CMP Journal 2025-07-04
Statistics
arXiv: 60
arXiv
Nano-optomechanical exploration of the dynamical photothermal response of suspended nanowires to laser-induced thermal waves
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Gouriou Clément, Dousset Cattleya, Fontana Alex, Reigue Antoine, Fogliano Francesco, Weltz Hugo, Judéaux Lucas, Croquette Michael, Pigeau Benjamin, Arcizet Olivier
Thermal and photothermal effects play an increasing role at the nanoscale due to the general decrease of thermal conductances and to the increasing role of interfaces. Here we present a non-contact optomechanical analysis of the thermal and photothermal properties of suspended nanowires based on pump-probe response measurements: a probe laser measures the nanowire deformations and property changes caused by an intensity-modulated pump laser launching thermal waves propagating along the 1D conductor. The analysis of the dominant photothermal contributions to the nanowires response in the spectral and spatial domains allows in particular to quantify the interfacial contact resistance, to detect its internal optical resonances and to image absorption inhomogeneities. Additionally, by exploiting the temperature-induced optical reflectivity changes of the nanowire, we directly image the spatial structure of the thermal waves propagating within the nanowire. Finally we investigate how those thermal waves are responsible for a dynamical modulation of the nanowire vibration frequency, in the resolved sideband regime, providing novel analytical tools to further inspect the structural properties of nano-optomechanical systems with a large signal to noise ratio. Those methods are generic and critical to correctly understand the photothermal dynamical back action processes and improve the intrinsic sensitivity of those ultrasensitive force probes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Thermodynamics: A Clear Conceptual Framework
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-04 20:00 EDT
Building on the fundamental equation, this study revisits key thermodynamic concepts in a cohesive and innovative manner. It demonstrates the consistency of thermodynamic theory while addressing and clarifying common misconceptions and errors found in the literature, particularly regarding discussions on heat and work. Although the latter two concepts could potentially be set aside, they can be retained if their various and different definitions are clearly articulated and properly understood. The proposed theoretical framework was tested using the free expansion of an ideal gas, a particularly demanding example due to its abrupt nature. From an educational standpoint, this article is invaluable as it consolidates fundamental yet often subtle concepts in an assertive and comprehensible way. Furthermore, it promotes a clearer and more accessible understanding of thermodynamics, challenging the widespread notion that is inherently difficult to grasp.
Statistical Mechanics (cond-mat.stat-mech)
14 pages, 4 figures, 2 tables
Hall-on-Toric: Descendant Laughlin state in the chiral $\mathbb{Z}_p$ toric code
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Robin Schäfer, Claudio Chamon, Chris R. Laumann
We demonstrate that the chiral $ \mathbb{Z}_p$ toric code – the quintessential model of topological order – hosts additional, emergent topological phases when perturbed: descendant fractional quantum Hall-like states, which we term \textit{Hall-on-Toric}. These hierarchical states feature fractionalized $ \mathbb{Z}_p$ charges and increased topological ground-state degeneracy. The Hall-on-Toric phases appear in the vicinity of the transitions between deconfined $ \mathbb{Z}_p$ phases with different background charge per unit cell, in a fixed non-trivial flux background. We confirm their existence through extensive infinite density matrix renormalization group (iDMRG) simulations, analyzing the topological entanglement entropy, entanglement spectra, and a generalized Hall conductance. Remarkably, the Hall-on-Toric states remain robust even in the absence of $ U(1)$ symmetry. Our findings reinforce the foundational interpretation of star and plaquette defects as magnetic and electric excitations, and reveal that this perspective extends to a much deeper level.
Strongly Correlated Electrons (cond-mat.str-el)
Spacetime symmetry-enriched SymTFT: from LSM anomalies to modulated symmetries and beyond
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Salvatore D. Pace, Ömer M. Aksoy, Ho Tat Lam
We extend the Symmetry Topological Field Theory (SymTFT) framework beyond internal symmetries by including geometric data that encode spacetime symmetries. Concretely, we enrich the SymTFT of an internal symmetry by spacetime symmetries and study the resulting symmetry-enriched topological (SET) order, which captures the interplay between the spacetime and internal symmetries. We illustrate the framework by focusing on symmetries in 1+1D. To this end, we first analyze how gapped boundaries of 2+1D SETs affect the enriching symmetry, and apply this within the SymTFT framework to gauging and detecting anomalies of the 1+1D symmetry, as well as to classifying 1+1D symmetry-enriched phases. We then consider quantum spin chains and explicitly construct the SymTFTs for three prototypical spacetime symmetries: lattice translations, spatial reflections, and time reversal. For lattice translations, the interplay with internal symmetries is encoded in the SymTFT by translations permuting anyons, which causes the continuum description of the SymTFT to be a foliated field theory. Using this, we elucidate the relation between Lieb-Schultz-Mattis (LSM) anomalies and modulated symmetries and classify modulated symmetry-protected topological (SPT) phases. For reflection and time-reversal symmetries, the interplay can additionally be encoded by symmetry fractionalization data in the SymTFT, and we identify mixed anomalies and study gauging for such examples.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
60 pages plus appendices
Quantum Geometry in the NbSe$_2$ Family I: Obstructed Compact Wannier Function and New Perturbation Theory
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Jiabin Yu, Yi Jiang, Yuanfeng Xu, Dumitru Călugăru, Haoyu Hu, Haojie Guo, Sandra Sajan, Yongsong Wang, Miguel M. Ugeda, Fernando De Juan, B. Andrei Bernevig
We revisit the electronic structure and band topology of monolayer 1H-NbSe$ _2$ , which hosts both superconductivity and charge density wave, and its related compounds 1H-MoS$ _2$ , NbS$ _2$ , TaS$ _2$ , TaSe$ _2$ and WS$ _2$ . We construct a 6-band, a 3-band, and - simplest of all - a single-band model for this material family, by directly Wannierizing the ab initio bands. All host obstructed atomic isolated bands away from the atomic positions near the Fermi energy. We find that in the 3-band model, the obstructed atomic Wannier function can be well approximated by an optimally compact Wannier function with more than 90% accuracy for all the compounds, rising to a remarkable 94% accuracy in NbSe$ _2$ . Interestingly, the simplest single-band model has next nearest-neighboring hopping larger than the nearest-neighboring hopping (by nearly an order of magnitude for MoS$ _2$ , NbSe$ _2$ , TaSe$ _2$ and WS$ _2$ ), which comes from the cancellation between the atomic onsite terms and the atomic nearest-neighboring hopping after projecting to the obstructed atomic Wannier functions. Furthermore for NbSe$ _2$ , we employ a novel approximation scheme to obtain an effective Hamiltonian that captures the 3 bands originating mainly from the Nb atom. We also use conventional perturbation theory to derive the ab initio obstructed Wannier function with 95% accuracy. Our results pave the way for future study of the effect of quantum geometry on the correlated phases in this family of materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
9+38 pages, 2+11 figures, 0+2 tables. See previously posted arXiv:2501.09063
Unconventional Spintronics from Chiral Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Yuntian Liu, Reshna Shrestha, Konstantin Denisov, Denzel Ayala, Mark van Schilfgaarde, Wanyi Nie, Igor Žutić
Spintronic devices typically employ heterostructures with ferromagnets which break time-reversal symmetry and have non-vanishing magnetization. With the growing class of materials that support spin-polarized carriers, current, and excitations,it is possible to envision emerging spintronic applications that are not limited to magnetoresistance. Here we focus on chiral perovskites with no net magnetization where the space-inversion and mirror symmetries are broken to induce chiral structure. The known importance of these perovskites is further expanded by the demonstration of the chiral-induced spin selectivity (CISS). However, the generation of the spin-polarized carriers across the interface with these chiral perovskites remains to be fully understood. Our first-principles studies for two-dimensional PbBr$ _4$ -based chiral perovskites provide their electronic structure and an orbital-based symmetry analysis, which allows us to establish an effective Hamiltonian to elucidate the underlying origin of their chirality. We also use this analysis for the Edelstein effect, responsible for electrical generation of the nonequilibrium spin polarization in many materials, which in chiral perovskites could be a mechanism contributing to CISS. Furthermore, by examining optical properties of chiral perovskites and the opportunity to use them to realize tunable altermagnets, another class of zero-magnetization spintronic materials, we put forth a versatile materials platform for unconventional spintronics.
