of the Ising-type using fidelity susceptibility (FS) and entanglement as the probes. We assume the code to be embedded on the surface of a wide cylinder of height $M$ and circumference $D$ with $M\ll D$. We demonstrate a power-law divergence of FS across the QPT, and determine the quantum critical points (QCPs) via a finite-size scaling analysis. We verify these results by mapping the perturbed Kitaev code to the 2D Ising model with nearest- and next-nearest-neighbor interactions, and computing the single-site magnetization as order parameter using quantum Monte-Carlo technique. We also point out an odd-even dichotomy in the occurrence of the QPT in the Kitaev ladder with respect to the odd and even values of $D$, when the system is perturbed with only Ising interaction. Our results also indicate a higher robustness of the topological phase of the Kitaev code against local perturbations if the boundary is made open along one direction. We further consider a local entanglement witness operator designed specifically to capture a lower bound to the localizable entanglement on the vertical non-trivial loop of the code. We show that the first derivative of the expectation value of the witness operator exhibits a logarithmic divergence across the QPT, and perform the finite-size scaling analysis. We demonstrate similar behaviour of the expectation value of the appropriately constructed witness operator also in the case of locally perturbed color code with open boundaries.

[50]  arXiv:2405.00484 (cross-list from physics.optics) [pdf, ps, other]

Title: Spin Hamiltonians in the Modulated Momenta of Light

Authors: Juan Feng, Zengya Li, Luqi Yuan, Erez Hasman, Bo Wang, Xianfeng Chen

Comments: 18 pages, 5 figures

Subjects: Optics (physics.optics); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)

Photonic solvers that are able to find the ground states of different spin Hamiltonians can be used to study many interactive physical systems and combinatorial optimization problems. Here, we establish a real-and-momentum space correspondence of spin Hamiltonians by spatial light transport. The real-space spin interaction is determined by modulating the momentum-space flow of light. This principle is formulated as a generalized Plancherel theorem, allowing us to implement a simple optical simulator that can find the ground states for any displacement-dependent spin interactions. Particularly, we use this principle to reveal the exotic magnetic phase diagram from a J1-J2-J3 model, and we also observe the vortex-mediated Berezinskii-Kosterlitz-Thouless dynamics from the XY model. These experiments exhibit high calculation precision by subtly controlling spin interactions from the momentum space of light, offering a promising scheme to explore novel physical effects.

[51]  arXiv:2405.00547 (cross-list from physics.bio-ph) [pdf, other]

Title: Transport of topological defects in a biphasic mixture of active and passive nematic fluids

Authors: KVS Chaithanya, Aleksandra Ardaševa, Oliver J. Meacock, William M. Durham, Sumesh P. Thampi, Amin Doostmohammadi

Subjects: Biological Physics (physics.bio-ph); Soft Condensed Matter (cond-mat.soft)

Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate $+1/2$ defects and expel $-1/2$ defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As $+1/2$ and $-1/2$ defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact.

[52]  arXiv:2405.00592 (cross-list from stat.ML) [pdf, other]

Title: Scaling and renormalization in high-dimensional regression

Authors: Alexander B. Atanasov, Jacob A. Zavatone-Veth, Cengiz Pehlevan

Comments: 64 pages, 16 figures

Subjects: Machine Learning (stat.ML); Disordered Systems and Neural Networks (cond-mat.dis-nn); Machine Learning (cs.LG)

This paper presents a succinct derivation of the training and generalization performance of a variety of high-dimensional ridge regression models using the basic tools of random matrix theory and free probability. We provide an introduction and review of recent results on these topics, aimed at readers with backgrounds in physics and deep learning. Analytic formulas for the training and generalization errors are obtained in a few lines of algebra directly from the properties of the $S$-transform of free probability. This allows for a straightforward identification of the sources of power-law scaling in model performance. We compute the generalization error of a broad class of random feature models. We find that in all models, the $S$-transform corresponds to the train-test generalization gap, and yields an analogue of the generalized-cross-validation estimator. Using these techniques, we derive fine-grained bias-variance decompositions for a very general class of random feature models with structured covariates. These novel results allow us to discover a scaling regime for random feature models where the variance due to the features limits performance in the overparameterized setting. We also demonstrate how anisotropic weight structure in random feature models can limit performance and lead to nontrivial exponents for finite-width corrections in the overparameterized setting. Our results extend and provide a unifying perspective on earlier models of neural scaling laws.