Materials Science (cond-mat.mtrl-sci)
Invited article, to appear in Advanced Functional Materials
Periodically Driven anharmonic chain: Convergent Power Series and Numerics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-04 20:00 EDT
Pedro L. Garrido, Tomasz Komorowski, Joel L. Lebowitz, Stefano Olla
We investigate the long time behavior of a pinned chain of $ 2N+1$
oscillators, indexed by $ x \in{-N,\ldots, N}$ . The system is subjected to an external driving force on the particle at $ x=0$ , of period $ \theta=2\pi/\omega$ , and to frictional
damping $ \gamma>0$ at both endpoints $ x=-N$ and $ N$ .
The oscillators interact with a pinned and nearest neighbor harmonic
plus anharmonic potentials of the form
$ \frac{\omega_0^2 q_x^2}{2}+\frac12 (q_{x}-q_{x-1})^2 +\nu\left[V(q_x)+U(q_x-q_{x-1}) \right]$ , with $ V’’$ and $ U’’$
bounded and $ \nu\in \mathbb{R}$ .
We recall the recently proven convergence and the global stability of
a perturbation series in powers of $ \nu$ for
$ |\nu| < \nu_0$ , yielding the long time periodic state of the
system.
Here $ \nu_0$ depends only on the supremum norms of $ V’’$ and $ U’’$
and the distance of the set of non-negative integer multiplicities of
$ \omega$ from the interval $ [\omega_0,\sqrt{\omega_0^2+4}]$ - the spectrum of
the infinite harmonic chain for $ \nu=0$ . We describe also some numerical studies of this system going beyond our rigorous results.
Statistical Mechanics (cond-mat.stat-mech)
19 pages, 13 figures
Quantum Hall Andreev Conversion in Graphene Nanostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Alexey Bondarev, William H. Klein, Harold U. Baranger
We study Andreev conversion in clean nanostructures containing an interface between graphene in the quantum Hall (QH) state and a superconductor, focusing on the lowest Landau level. First, several graphene nanostructures formed from zigzag edges with sharp corners are considered using a tight-binding model. We find the scattering state for an electron impinging on the interface from the upstream QH edge state, together with the probability of it exiting as a hole in the downstream QH edge state (Andreev conversion). From these results, we deduce the behavior for edges at an arbitrary angle and for rounded corners. A key issue is whether the graphene-superconductor interface is fully transparent or only partially transparent. For full transparency, we recover previous results. In contrast, interfaces with partial but substantial transparency (well away from the tunneling limit) behave very differently: (i) the hybrid electron-hole interfacial modes are not valley degenerate and (ii) intervalley scattering can occur at the corners, even when rounded. As a result, interference between the two hybrid modes can occur, even in the absence of disorder. Finally, we compare the sensitivity of Andreev conversion to interface transparency in the QH regime to that in the absence of a magnetic field. While the zero-field result closely follows the classic Blonder-Tinkham-Klapwijk relation, Andreev conversion in the QH regime is considerably more robust.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
14 pages + 4 supplementary (21 figs)
Unlocking Quantum Control and Multi-Order Correlations via Terahertz Two-Dimensional Coherent Spectroscopy
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
Chuankun Huang, Martin Mootz, Liang Luo, Ilias E. Perakis, Jigang Wang
Terahertz two-dimensional coherent spectroscopy (THz-2DCS) is transforming our ability to probe, visualize, and control quantum materials far from equilibrium. This emerging technique brings multi-dimensional resolution to the ultrafast dynamics of nonequilibrium phases of matter, enabling new capabilities demanding precise coherent control and measurement of many-body dynamics and multi-order correlations. By mapping complex excitations across time and frequency dimensions, THz-2DCS delivers coherence tomography of driven quantum matter, thus revealing hidden excitation pathways, measuring higher order nonlinear response functions, disentangling various quantum pathways, capturing collective modes on ultrafast timescales and at terahertz frequencies. These experimental features frequently remain obscured in traditional single particle measurements, ultrafast spectroscopy techniques, and equilibrium-based probes. This Review traces the early development of THz-2DCS and showcases significant recent progress in leveraging this technique to probe and manipulate quantum material properties, including nonequilibrium superconductivity, nonlinear magnonics, dynamical topological phases, and the detection of novel excitations and exotic collective modes with potential technological impact. Looking forward, we identify critical opportunities in advancing THz-2DCS instrumentation and experimental strategies that are shaping future applications in THz optoelectronics, quantum information processing, and sensing.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
An alternative approach to the phonon theory of liquids: Evolution of the energy of diffusion
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
M. Y. Esmer, Bahtiyar A. Mamedov
With regard to the three basic states of matter (solid, liquid, gas), the calculation of the heat capacity of liquids in a general form has been considered one of the deepest and most interesting challenges in condensed matter physics, due to the strong, system-specific interactions involved. Notwithstanding the theoretical difficulties, there have recently been significant advances in our understanding of liquids, and the phonon theory of liquids has been proposed. However, this theory uses the virial theorem to calculate the liquid energy. Here, we propose an alternative version of the phonon theory of liquids by taking into account the numbers of oscillating atoms and diffusing atoms, rather than using the virial theorem. A new formula is derived for the liquid energy in both the quantum and the classical anharmonic cases. To verify the proposed approach, theoretical predictions are compared with the experimental specific heat of liquid mercury. Finally, we obtain a new expression for the energy of a supercritical system.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
13 pages, 2 figures
Engineering Quantum Wire States for Atom Scale Circuitry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Max Yuan, Lucian Livadaru, Roshan Achal, Jason Pitters, Furkan Altincicek, Robert Wolkow
Recent advances in hydrogen lithography on silicon surfaces now enable the fabrication of complex and error-free atom-scale circuitry. The structure of atomic wires, the most basic and common circuit elements, plays a crucial role at this scale, as the exact position of each atom matters. As such, the characterization of atomic wire geometries is critical for identifying the most effective configurations. In this study, we employed low-temperature (4.5 K) scanning tunneling microscopy (STM) and spectroscopy (STS) to systematically fabricate and characterize six planar wire configurations made up of silicon dangling bonds (DBs) on the H-Si(100) surface. Crucially, the characterization was performed at the same location and under identical tip conditions, thereby eliminating artifacts due to the local environment to reveal true electronic differences among the line configurations. By performing dI/dV line spectroscopy on each wire, we reveal their local density of states (LDOS) and demonstrate how small variations in wire geometry affect orbital hybridization and induce the emergence of new electronic states. Complementarily, we deploy density functional theory (DFT) and non-equilibrium Green’s functions to compute the LDOS and evaluate transmission coefficients for the most promising wire geometries. Our results indicate that dimer and wider wires exhibit multiple discrete mid-gap electronic states which could be exploited for signal transport or as custom quantum dots. Furthermore, wider wires benefit from additional current pathways and exhibit increased transmission, while also demonstrating enhanced immunity to hydrogen defects.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Article: 18 pages, 6 figures, and 1 table. Supplementary information: 9 pages, and 14 SI figures
Tuning Incommensurate Charge Order in Ba$_{1-x}$Sr$_x$Al$4$ and Ba${1-y}$Eu$_y$Al$_4$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Prathum Saraf, Eleanor M. Clements, Danila Sokratov, Shanta Saha, Peter Zavalij, Thomas W. Heitmann, Jeffrey W. Lynn, Camille Bernal-Choban, Dipanjan Chaudhuri, Caitlin Kengle, Yue Su, Simon Bettler, Nathan Manning, Peter Abbamonte, Sananda Biswas, Roser Valentí, Johnpierre Paglione
The BaAl$ _4$ -type structure family is home to a vast landscape of interesting and exotic properties, with descendant crystal structures hosting a variety of electronic ground states including magnetic, superconducting and strongly correlated electron phenomena. BaAl$ _4$ itself hosts a non-trivial topological band structure, but is otherwise a paramagnetic metal. However, the other members of the $ A$ Al$ _4$ family ($ A$ = alkali earth), including SrAl$ _4$ and EuAl$ _4$ , exhibit symmetry-breaking ground states including charge density wave (CDW) and magnetic orders. Here we investigate the properties of the solid solution series Ba$ _{1-x}$ Sr$ _x$ Al$ _4$ and Ba$ _{1-y}$ Eu$ _y$ Al$ _4$ using transport, thermodynamic and scattering experiments to study the evolution of the charge-ordered state as it is suppressed with Ba substitution to zero near 50% substitution in both systems. Neutron and x-ray diffraction measurements reveal an incommensurate CDW state in SrAl$ _4$ with $ c$ -axis-oriented ordering vector (0, 0, 0.097) that evolves with Ba substitution toward a shorter wavelength. A similar progression is observed in the Ba$ _{1-y}$ Eu$ _y$ Al$ _4$ series that also scales with the ordering temperature, revealing a universal correlation between charge-order transition temperature and ordering vector that points to a critical wavevector that stabilizes CDW order in both systems. We study the evolution of the phonon band structure in the Ba$ _{1-x}$ Sr$ _x$ Al$ _4$ system, revealing the suppression of the CDW phase matches the suppression of a phonon instability at precisely the same momentum as observed in experiments, confirming the electron-phonon origin of charge order in this system.
Strongly Correlated Electrons (cond-mat.str-el)
Coercivity-size map of magnetic nanoflowers: spin disorder tunes the vortex reversal mechanism and tailors the hyperthermia sweet spot
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Elizabeth M Jefremovas, Lisa Calus, Jonathan Leliaert
Iron-oxide nanoflowers (NFs) are one of the most efficient nanoheaters for magnetic hyperthermia therapy (MHT). However, the physics underlying the spin texture of disordered iron-oxide nanoparticles beyond the single-domain limit remains still poorly understood. Using large-scale micromagnetic simulations we completely map the magnetization of NFs over an unprecedented size range, from 10 to 400 nm in diameter, connecting their microstructure to their macroscopic magnetic response. Above the single domain (d > 50 nm), the magnetization folds into a vortex state, within which the coercivity describes a secondary maximum, not present for non-disordered nanoparticles. We have extended our understanding by resolving also the NF magnetization dynamics, capturing the physics of the magnetization reversal. Within the vortex regime, two distinct reversal modes exist: i) A core-dominated one, in which the core immediately switches along the direction of the applied field, resulting in an increasing coercivity for larger sizes; and ii) a flux-closure dominated reversal mode, going through the perpendicular alignment of the vortex core to the field, resulting in a decreasing coercivity-size dependence. The coercivity maximum is located at the transition between both reversal modes, and results from the combination of grain anisotropy and grain-boundary pinning: weak (but non-negligible) inter-grain exchange keeps the vortex profile coherent, yet allows the core to be pinned by the random anisotropy easy axes of the single grains, maximizing magnetic losses. Our results provide the first full description of spin textures in iron oxide NFs beyond the macrospin framework, and clarify the role of internal spin disorder in magnetic hyperthermia heating. By adjusting the grain size, the coercivity “sweet spot” can be tailored, offering a practical route to next-generation, high-efficiency nanoheaters.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Supporting Information file available at the link
Is the hyperscaling relation violated below the upper critical dimension in some particular cases?
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-04 20:00 EDT
In this review, we show our results with new interpretation on the critical exponents of thin films obtained by high-performance multi-histogram Monte Carlo simulations. The film thickness $ N_z$ consists of a few layers up to a dozen of layers in the $ z$ direction. The free boundary condition is applied in this direction while in the $ xy$ plane periodic boundary conditions are used. Large $ xy$ plane sizes are used for finite-size scaling. The Ising model is studied with nearest-neighbor (NN) interaction. When $ N_z=1$ , namely the two-dimensional (2D) system, we find the critical exponents given by the renormalization group. While, for $ N_z>1$ , the critical exponents calculated with the high-precision multi-histogram technique show that they deviate slightly but systematically from the 2D values. If we use these values of critical exponents in the hyperscaling relation with $ d=2$ , then the hyperscaling relation is violated. However, if we use the hyperscaling relation and the critical exponents obtained for $ N_z>1$ to calculate the dimension of the system, we find the system dimension slightly larger than 2. This can be viewed as an “effective” dimension. More discussion is given in the paper. We also show the cross-over between the first- and second-order transition while varying the film thickness in an antiferromagnetic FCC Ising frustrated thin film. In addition, we will show evidence that when a 2D system has two order parameters of different symmetries with a single transition, the critical exponents are new, suggesting a universality class of coupled two-symmetry breakings. In this case, the 2D hyperscaling does not hold. Another case is the 3D Ising model coupled to the lattice vibration: the critical exponents deviate from the 3D Ising ones, the results suggest the violation of the hyperscaling.
Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
23 pages, 30 figures, submitted to Physica A
Superconductivity in Ternary Zirconium Telluride Zr6RuTe2
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
Kosuke Yuchi, Haruka Matsumoto, Daisuke Nishio-Hamane, Kodai Moriyama, Keita Kojima, Ryutaro Okuma, Jun-ichi Yamaura, Yoshihiko Okamoto
Zr6CoAl2-type Zr6RuTe2 is found to show bulk superconductivity below the superconducting transition temperature Tc = 1.1 K, according to the electrical resistivity, magnetization, and heat capacity measurements using synthesized polycrystalline samples. This Tc exceeds that of Zr6MTe2 compounds in which M is other transition metals, indicating that M = Ru is favorable for superconductivity in Zr6CoAl2-type Zr6MX2.
Superconductivity (cond-mat.supr-con)
3 pages, 1 figure
J. Phys. Soc. Jpn. 94, 085001 (2025)
Symmetries of electron interactions in Hubbard models of unconventional superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
We use symmetry arguments to show that the matrix elements of electron-electron interaction on a lattice reach extrema in states composed of wavevectors near high-symmetry points of the Brillouin zone. The mechanism is illustrated by minimal models of cuprates and Fe-based superconductors, where this dependence originates from the wavevector-dependent orbital composition of wavefunctions. We discuss how these dependences can facilitate finite-momentum pairing. Our results provide symmetry-based guidance for the search for new high-temperature superconductors.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Comments/suggestions are welcome
Enhancement of quantum coherence in solid-state qubits via interface engineering
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Wing Ki Lo, Yaowen Zhang, Ho Yin Chow, Jiahao Wu, Man Yin Leung, Kin On Ho, Xuliang Du, Yifan Chen, Yang Shen, Ding Pan, Sen Yang
Shallow nitrogen-vacancy (NV) centers in diamond are promising quantum sensors but suffer from noise-induced short coherence times due to bulk and surface impurities. We present interfacial engineering via oxygen termination and graphene patching, extending shallow NV coherence to over 1 ms, approaching the T1 limit. Raman spectroscopy and density-functional theory reveal surface termination-driven graphene charge transfer reduces spin noise by pairing surface electrons, supported by double electron-electron resonance spectroscopy showing fewer unpaired spins. Enhanced sensitivity enables detection of single weakly coupled 13C nuclear spins and external 11B spins from a hexagonal boron nitride (h-BN) layer, achieving nanoscale nuclear magnetic resonance. A protective h-BN top layer stabilizes the platform, ensuring robustness against harsh treatments and compatibility with target materials. This integrated approach advances practical quantum sensing by combining extended coherence, improved sensitivity, and device durability.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Nat Commun 16, 5984 (2025)
Noninvertible symmetry and topological holography for modulated SPT in one dimension
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Jintae Kim, Yizhi You, Jung Hoon Han
We examine noninvertible symmetry (NIS) in one-dimensional (1D) symmetry-protected topological (SPT) phases protected by dipolar and exponential-charge symmetries, which are two key examples of modulated SPT (MSPT). To set the stage, we first study NIS in the $ \mathbb{Z}_N \times \mathbb{Z}_N$ cluster model, extending previous work on the $ \mathbb{Z}_2 \times \mathbb{Z}_2$ case. For each symmetry type (charge, dipole, exponential), we explicitly construct the noninvertible Kramers-Wannier (KW) and Kennedy-Tasaki (KT) transformations, revealing dual models with spontaneous symmetry breaking (SSB). The resulting symmetry group structure of the SSB model is rich enough that it allows the identification of other SSB models with the same symmetry. Using these alternative SSB models and KT duality, we generate novel MSPT phases distinct from those associated with the standard decorated domain wall picture, and confirm their distinctiveness by projective symmetry analyses at their interfaces. Additionally, we establish a topological-holographic correspondence by identifying the 2D bulk theories-two coupled layers of toric codes (charge), anisotropic dipolar toric codes (dipole), and exponentially modulated toric codes (exponential)-whose boundaries host the respective 1D MSPT phases.