[53]  arXiv:2405.00597 (cross-list from quant-ph) [pdf, other]

Title: Non-abelian symmetry-resolved entanglement entropy

Authors: Eugenio Bianchi, Pietro Dona, Rishabh Kumar

Comments: 50 pages, 5 figures

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We introduce a mathematical framework for symmetry-resolved entanglement entropy with a non-abelian symmetry group. To obtain a reduced density matrix that is block-diagonal in the non-abelian charges, we define subsystems operationally in terms of subalgebras of invariant observables. We derive exact formulas for the average and the variance of the typical entanglement entropy for the ensemble of random pure states with fixed non-abelian charges. We focus on compact, semisimple Lie groups. We show that, compared to the abelian case, new phenomena arise from the interplay of locality and non-abelian symmetry, such as the asymmetry of the entanglement entropy under subsystem exchange, which we show in detail by computing the Page curve of a many-body system with $SU(2)$ symmetry.

[54]  arXiv:2405.00642 (cross-list from stat.ML) [pdf, other]

Title: From Empirical Observations to Universality: Dynamics of Deep Learning with Inputs Built on Gaussian mixture

Authors: Jaeyong Bae, Hawoong Jeong

Comments: 19 pages, 9 figures

Subjects: Machine Learning (stat.ML); Disordered Systems and Neural Networks (cond-mat.dis-nn); Statistical Mechanics (cond-mat.stat-mech); Machine Learning (cs.LG)

This study broadens the scope of theoretical frameworks in deep learning by delving into the dynamics of neural networks with inputs that demonstrate the structural characteristics to Gaussian Mixture (GM). We analyzed how the dynamics of neural networks under GM-structured inputs diverge from the predictions of conventional theories based on simple Gaussian structures. A revelation of our work is the observed convergence of neural network dynamics towards conventional theory even with standardized GM inputs, highlighting an unexpected universality. We found that standardization, especially in conjunction with certain nonlinear functions, plays a critical role in this phenomena. Consequently, despite the complex and varied nature of GM distributions, we demonstrate that neural networks exhibit asymptotic behaviors in line with predictions under simple Gaussian frameworks.

[55]  arXiv:2405.00663 (cross-list from quant-ph) [pdf, other]

Title: Quantum cryptographic protocols with dual messaging system via 2D alternate quantum walks and genuine single particle entangled states

Authors: Dinesh Kumar Panda, Colin Benjamin

Comments: 11 pages (including supplementary material), 2 figures and 1 table

Subjects: Quantum Physics (quant-ph); Disordered Systems and Neural Networks (cond-mat.dis-nn); Cryptography and Security (cs.CR); Quantum Algebra (math.QA); Optics (physics.optics)

Single-particle entangled states (SPES) can offer a more secure way of encoding and processing quantum information than their multi-particle counterparts. The SPES generated via a 2D alternate quantum-walk setup from initially separable states can be either 3-way or 2-way entangled. This letter shows that the generated genuine three-way and nonlocal two-way SPES can be used as cryptographic keys to securely encode two distinct messages simultaneously. We detail the message encryption-decryption steps and show the resilience of the 3-way and 2-way SPES-based cryptographic protocols against eavesdropper attacks like intercept-and-resend and man-in-the-middle. We also detail how these protocols can be experimentally realized using single photons, with the three degrees of freedom being OAM, path, and polarization. These have unparalleled security for quantum communication tasks. The ability to simultaneously encode two distinct messages using the generated SPES showcases the versatility and efficiency of the proposed cryptographic protocol. This capability could significantly improve the throughput of quantum communication systems.