Strongly Correlated Electrons (cond-mat.str-el)
25 pages, 3 figures
Nodal-line semimetals and their variance
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Topological nodal-line semimetals (NLSMs) are a new family of topological materials characterized by electronic band crossings that form lines in the Brillouin zone. These NLSMs host exotic nodal-line structures and exhibit distinct features such as drumhead surface states and unique electromagnetic responses. This review classifies various NLSM types based on their nodal structures and protecting symmetries, highlighting that these nodal-line structures can form links, knots, and chains. We discuss their characteristic electromagnetic responses, including Landau level spectroscopy, optical conductivity, and permittivity. Furthermore, the strong correlation effects in these NLSMs modify their semimetallic phases and lead to novel quantum phases where magnetism and superconductivity intertwine.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Submit a review to the special issue “Topological Quantum Materials” in Materials Today Quantum. Comments are welcome
High-Throughput NEB for Li-Ion Conductor Discovery via Fine-Tuned CHGNet Potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Jingchen Lian, Xiao Fu, Xuhe Gong, Ruijuan Xiao, Hong Li
Solid-state electrolytes are essential in the development of all-solid-state batteries. While density functional theory (DFT)-based nudged elastic band (NEB) and ab initio molecular dynamics (AIMD) methods provide fundamental insights on lithium-ion migration barriers and ionic conductivity, their computational costs make large-scale materials exploration challenging. In this study, we developed a high-throughput NEB computational framework integrated with the fine-tuned universal machine learning interatomic potentials (uMLIPs), enabling accelerated prediction of migration barriers based on transition state theory for the efficient discovery of fast-ion conductors. This framework automates the construction of initial/final states and migration paths, mitigating the inaccurate barriers prediction in pretrained potentials due to the insufficient training data on high-energy states. We employed the fine-tuned CHGNet model into NEB/MD calculations and the dual CHGNet-NEB/MD achieves a balance between computational speed and accuracy, as validated in NASICON-type Li$ _{1+x}$ Al$ _x$ Ti$ _{2-x}$ (PO$ _4$ )$ _3$ (LATP) structures. Through high-throughput screening, we identified orthorhombic Pnma-group structures (LiMgPO$ _4$ , LiTiPO$ _5$ , etc.) which can serve as promising frameworks for fast ion conductors. Their aliovalent-doped variants, Li$ _{0.5}$ Mg$ _{0.5}$ Al$ _{0.5}$ PO$ _4$ and Li$ _{0.5}$ TiPO$ _{4.5}$ F$ _{0.5}$ , were predicted to possess low activation energies, as well as high ionic conductivity of 0.19 mS/cm and 0.024 mS/cm, respectively.
Materials Science (cond-mat.mtrl-sci)
Discontinuous percolation via suppression of neighboring clusters in a network
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-04 20:00 EDT
Our recent study on the Bethe lattice reported that a discontinuous percolation transition emerges as the number of occupied links increases and each node rewires its links to locally suppress the growth of neighboring clusters. However, since the Bethe lattice is a tree, a macroscopic cluster forms as an infinite spanning tree but does not contain a finite fraction of the nodes. In this paper, we study a bipartite network that can be regarded as a locally tree-like structure with long-range neighbors. In this network, each node in one of the two partitions is allowed to rewire its links to nodes in the other partition to suppress the growth of neighboring clusters. We observe a discontinuous percolation transition characterized by the emergence of a single macroscopic cluster containing a finite fraction of nodes, followed by critical behavior of the cluster size distribution. We also provide an analytical explanation of the underlying mechanism.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
7 pages, 6 figures
A statistical theory for polymer elasticity: from molecular kinematics to continuum behavior
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Lin Zhan, Siyu Wang, Rui Xiao, Shaoxing Qu, Paul Steinmann
Predicting the macroscopic mechanical behavior of polymeric materials from the micro-structural features has remained a challenge for decades. Existing theoretical models often fail to accurately capture the experimental data, due to non-physical assumptions that link the molecule kinematics with the macroscopic deformation. In this work, we construct a novel Hamiltonian for chain segments enabling a unified statistical description of both individual macromolecular chains and continuum polymer networks. The chain kinematics, including the stretch and orientation properties, are retrieved by the thermodynamic observables without phenomenological assumptions. The theory shows that the chain stretch is specified by a simple relation via its current spatial direction and the continuum Eulerian logarithmic strain, while the probability of a chain in this spatial direction is governed by the new Hamiltonian of a single segment. The model shows a significantly improved prediction on the hyperelastic response of elastomers, relying on minimal, physically-grounded parameters.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Time- and Polarization-Resolved Extreme Ultraviolet Momentum Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Sotirios Fragkos, Quentin Courtade, Olena Tkach, Jérôme Gaudin, Dominique Descamps, Guillaume Barrette, Stéphane Petit, Gerd Schönhense, Yann Mairesse, Samuel Beaulieu
We report the development of an instrument combining an ultrafast, high-repetition-rate, polarization-tunable monochromatic extreme ultraviolet (XUV, 21.6 eV) beamline and a next-generation momentum microscope endstation. This setup enables time- and angle-resolved photoemission spectroscopy of quantum materials, offering multimodal photoemission dichroism capabilities. The momentum microscope simultaneously detects the full surface Brillouin zone over an extended binding energy range. It is equipped with advanced electron optics, including a new type of front lens that supports multiple operational modes. Enhanced spatial resolution is achieved by combining the small XUV beam footprint (33 $ \mu$ m by 45 $ \mu$ m) with the selection of small regions of interest using apertures positioned in the Gaussian plane of the momentum microscope. This instrument achieves an energy resolution of 44 meV and a temporal resolution of 144 fs. We demonstrate the capability to perform linear, Fourier, and circular dichroism in photoelectron angular distributions from photoexcited 2D materials. This functionality paves the way for time-, energy-, and momentum-resolved investigations of orbital and quantum geometrical properties underlying electronic structures of quantum materials driven out of equilibrium.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Dynamic Avalanches: Rate-Controlled Switching and Race Conditions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Avalanches are rapid cascades of rearrangements driven by cooperative flipping of hysteretic local elements. Here we show that flipping dynamics and race conditions – where multiple elements become unstable simultaneously – give rise to dynamic avalanches that cannot be captured by static models of interacting elements. We realize dynamic avalanches in metamaterials with controlled flipping times, and demonstrate how this allows to modify, promote, and direct avalanche behavior. Our work elucidates the crucial role of internal dynamics in complex materials and introduces dynamic design principles for materializing targeted pathways and sequential functionalities.
Soft Condensed Matter (cond-mat.soft)
7 pages, 5 figures
Ginzburg-Landau theory for unconventional surface superconductivity in PtBi$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
Harald Waje, Fabian Jakubczyk, Jeroen van den Brink, Carsten Timm
Recent experimental evidence suggests the presence of an unconventional, nodal surface-superconducting state in trigonal PtBi\textsubscript{2}. We construct a Ginzburg–Landau theory for the three superconducting order parameters, which correspond to the three irreducible representations of the point group $ C_{3v}$ . The irreducible representations $ A_1$ and $ A_2$ are the most likely. We develop a systematic method to determine the symmetry-allowed terms and apply it to derive all terms up to fourth order in the three order parameters. The Ginzburg–Landau functional also includes coupling to the magnetic field. The functional is employed to determine the effect of an applied uniform magnetic field on the nodal structure for $ A_1$ and $ A_2$ pairing. The results facilitate clear-cut experimental differentiation between these symmetries. We also predict field-induced pair-density waves.