Replacements for Thu, 2 May 24

[56]  arXiv:2206.03349 (replaced) [pdf, other]

Title: Semiclassical quantization conditions in strained moiré lattices

Authors: Simon Becker, Jens Wittsten

Comments: 54 pages, 7 figures. Updated introduction and acknowledgments. Fixed typos, and improved and clarified the presentation

Subjects: Analysis of PDEs (math.AP); Strongly Correlated Electrons (cond-mat.str-el); Mathematical Physics (math-ph); Spectral Theory (math.SP); Quantum Physics (quant-ph)

[57]  arXiv:2210.06685 (replaced) [pdf, ps, other]

Title: A robust and tunable Luttinger liquid in correlated edge of transition-metal second-order topological insulator Ta$_2$Pd$_3$Te$_5$

Authors: Anqi Wang, Yupeng Li, Guang Yang, Dayu Yan, Yuan Huang, Zhaopeng Guo, Jiacheng Gao, Jierui Huang, Qiaochu Zeng, Degui Qian, Hao Wang, Xingchen Guo, Fanqi Meng, Qinghua Zhang, Lin Gu, Xingjiang Zhou, Guangtong Liu, Fanming Qu, Tian Qian, Youguo Shi, Zhijun Wang, Li Lu, Jie Shen

Comments: 41 pages, 6 Main Figures + 14 Supplementary Figure

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

[58]  arXiv:2212.05278 (replaced) [pdf, other]

Title: Ring-Exchange Interaction Effects on Magnons in Dirac Magnet CoTiO$_3$

Authors: Yufei Li, Thuc T. Mai, M. Karaki, E.V. Jasper, K.F. Garrity, C. Lyon, D. Shaw, T. DeLazzer, A.J. Biacchi, R.L. Dally, D.M. Heligman, J. Gdanski, T. Adel, M.F. Muñoz, A. Giovannone, A. Pawbake, C. Faugueras, J.R. Simpson, K. Ross, N. Trivedi, Y.M. Lu, A.R. Hight Walker, R. Valdés Aguilar

Comments: 7 pages, 4 figures in main text, 27 pages and 11 figures in supplement. Accepted in PRB

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Other Condensed Matter (cond-mat.other)

[59]  arXiv:2212.11743 (replaced) [pdf, other]

Title: Amoeba Formulation of Non-Bloch Band Theory in Arbitrary Dimensions

Authors: Hong-Yi Wang, Fei Song, Zhong Wang

Comments: 21 pages, 11 figures, 1 table

Journal-ref: Physical Review X 14, 021011 (2024)

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Gases (cond-mat.quant-gas); Mathematical Physics (math-ph); Optics (physics.optics); Quantum Physics (quant-ph)

[60]  arXiv:2305.07679 (replaced) [pdf, other]

Title: Version 2.0.0 -- SPARC: Simulation Package for Ab-initio Real-space Calculations

Authors: Boqin Zhang, Xin Jing, Qimen Xu, Shashikant Kumar, Abhiraj Sharma, Lucas Erlandson, Sushree Jagriti Sahoo, Edmond Chow, Andrew J. Medford, John E. Pask, Phanish Suryanarayana

Comments: 13 pages, 2 figures

Subjects: Computational Physics (physics.comp-ph); Materials Science (cond-mat.mtrl-sci)

[61]  arXiv:2305.07694 (replaced) [pdf, other]

Title: Quasiuniversality from all-in-all-out Weyl quantum criticality in pyrochlore iridates

Authors: David Jonas Moser, Lukas Janssen

Comments: 6+7 pages, 4+5 figures, 0+2 tables; v2: published version

Journal-ref: Phys. Rev. B 109, L081111 (2024)

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th)

[62]  arXiv:2305.14983 (replaced) [pdf, other]

Title: Local gate control of Mott metal-insulator transition in a 2D metal-organic framework

Authors: Benjamin Lowe, Bernard Field, Jack Hellerstedt, Julian Ceddia, Henry L. Nourse, Ben J. Powell, Nikhil V. Medhekar, Agustin Schiffrin

Comments: 34 pages, 4 figures + SI 53 pages, 33 figures

Journal-ref: Nat Commun 15, 3559 (2024)

Subjects: Strongly Correlated Electrons (cond-mat.str-el)

[63]  arXiv:2305.16235 (replaced) [pdf, other]

Title: Stochastic thermodynamics of a probe in a fluctuating correlated field

Authors: Davide Venturelli, Sarah A. M. Loos, Benjamin Walter, Édgar Roldán, Andrea Gambassi

Comments: 7 pages, 3 figures (main) + 21 pages, 1 figure (SM)

Journal-ref: EPL, 146 (2024) 27001

Subjects: Statistical Mechanics (cond-mat.stat-mech); Soft Condensed Matter (cond-mat.soft)

[64]  arXiv:2306.15264 (replaced) [pdf, other]

Title: Qubit dephasing by spectrally diffusing quantum two-level systems

Authors: Shlomi Matityahu, Alexander Shnirman, Moshe Schechter

Comments: 16 pages, 2 figures

Journal-ref: Phys. Rev. Applied 21, 044055 (2024)

Subjects: Quantum Physics (quant-ph); Disordered Systems and Neural Networks (cond-mat.dis-nn)

[65]  arXiv:2307.00489 (replaced) [pdf, other]

Title: Theoretical Limits of Energy Extraction in Active Fluids

Authors: Shahriar Shadkhoo, Matt Thomson

Comments: 8+7 pages, 8 figures

Subjects: Soft Condensed Matter (cond-mat.soft); Other Condensed Matter (cond-mat.other); Statistical Mechanics (cond-mat.stat-mech); Fluid Dynamics (physics.flu-dyn)

[66]  arXiv:2307.14914 (replaced) [pdf, other]

Title: Reduced stress propagation leads to increased mechanical failure resistance in auxetic materials

Authors: Suzanne M. Fielding

Comments: 7 pages, 5 figures; accepted for publication, Proceedings of the National Academy of Sciences of the United States of America

Subjects: Statistical Mechanics (cond-mat.stat-mech); Materials Science (cond-mat.mtrl-sci); Soft Condensed Matter (cond-mat.soft)

[67]  arXiv:2308.05806 (replaced) [pdf, other]

Title: Gain-compensated metal cavity modes and a million-fold improvement of Purcell factors

Authors: Becca VanDrunen, Juanjuan Ren, Sebastian Franke, Stephen Hughes

Journal-ref: Optica Quantum 2, 85-90 (2024)

Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

[68]  arXiv:2308.13096 (replaced) [pdf, other]

Title: Electronic Structure Prediction of Multi-million Atom Systems Through Uncertainty Quantification Enabled Transfer Learning

Authors: Shashank Pathrudkar, Ponkrshnan Thiagarajan, Shivang Agarwal, Amartya S. Banerjee, Susanta Ghosh

Subjects: Materials Science (cond-mat.mtrl-sci); Disordered Systems and Neural Networks (cond-mat.dis-nn); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)

[69]  arXiv:2310.02580 (replaced) [pdf, ps, other]

Title: Self-consistent many-body metrology

Authors: Jae-Gyun Baak, Uwe R. Fischer

Comments: 6+7 pages, 4+4 figures; version as accepted by PRL

Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas)

[70]  arXiv:2310.06924 (replaced) [pdf, other]

Title: In-plane magnetic field driven conductance modulations in topological insulator kinks

Authors: Gerrit Behner, Kristof Moors, Yong Zhang, Michael Schleenvoigt, Alina Rupp, Erik Zimmermann, Abdur Rehman Jalil, Peter Schüffelgen, Hans Lüth, Detlev Grützmacher, Thomas Schäpers

Comments: Main Text (7 pages, 4 figures) and Supplemental Material (3 pages, 3 figures)