Superconductivity (cond-mat.supr-con)
11 pages, 1 figure
Generation of a single-cycle surface acoustic wave pulse on LiNbO$_3$ for application to thin film materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Koji Fujiwara, Shunsuke Ota, Tetsuo Kodera, Yuma Okazaki, Nobu-Hisa Kaneko, Nan Jiang, Yasuhiro Niimi, Shintaro Takada
Surface acoustic wave (SAW) technology has been explored in thin-film materials to discover fundamental phenomena and to investigate their physical properties. It is used to excite and manipulate quasi-particles such as phonons or magnons, and can dynamically modulate the properties of the materials. In the field, SAWs are typically excited by a continuous wave at a resonant frequency. Recently, generation of a single-cycle SAW pulse has been demonstrated on GaAs substrate. Such a SAW pulse provides a potential to access a single quasi-particle excitation and to investigate its dynamics by time-resolved measurements. On the other hand, to modulate and control the properties of thin film materials, it is generally required to generate high-intensity SAWs. In this work, we demonstrate the efficient generation of a SAW pulse using a chirp interdigital transducer (IDT) on LiNbO$ _3$ substrate. We have fabricated chirp IDT devices with bandwidths from 0.5 GHz to 5.5 GHz. We also confirmed the generation of a SAW pulse with 0.3 ns FWHM (full width at half maximum) by performing time-resolved measurements. The conversion efficiency between input power and SAW on LiNbO$ _3$ substrate is approximately 45 times larger than that on GaAs substrate. This enables us to generate a high-intensity SAW pulse, meeting the requirement for the modulation of thin films. Our results will expand the research in the field, such as spintronics and magnonics, and lead to their further advancements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures
Thermodynamic bounds and error correction for faulty coarse graining
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-04 20:00 EDT
Jann van der Meer, Keiji Saito
At the nanoscale, random effects govern not only the dynamics of a physical system but may also affect its observation. This work introduces a novel paradigm for coarse graining that eschews the assignment of a unique coarse-grained trajectory to a microscopic one. Instead, observations are not only coarse-grained but are also accompanied by a small chance of error. Formulating the problem in terms of path weights, we identify a condition on the structure of errors that ensures that the observed entropy production does not increase. As a result, the framework of stochastic thermodynamics for estimating entropy production can be extended to this broader class of systems. As an application, we consider Markov networks in which individual transitions can be observed but may be mistaken for each other. We motivate, derive, and illustrate thermodynamic bounds that relate the error sensitivity of the observed entropy production to the strength of the driving and are valid for arbitrary network topologies. If sufficiently many transitions in the network can be observed, redundancies in the coarse-grained trajectories can be used to detect and correct errors, which potentially improves naive estimates of entropy production. We conclude with an outlook on subsequent research on thermodynamic bounds for erroneous coarse graining.
Statistical Mechanics (cond-mat.stat-mech)
Observation of terahertz spin-Hall magnetoresistance in insulating magnet YIG/Pt
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
P. Kubaščík, R. Schlitz, O. Gueckstock, O. Franke, M. Borchert, G. Jakob, K. Olejník, A. Farkaš, Z. Kašpar, J. Jechumtál, M. Bušina, E. Schmoranzerová, P. Němec, M. Wolf, Y. Z. Wu, G. Woltersdorf, M. Kläui, P. W. Brouwer, S. T.B. Goennenwein, T. Kampfrath, L. Nádvorník
We report on the observation of spin Hall magnetoresistance (SMR) in prototypical bilayers of ferrimagnetic yttrium iron garnet (YIG) and platinum in the frequency range from 0 THz to as high as 1.5 THz. The spectral composition of the effect exhibits a strong low-pass behavior, decreasing by approximately 75% from 0 THz to 0.2 THz and vanishing entirely at 1.5 THz. Using a dynamic magnetoresistive model, we can fully explain the spectral dependence by competition of transverse spin-torque (coherent) and longitudinal (incoherent) contributions to the spin current and their characteristic response times. Our analysis suggests that the slow dissipation of incoherent magnons from the interface is the limiting process responsible for the dramatic spectral decay of the SMR. These results establish THz SMR as a powerful probe of ultrafast interfacial spin-magnon coupling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
11 pages, 4 figures
Synergistic Effects of Spin-Orbit Coupling and Intercomponent Interactions in Two-Component (2+1)D Photonic Fields
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-04 20:00 EDT
Suri Deekshita, S. Sanjay, S. Saravana Veni, Conrad B. Tabi, Timoleon C. Kofane
The study investigates the formation, stability and dynamic advancement of two-dimensional vortex quantum droplets within binary Bose-Einstein condensates (BECs), shaped by the interplay of photonic spin-orbit coupling (SOC) and quantum fluctuation effects. SOC leads to significant droplet stretching, resulting in vortex clusters forming in each component. The competition between photonic SOC and Lee-Huang-Yang (LHY) interactions introduces vortices into the condensate, described by the numerically solved Gross-Pitaevskii equation (GPE). The results show that droplets like structures arise at low SOC strengths and interaction parameters. The transition to vortex takes place as the SOC increases. Enhanced interactions give rise to the emergence of quantum droplets as the vortices dissipate, demonstrating fascinating dynamics. These findings enhance understanding of the physical properties of photonic SOC coupled binary BECs in 2D with LHY correction, impacting cold-atom physics and condensed matter research. The study can also be expanded to explore quantum droplets with a small atom count, which is advantageous for experimental applications.
Quantum Gases (cond-mat.quant-gas), Optics (physics.optics)
Spin-charge bound states and emerging fermions in a quantum spin liquid
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Jens H. Nyhegn, Kristian Knakkergaard Nielsen, Leon Balents, Georg M. Bruun
The complex interplay between charge and spin dynamics lies at the heart of strongly correlated quantum materials, and it is a fundamental topic in basic research with far reaching technological perspectives. We explore in this paper the dynamics of holes in a single band extended $ t-J$ model where the background spins form a $ \mathbb{Z}_{2}$ quantum spin liquid (QSL). Using a field theory approach based on a parton construction, we show that while the electrons for most momenta fractionalize into uncorrelated charge carrying holons and spin carrying spinons as generally expected for a QSL, the spinon-holon scattering cross-section diverges for certain momenta signalling strong correlations. By deriving an effective low-energy Hamiltonian describing this dynamics, we demonstrate that these divergencies are due to the formation of long lived spinon-holon bound states. We then show that quantum gas microscopy with atoms in optical lattices provides an excellent platform for verifying and probing the internal spatial structure of these emergent fermions. The fermions will furthermore show up as clear quasiparticle peaks in angle-resolved photoemission spectroscopy with an intensity determined by their internal structure. For a non-zero hole concentration, the fermions form hole pockets with qualitatively the same location, shape, and intensity variation in the Brillouin zone as the so-called Fermi arcs observed in the pseudogap phase. Such agreement is remarkable since the Fermi arcs arise from the delicate interplay between the symmetry of the QSL and the internal structure of the emerging fermions in a minimal single band model with no extra degrees of freedom added. Our results, therefore, provide a microscopic mechanism for the conjectured fractionalized Fermi liquid and open up new pathways for exploring the pseudogap phase and high temperature superconductivity as arising from a QSL.