Journal-ref: Phys. Rev. B 109, 155429 (2024)

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

[71]  arXiv:2310.16811 (replaced) [pdf, other]

Title: Effect of initial conditions on current fluctuations in non-interacting active particles

Authors: Stephy Jose, Alberto Rosso, Kabir Ramola

Comments: 28 pages, 4 figures, 1 table

Subjects: Statistical Mechanics (cond-mat.stat-mech)

[72]  arXiv:2310.18352 (replaced) [pdf, other]

Title: Theory of Rayleigh-Brillouin optical activity light scattering applicable to chiral liquids

Authors: Robert P. Cameron, Emmanouil I. Alexakis, Aidan S. Arnold, Duncan McArthur

Subjects: Optics (physics.optics); Soft Condensed Matter (cond-mat.soft)

[73]  arXiv:2310.20385 (replaced) [pdf, other]

Title: Free energy and metastable states in the square-lattice $J_1$-$J_2$ Ising model

Authors: V. A. Abalmasov

Comments: 22 pages, 16 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Statistical Mechanics (cond-mat.stat-mech); Superconductivity (cond-mat.supr-con)

[74]  arXiv:2311.03012 (replaced) [pdf, other]

Title: The role of viscosity on drop impact forces

Authors: Vatsal Sanjay, Bin Zhang, Cunjing Lv, Detlef Lohse

Comments: version after first round of the review

Subjects: Fluid Dynamics (physics.flu-dyn); Soft Condensed Matter (cond-mat.soft)

[75]  arXiv:2311.05413 (replaced) [pdf, other]

Title: Strain fluctuations unlock ferroelectricity in wurtzites

Authors: Steven M. Baksa (1), Simon Gelin (1), Seda Oturak (1), Robert Jackson Spurling (1), Alireza Sepehrinezhad (2), Leonard Jacques (1), Susan E. Trolier-McKinstry (1), Adri C. T. van Duin (3), Jon-Paul Maria (1), Andrew M. Rappe (4), Ismaila Dabo (1) ((1) Department of Materials Science and Engineering, Pennsylvania State University, (2) Department of Engineering Science and Mechanics, Pennsylvania State University, (3) Department of Mechanical Engineering, Pennsylvania State University, (4) Department of Chemistry, University of Pennsylvania)

Comments: 11 pages, 5 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

[76]  arXiv:2311.07457 (replaced) [pdf, other]

Title: Scalar susceptibility of a diluted classical XY model

Authors: Reece Beattie-Hauser, Thomas Vojta

Comments: 8 pages, 8 figures embedded, final version as published

Journal-ref: Phys. Rev. B 109, 184202 (2024)

Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el)

[77]  arXiv:2311.09334 (replaced) [pdf, other]

Title: Lattice Hamiltonian for Adjoint QCD$_2$

Authors: Ross Dempsey, Igor R. Klebanov, Silviu S. Pufu, Benjamin T. Søgaard

Comments: 47 pages, 5 figures

Subjects: High Energy Physics - Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Lattice (hep-lat)

[78]  arXiv:2312.11798 (replaced) [pdf, other]

Title: Fracture process of composite material in a spring network model

Authors: Haruka Noguchi, Satoshi Yukawa

Comments: 6 pages, 9 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech)

[79]  arXiv:2401.04529 (replaced) [pdf, ps, other]

Title: Comment on Infrared dielectric function of Ga(As,P) semiconductor alloys near the reststrahlen bands (Applied Physics Letters 123, 172102, 2023)

Authors: A. Elmahjoubi, T. Alhaddad, A.V. Postnikov, O. Pages

Comments: 23 pages, 6 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

[80]  arXiv:2401.10916 (replaced) [pdf, ps, other]

Title: Thermodynamics and Kinetics of Silicate Glasses submitted to Binary Ion Exchange: Equilibrium Conditions and Interdiffusion Kinetics