Strongly Correlated Electrons (cond-mat.str-el)
Magnetic octupole Hall effect in heavy transition metals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Insu Baek, Seungyun Han, Hyun-Woo Lee
d-wave altermagnets have the magnetic octupole as their primary order parameter. A recent study [Han et al. arXiv 2409.14423 (2024)] demonstrated that magnetic octupole current can induce Néel vector dynamics. Therefore, identifying materials that can efficiently generate a magnetic octupole current is essential. In this paper, we investigate the magnetic octupole Hall effect in 4d and 5d transition metals. By employing atomic magnetic octupole operators, we calculate the magnetic octupole Hall conductivity using first-principles calculations. We also explore the microscopic origin of the magnetic octupole Hall effect and find that it results from the combined effect of orbital texture and spin-orbit coupling. Additionally, we analyze the ratio of spin Hall conductivity to magnetic octupole Hall conductivity across various materials and identify those that are optimal for observing magnetic octupole physics. We also discuss potential applications arising from the magnetic octupole Hall effect. Our work serves as a valuable reference for identifying materials suitable for studying magnetic octupole physics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 7 figures, 1 table
Triboelectric charge transfer theory driven by interfacial thermoelectric effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Ji-Ho Mun, Eui-Cheol Shin, Jaeuk Seo, Yong-Hyun Kim
Despite extensive study and the practical significance of friction-driven static electricity, a quantitative triboelectric charge transfer theory has yet to be established. Here, we elucidate the detailed dynamics of triboelectric charge transfer driven by interfacial thermoelectric bias maintaining a steady state at the interface. We demonstrate that triboelectric charge exists in a delta-like distribution at a steady state. We suggest that the transferred triboelectric charge is dictated by half of the difference between thermoelectrically induced surface charges. Moreover, we quantitatively discuss electrostatic adhesion and static discharge between the transferred charges, which we may experience every day, including the role of surface charge inhomogeneity. Our findings may have significant implications for applications ranging from static electricity phenomena to advanced energy harvesting devices.
Materials Science (cond-mat.mtrl-sci)
26 pages, 4 figures, 97 references, and 3 supplementary notes
Radiation stability of nanocomposite scintillators
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
L. Prouzova Prochazkova, F. Hajek, M. Buryi, Z. Remes, V. Cuba
Radiation hardness of scintillating nanocomposites consisting of inorganic scintillating nanocrystalline powders dispersed in organic matrices was studied under electron, X-ray and {\gamma}-ray irradiation. Samples including pure press-compacted pellets of powder ZnO:Ga and YSO:Ce, and the nanocomposites of powder ZnO:Ga and YSO:Ce embedded in polystyrene matrix with different fillings were investigated. Effects of radiation on radioluminescence and other optical properties of studied materials were evaluated. Bright burn effect related to nanocrystalline powder scintillators was observed at lower doses. Radiation damage in nanocomposite materials is related to the formation of radicals in polystyrene matrix. Extent of radiation damage decreases with ZnO:Ga filling. Presented results show the importance of systematic and complex study of the radiation stability of composite scintillators.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Aharanov-Bohm oscillations and perfectly transmitted mode in amorphous topological insulator nanowires
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Miguel F. Martínez, Adolfo G. Grushin, Jens H. Bardarson
Crystalline topological insulator nanowires with a magnetic flux threaded through their cross section display Aharanov-Bohm conductance oscillations. A characteristic of these oscillations is the perfectly transmitted mode present at certain values of the magnetic flux, due to the appearance of an effective time-reversal symmetry combined with the topological origin of the nanowire surface states. In contrast, amorphous nanowires display a varying cross section along the wire axis that breaks the effective time-reversal symmetry. In this work, we use transport calculations to study the stability of the Aharanov-Bohm oscillations and the perfectly transmitted mode in amorphous topological nanowires. We observe that at low energies and up to moderate amorphicity the transport is dominated, as in the crystalline case, by the presence of a perfectly transmitted mode. In an amorphous nanowire the perfectly transmitted mode is protected by chiral symmetry or, in its absence, by a statistical time-reversal symmetry. At high amorphicities the Aharanov-Bohm oscillations disappear and the conductance is dominated by nonquantized resonant peaks. We identify these resonances as bound states and relate their appearance to a topological phase transition that brings the nanowires into a trivial insulating phase.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn)
12 pages, 8 figures
Intriguing kagome topological materials
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
Qi Wang, Hechang Lei, Yanpeng Qi, Claudia Felser
Topological quantum materials with kagome lattice have become the emerging frontier in the context of condensedmatter physics. Kagome lattice harbors strongmagnetic frustration and topological electronic states generatedby the unique geometric this http URL has the peculiar advantages in the aspectsofmagnetism, topology aswell as strong correlationwhenthe spin, charge,ororbit degreesof free is introduced, and providing a promising platform for investigating the entangled interactionsamongthem. In this paper, we will systematically introduce the research progress on the kagome topological materials and give a perspective in the framework of the potential future development directions in this field.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 1 figure
npj Quantum Materials (2025) 10:72
Spatiotemporal hierarchy of thermal avalanches
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Vladimir Yu. Rudyak, Dor Shohat, Yoav Lahini
In amorphous solids, frustrated elastic interactions conspire with thermal noise to trigger anomalously slow sequences of plastic rearrangements, termed “thermal avalanches”, which play an important role during creep and glassy relaxations. Here we uncover the complex spatiotemporal structure of thermal avalanches in simulations of a model amorphous solid. We systematically disentangle mechanical and thermal triggering during logarithmic creep, revealing a hierarchy of fast localized cascades linked by slow, long-range, noise-mediated facilitation. These thermal avalanches exhibit heavy-tailed temporal correlations, reminiscent of seismic activity. Our work sheds light on the rich relaxation dynamics of amorphous solids, while providing a framework for identifying noise-mediated correlations. We validate this approach by revealing a similar hierarchy in experiments with crumpled thin sheets.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn)
7 pages, 5 figures
Learning and Testing Inverse Statistical Problems For Interacting Systems Undergoing Phase Transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-07-04 20:00 EDT
Stefano Bae, Dario Bocchi, Luca Maria Del Bono, Luca Leuzzi
Inverse problems arise in situations where data is available, but the underlying model is not. It can therefore be necessary to infer the parameters of the latter starting from the former. Statistical mechanics offers a toolbox of techniques to address this challenge. In this work, we illustrate three of the main methods: the Maximum Likelihood, Maximum Pseudo-Likelihood, and Mean-Field approaches. We begin with a thorough theoretical introduction to these methods, followed by their application to inference in several well-known statistical physics systems undergoing phase transitions. Namely, we consider the ordered and disordered Ising models, the vector Potts model, and the Blume-Capel model on both regular lattices and random graphs. This discussion is accompanied by a GitHub repository that allows users to both reproduce the results and experiment with new systems.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Data Analysis, Statistics and Probability (physics.data-an)
34 pages, 17 figures
A unifying approach to self-organizing systems interacting via conservation laws
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Frank Barrows, Guanming Zhang, Satyam Anand, Zizi Chen, Jonathan Lin, Amman Desai, Stefano Martiniani, Francesco Caravelli
We present a unified framework for embedding and analyzing dynamical systems using generalized projection operators rooted in local conservation laws. By representing physical, biological, and engineered systems as graphs with incidence and cycle matrices, we derive dual projection operators that decompose network fluxes and potentials. This formalism aligns with principles of non-equilibrium thermodynamics and captures a broad class of systems governed by flux-forcing relationships and local constraints. We extend this approach to collective dynamics through the PRojective Embedding of Dynamical Systems (PrEDS), which lifts low-dimensional dynamics into a high-dimensional space, enabling both replication and recovery of the original dynamics. When systems fall within the PrEDS class, their collective behavior can be effectively approximated through projection onto a mean-field space. We demonstrate the versatility of PrEDS across diverse domains, including resistive and memristive circuits, adaptive flow networks (e.g., slime molds), elastic string networks, and particle swarms. Notably, we establish a direct correspondence between PrEDS and swarm dynamics, revealing new insights into optimization and self-organization. Our results offer a general theoretical foundation for analyzing complex networked systems and for designing systems that self-organize through local interactions.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Multiagent Systems (cs.MA), Adaptation and Self-Organizing Systems (nlin.AO)
19 pages single column + 24 pages supplementary
Electron-hole tunnelling probed in de Haas - van Alphen oscillations in the (double) Dirac semimetal NbTe$_4$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Maximilian Daschner, F. Malte Grosche
NbTe$ _4$ undergoes multiple charge density wave transitions that have attracted great interest in this material for decades. Previous work has shown that the crystal obtains the space group P4/ncc (130) at temperatures below 50K which allows for the existence of eightfold degenerate double Dirac points in the band structure. We provide insights into the electronic structure of this material through density functional theory (DFT) calculations, and a rotation study of de Haas - van Alphen (dHvA) oscillations in the magnetic torque. We find that NbTe$ _4$ exhibits magnetic breakdown orbits between electron and hole pockets.