Authors: Guglielmo Macrelli

Comments: 32 pages, 10 figures, 2 tables, 69 equations, 48 References

Subjects: Materials Science (cond-mat.mtrl-sci); Statistical Mechanics (cond-mat.stat-mech)

[81]  arXiv:2401.13767 (replaced) [pdf, other]

Title: The emergence of antiferromagnetic correlations and Kondo-like features in a two-band model for infinite-layer nickelates

Authors: Fangze Liu, Cheng Peng, Edwin W. Huang, Brian Moritz, Chunjing Jia, Thomas P. Devereaux

Subjects: Strongly Correlated Electrons (cond-mat.str-el)

[82]  arXiv:2401.14396 (replaced) [pdf, other]

Title: Entanglement entropy and deconfined criticality: emergent SO(5) symmetry and proper lattice bipartition

Authors: Jonathan D'Emidio, Anders W. Sandvik

Comments: 5 pages, 3 figures + supplemental material

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Lattice (hep-lat)

[83]  arXiv:2401.16544 (replaced) [pdf, other]

Title: Stochastic Distinguishability of Markovian Trajectories

Authors: Asawari Pagare, Zhongmin Zhang, Jiming Zheng, Zhiyue Lu

Subjects: Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph); Quantitative Methods (q-bio.QM)

[84]  arXiv:2402.06256 (replaced) [pdf, other]

Title: Active Sparse Bayesian Committee Machine Potential for Isothermal-Isobaric Molecular Dynamics Simulations

Authors: Soohaeng Yoo Willow, Dong Geon Kim, R. Sundheep, Amir Hajibabaej, Kwang S. Kim, Chang Woo Myung

Comments: 10 pages, 4 figures, 1 table, submitted to Journal

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci)

[85]  arXiv:2402.10932 (replaced) [pdf, ps, other]

Title: Roadmap on Data-Centric Materials Science

Authors: Stefan Bauer, Peter Benner, Tristan Bereau, Volker Blum, Mario Boley, Christian Carbogno, C. Richard A. Catlow, Gerhard Dehm, Sebastian Eibl, Ralph Ernstorfer, Ádám Fekete, Lucas Foppa, Peter Fratzl, Christoph Freysoldt, Baptiste Gault, Luca M. Ghiringhelli, Sajal K. Giri, Anton Gladyshev, Pawan Goyal, Jason Hattrick-Simpers, Lara Kabalan, Petr Karpov, Mohammad S. Khorrami, Christoph Koch, Sebastian Kokott, Thomas Kosch, Igor Kowalec, Kurt Kremer, Andreas Leitherer, Yue Li, Christian H. Liebscher, Andrew J. Logsdail, Zhongwei Lu, Felix Luong, Andreas Marek, Florian Merz, Jaber R. Mianroodi, Jörg Neugebauer, Zongrui Pei, Thomas A. R. Purcell, Dierk Raabe, Markus Rampp, Mariana Rossi, Jan-Michael Rost, James Saal, Ulf Saalmann, Kasturi Narasimha Sasidhar, Alaukik Saxena, Luigi Sbailò, et al. (12 additional authors not shown)

Comments: Review, outlook, roadmap, perspective

Subjects: Materials Science (cond-mat.mtrl-sci); Data Analysis, Statistics and Probability (physics.data-an)

[86]  arXiv:2403.01719 (replaced) [src]

Title: Vortex formation and exotic superconducting states in field-cooled Sn-Pb solders

Authors: Takumi Murakami, Md. Riad Kasem, Hiroto Arima, Yuto Watanabe, Aichi Yamashita, Yoshikazu Mizuguchi

Comments: We found a problem on the analysis of specific heat data because of possible self-heating of the measured solders when flux reduction. We will resubmit the data after careful analyses

Subjects: Superconductivity (cond-mat.supr-con); Materials Science (cond-mat.mtrl-sci)

[87]  arXiv:2403.12275 (replaced) [pdf, other]

Title: Fast and accurate nonadiabatic molecular dynamics enabled through variational interpolation of correlated electron wavefunctions

Authors: Kemal Atalar, Yannic Rath, Rachel Crespo-Otero, George H. Booth

Subjects: Chemical Physics (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)

[88]  arXiv:2404.01312 (replaced) [pdf, ps, other]

Title: Note: Bridging Information Science: AB Initio Calculation Vortex of 2D Materials of Bismuthene(Bismuth Molecule) Graphene-Shaped through Kohn-Sham Equations

Authors: Yasuko Kawahata

Comments: AB Initio Calculation, First-Principles Calculations, Graphene, Plumbene, Kohn-Sham equations, 2D Honeycomb Materials, Arsenene, Antimonene, Tellurene, Plumbene, Silane, Monosilane, Silicene, Bismuthene, Bismuth Molecule, Vortex, Nonlinear optical response, Digital Information Control, Density Functional Theory, Twisted Bilayer Structures

Subjects: Materials Science (cond-mat.mtrl-sci)

[89]  arXiv:2404.12939 (replaced) [pdf, other]

Title: Superradiant phase transition in a large interacting driven atomic ensemble in free space

Authors: Janne Ruostekoski

Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph); Optics (physics.optics)

[90]  arXiv:2404.16704 (replaced) [pdf, other]

Title: Fidelity and criticality in the nonreciprocal Aubry-Andr{é}-Harper model

Authors: Chen-Chang Zeng, Zhen Cai, Guang-Heng Wang, Gaoyong Sun

Comments: 7 pages, 4 figures

Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn)

[91]  arXiv:2404.16774 (replaced) [pdf, other]

Title: Imaginary Stark Skin Effect

Authors: Heng Lin, Jinghui Pi, Yunyao Qi, Gui-Lu Long

Comments: 5+9 pages 4+6 figures

Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas)

[92]  arXiv:2404.17320 (replaced) [pdf, other]

Title: Percolative supercurrent in superconductor-ferromagnetic insulator bilayers

Authors: A. Maiani, A. C. C. Drachmann, L. Galletti, C. Schrade, Y. Liu, R. Seoane Souto, S. Vaitiekėnas

Comments: 15 pages, 4+7 figures

Subjects: Superconductivity (cond-mat.supr-con); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

[93]  arXiv:2404.18329 (replaced) [pdf, other]

Title: Quantized Born Effective charges as probes for the topological phase transition in the Haldane and Kane-Mele models

Authors: Paolo Fachin, Francesco Macheda, Paolo Barone, Francesco Mauri

Subjects: Materials Science (cond-mat.mtrl-sci)

[94]  arXiv:2404.18683 (replaced) [pdf, ps, other]

Title: New tool for extraction of $^{187}$Os Mössbauer parameters with biologically relevant detection sensitivity

Authors: Iryna Stepanenko, Zhishuo Huang, Liviu Ungur, Dimitrios Bessas, Aleksandr Chumakov, Ilya Sergueev, Gabriel E. Büchel, Abdullah A. Al-Kahtani, Liviu Chibotaru, Joshua Telser, Vladimir B. Arion

Comments: 21 pages, 3 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

[95]  arXiv:2404.18709 (replaced) [pdf, other]

Title: Three-state Opinion Dynamics for Financial Markets on Complex Networks

Authors: Bernardo J. Zubillaga, Mateus F. B. Granha, André L. M. Vilela, Chao Wang, Kenric P. Nelson, H. Eugene Stanley

Comments: 15 pages, 14 figures

Subjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech); General Economics (econ.GN)

[96]  arXiv:2404.18916 (replaced) [pdf, ps, other]

Title: Observation of Generalized t-J Spin Dynamics with Tunable Dipolar Interactions

Authors: Annette N. Carroll, Henrik Hirzler, Calder Miller, David Wellnitz, Sean R. Muleady, Junyu Lin, Krzysztof P. Zamarski, Reuben R. W. Wang, John L. Bohn, Ana Maria Rey, Jun Ye

Subjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)

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