Materials Science (cond-mat.mtrl-sci)
Statistical mechanics of vector Hopfield network near and above saturation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-04 20:00 EDT
Flavio Nicoletti, Francesco D’Amico, Matteo Negri
We study analytically and numerically a Hopfield fully-connected network with $ d$ -vector spins. These networks are models of associative memory that generalize the standard Hopfield with Ising spins. We study the equilibrium and out-of-equilibrium properties of the system, considering the system in its retrieval phase $ \alpha<\alpha_c$ and beyond. We derive the Replica Symmetric solution for the equilibrium thermodynamics of the system, together with its phase diagram: we find that the retrieval phase of the network shrinks with growing spin dimension, having ultimately a vanishing critical capacity $ \alpha_c\propto 1/d$ in the large $ d$ limit. As a trade-off, we observe that in the same limit vector Hopfield networks are able to denoise corrupted input patterns in the first step of retrieval dynamics, up to very large capacities $ \widetilde{\alpha}\propto d$ . We also study the static properties of the system at zero temperature, considering the statistical properties of soft modes of the energy Hessian spectrum. We find that local minima of the energy landscape related to memory states have ungapped spectra with rare soft eigenmodes: these excitations are localized, their measure condensating on the noisiest neurons of the memory state.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
38 pages, 10 figures
Thermodynamic potentials of metallic alloys in the undercooled liquid and solid glassy states
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-07-04 20:00 EDT
A.S. Makarov, R.A. Konchakov, N.P. Kobelev, V.A. Khonik
We first present a comparative analysis of temperature evolution of the excess thermodynamic potentials (state functions), the enthalpy $ \Delta H$ , entropy $ \Delta S$ and Gibbs free energy $ \Delta \Phi$ , determined for \textit{i}) undercooled melts using literature data and \textit{ii}) solid glassy state calculated on the basis of calorimetry measurements using an approach proposed recently. Three metallic alloys were taken as an example for data analysis. It is found that temperature dependences $ \Delta H(T)$ , $ \Delta S(T)$ and $ \Delta G(T)$ calculated with both approaches coincide in the supercooled liquid range (i.e. at temperatures $ T_g<T<T_x$ , where $ T_g$ and $ T_x$ are the glass transition and crystallization onset temperatures, respectively). However, the necessary conditions for this coincidence is the introduction of important changes to the above approach \textit{i}), which are related to the calculation of the melting entropy. We also introduce and calculate a dimensionless order parameter $ \xi$ , which changes in the range $ 0<\xi<1$ and characterizes the evolution of the structural order from liquid-like to crystal-like one. It is shown that the order parameter $ \xi_{scl}$ calculated for the end of the supercooled liquid range (i.e. for a temperature just below $ T_x$ ) correlates with the melt critical cooling rate $ R_c$ : the smaller the order parameter $ \xi_{scl}$ (i.e. the closer the structure to that of the equilibrium liquid), the smaller $ R_c$ is.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
18 pages, 8 figures
Mechanical enhancement of quantum oscillations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Maximilian Daschner, Ivan Kokanović, F. Malte Grosche
We investigate quantum oscillation measurements in the Dirac nodal-line semimetal TaNiTe$ _5$ which exhibit a strongly enhanced amplitude in the magnetoresistance. We show that mechanical properties of the measurement setup in combination with de Haas - van Alphen oscillations in the magnetic torque can cause this enhancement in the measured resistance, without involvement of any topological properties in this material. To support the empirical data, a numerical model is provided, showing good agreement.
Materials Science (cond-mat.mtrl-sci)
Importance of anisotropic interactions for hard-axis/plane ordering of Ce-based ferromagnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Hanshang Jin, Rahim R. Ullah, Peter Klavins, Valentin Taufour
Ferromagnetic (FM) Kondo-lattice (KL) compounds often exhibit intriguing magnetic behavior driven by strong crystal electric field (CEF) anisotropy and exchange interactions. Recent studies suggest that many Ce-based and Yb-based KL ferromagnets order along the hard-axis or hard-plane determined by their CEF ground state. We performed a survey of Ce-based FM compounds, complemented with new single crystal synthesis, magnetization measurements, and analysis of the CEF scheme. Our results reveal that hard-axis/plane ordering is less common than previously reported, with most compounds ordering along their easy-axis/plane. We also find no clear correlation between the strength of the Kondo effect and whether a compound adopts hard-axis/plane or easy-axis/plane ordering. Instead, the key driver appears to be the competition between CEF anisotropy and exchange interaction anisotropy. A direct comparison of CeCuSi and CeAgSb$ _2$ further indicates that antiferromagnetic (AFM) interactions along the CEF easy-axis can be crucial in stabilizing the hard-axis FM ordering observed in CeAgSb$ _2$ . Finally, our results suggest that an anisotropic Ruderman-Kittel-Kasuya-Yosida (RKKY) model could offer deeper insights into the complicated magnetic properties of Ce-based and other heavy-fermion systems.
Strongly Correlated Electrons (cond-mat.str-el)
Accepted by PRB
Interplay of frustration and quantum fluctuations in a spin-1/2 anisotropic square lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
L. M. Ramos, F. M. Zimmer, M. Schmidt
Motivated by theoretical and experimental studies reported by Yamaguchi et al. (Phys. Rev. B 98, 094402 (2018)), we performed a cluster mean-field analysis of an anisotropic Heisenberg model with six competing exchange interactions. We study the ground and thermal states by tuning the spin anisotropy, magnetic field, and temperature. Our results show that an external magnetic field induces quantum fluctuations, suppressing local moments and leading to the occurrence of a magnetization plateaulike state. When weak spin anisotropy is considered, the competing interactions are affected, and the field-induced fluctuations can lead to a well-defined magnetization plateau within a field range, in which an exotic quantum state can emerge. This state exhibits the coexistence of ferromagnetic and dimerized chains driven by the relation between frustration and the external field. Moreover, we identify a phase transition from a collinear antiferromagnetic order to a disordered state at a finite temperature. Our findings reveal unconventional magnetic properties at low temperatures that can guide future experimental studies of verdazyl-based compounds with anisotropic exchange interactions.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
9 pages, 8 figures
Phys. Rev. B 112, 014402, 2025
The covariance matrix spectrum of correlated charge insulators reveals hidden connections to Coupled Cluster, Matrix Product, and Rokhsar-Kivelson states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Charge ordering induced by strong short-range repulsion in itinerant fermion systems typically follows a two-sites alternation pattern. However, the covariance matrix spectrum of the one-dimensional, half-filled, spinless $ t$ -$ V$ model reveals a post-Hartree-Fock picture at strong repulsion, with emergent four-site disruptions of the underlying staggered mean-field state. These disruptions are captured in a thermodynamically extensive manner by a compact four-fermion Coupled Cluster (doubles) state (CCS). Remarkably, all properties of this state may be computed analytically by combinatorial means, and also derived from an exactly solvable correlated hopping Hamiltonian. Furthermore, this Coupled Cluster state can be re-expressed as a low-rank Matrix Product State (MPS) with bond dimension exactly four. In addition, we unveil a hidden connection between this Coupled Cluster ansatz and a Rokhsar-Kivelson state (RKS), which is the ground state of a solvable parent quantum tetramer model. The broad picture that we uncover here thus provides deep connections between several core concepts of correlated fermions and quantum chemistry that have previously enjoyed limited synergy. In contrast to a recent perturbative treatment on top of Hartree-Fock theory, our approach asymptotically captures the correct correlations in the $ t$ -$ V$ model at small $ t/V$ , and remains a qualitatively accurate approximation even outside the perturbative regime. Our results make the case for further studies of the covariance matrix for correlated electron systems in which ground states have non-trivial unit-cell structure.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech)
14+11 pages, 7 figures
Pressure-induced band gap energy increase in crystalline lactose
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Lactose is widely used in agri-food and pharma industries. New materials that can be obtained from renewable sources are currently being sought. I have studied the effect of hydrostatic pressure on structural properties of currently known forms of crystalline lactose within the framework of density functional theory with van der Waals interactions. The computed parameters have good agreement with experimental data. The effect of mechanical deformations on electron structure of crystalline lactose was also studied. Compression of the crystal leads to the band gap increase. The analysis of partial density of states of lactose crystals was performed. The band gap of different forms of crystalline lactose was also computed using the quasiparticle G0W0 approximation.
Materials Science (cond-mat.mtrl-sci)
Radical scaling: beyond our feet and fingers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Marc-Antoine Fardin, Mathieu Hautefeuille, Vivek Sharma
Scaling laws arise and are eulogized across disciplines from natural to social sciences for providing pithy, quantitative, scale-free', and universal’ power law relationships between two variables. On a log-log plot, the power laws display as straight lines, with a slope set by the exponent of the scaling law. In practice, a scaling relationship works only for a limited range, bookended by crossovers to other scaling laws. Leading with Taylor’s oft-cited scaling law for the blast radius of an explosion against time, and by collating an unprecedented amount of datasets for laser-induced, chemical and nuclear explosions, we show distinct kinematics arise at the early and late stages. We illustrate that picking objective scales for the two axes using the transitions between regimes leads to the collapse of the data for the two regimes and their crossover, but the third regime is typically not mapped to the master curve. The objective scales permit us to abandon the arbitrarily chosen anthropocentric units of measurement, like feet for length and heart-beat for time, but the decimal system with ten digits (fingers) is still part of the picture. We show a remarkable collapse of all three regimes onto a common master curve occurs if we replace the base 10 by a dimensionless radix that combines the scales from the two crossovers. We also illustrate this approach of radical scaling for capillarity-driven pinching, coalescence and spreading of drops and bubbles, expecting such generalizations will be made for datasets across many disciplines.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
10 pages, 5 figures, 34 pages of supplementary information
Single Photon Emitters in Ultra-Thin Hexagonal Boron Nitride Layers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Le Liu, Igor Khanonkin, Johannes Eberle, Bernhard Rizek, Stefan Fält, Kenji Watanabe, Takashi Taniguchi, Ataç Imamoğlu, Martin Kroner
Single-photon emitters (SPE) in hexagonal boron nitride (h-BN) are promising for applications ranging from single-photon sources to quantum sensors. Previous studies exclusively focused on the generation and characterization of SPEs in relatively thick h-BN layers ($ \geq$ 30 nm). However, for electrical and magnetic sensing applications, the thickness of the h-BN limits the attainable spatial resolution. Here, we report the observation of blue-wavelength emitters (B-centers) activated by electron beam irradiation in ultra-thin ($ \simeq$ 3 nm) h-BN. These SPEs in ultra-thin flakes exhibit reduced brightness, broader zero-phonon line, and enhanced photobleaching. Remarkably, upon encapsulation in thicker h-BN, we restore their brightness, narrow linewidth 230$ \mu$ eV at 5K, resolution limited), suppress photobleaching, and confirm single-photon emission with $ g^{(2)}(0) < 0.4$ at room temperature. The possibility of generating SPEs in a few-layer h-BN and their subsequent incorporation into a van der Waals heterostructure paves the way for achieving quantum sensing with unprecedented nanometer-scale spatial resolution.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
Optimal boron-doped graphene substrate for glucose Raman signal enhancement
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Jan Komeda, Antonio Cammarata, Tomas Polcar
Surface Enhanced Raman Spectroscopy (SERS) is a highly sensitive and selective technique that greatly enhances the signal of an analyte, compared with its signal from classical Raman Spectroscopy, due to its interaction with a substrates surface. It has been shown that low concentration boron-doped graphene (B-graphene) enhances the Raman signal of simple organic molecules like pyridine. Recent studies also suggest that B-graphene can remain thermodynamically stable when doped with significantly higher concentrations of boron than previously observed. In this framework, we use quantum mechanical simulations to investigate the influence of dopant concentration and geometric distribution on the effectiveness of B-doped graphene as a SERS substrate, with glucose as analyte. By combining analysis of interatomic force constants and of phonon eigenvectors composition, we conclude that higher doping concentrations provide a larger enhancement to glucose’s Raman signal, while the molecule orientation relative to the surface plays a fundamental role in the Raman response. We suggest that high concentration B-graphene presents itself as a potential substrate for SERS based detection of glucose, while the used phonon-based analysis can be promptly applied for the search of promising candidates as substrate materials for enhanced Raman response.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
Solving the Hubbard model with Neural Quantum States
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Yuntian Gu, Wenrui Li, Heng Lin, Bo Zhan, Ruichen Li, Yifei Huang, Di He, Yantao Wu, Tao Xiang, Mingpu Qin, Liwei Wang, Dingshun Lv
The rapid development of neural quantum states (NQS) has established it as a promising framework for studying quantum many-body systems. In this work, by leveraging the cutting-edge transformer-based architectures and developing highly efficient optimization algorithms, we achieve the state-of-the-art results for the doped two-dimensional (2D) Hubbard model, arguably the minimum model for high-Tc superconductivity. Interestingly, we find different attention heads in the NQS ansatz can directly encode correlations at different scales, making it capable of capturing long-range correlations and entanglements in strongly correlated systems. With these advances, we establish the half-filled stripe in the ground state of 2D Hubbard model with the next nearest neighboring hoppings, consistent with experimental observations in cuprates. Our work establishes NQS as a powerful tool for solving challenging many-fermions systems.
Strongly Correlated Electrons (cond-mat.str-el), Artificial Intelligence (cs.AI), Quantum Physics (quant-ph)
Spatiotemporal Mapping of Anisotropic Thermal Transport in GaN Thin Films via Ultrafast X-ray Diffraction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Thanh Nguyen, Chuliang Fu, Mouyang Cheng, Buxuan Li, Tyra E. Espedal, Zhantao Chen, Kuan Qiao, Kumar Neeraj, Abhijatmedhi Chotrattanapituk, Denisse Cordova Carrizales, Eunbi Rha, Tongtong Liu, Shivam N. Kajale, Deblina Sarkar, Donald A. Walko, Haidan Wen, Svetlana V. Boriskina, Gang Chen, Jeehwan Kim, Mingda Li
Efficient thermal management is essential for the reliability of modern power electronics, where increasing device density leads to severe heat dissipation challenges. However, in thin-film systems, thermal transport is often compromised by interfacial resistance and microscale defects introduced during synthesis or transfer, which are difficult to characterize using conventional techniques. Here we present a non-contact, spatiotemporal-resolved ultrafast x-ray diffraction method to extract in-plane thermal conductivity and thermal boundary conductance, using GaN thin films on silicon as a model system. By tracking the pump-induced lattice strain, we reconstruct the lateral heat flow dynamics and quantitatively probe thermal transport near a wrinkle defect. We uncover pronounced asymmetric heat dissipation across the wrinkle, with a four-fold reduction in the local thermal conductivity near the wrinkle and a 25% drop in interfacial conductance. Our work demonstrates that ultrafast x-ray diffraction can serve as a precise thermal metrology tool for characterizing heat transport in multilayered thin-film structures for next-generation microelectronic devices.
Materials Science (cond-mat.mtrl-sci)
24 pages, 4 figures
A finite element implementation of a large deformation gradient-damage theory for fracture with Abaqus user material subroutines
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-07-04 20:00 EDT
Keven Alkhoury, Shawn A. Chester, Vikas Srivastava
Recent advancements in computations have enabled the application of various modeling approaches to predict fracture and failure, such as the gradient-damage (phasefield) method. Several existing studies have leveraged the heat equation solver in Abaqus to model gradient-damage, due to its mathematical resemblance to the heat equation. Particular care is required when extending the approach to large deformation scenarios due to differences in the referential and spatial configurations, especially since the heat equation in Abaqus is solved in the spatial configuration, whereas most gradient-damage frameworks are formulated in the referential configuration. This work provides a pedagogic view of an appropriate Abaqus implementation of a gradient-damage theory for fracture in materials undergoing large deformation using Abaqus UMAT and UMATHT user subroutines. Key benchmark problems from the literature are used to demonstrate the robustness of our implementation across various materials exhibiting different constitutive behaviors, such as non-linear elasticity, linear elasticity, and large deformation rate-dependent plasticity, ensuring its applicability regardless of the specific material constitutive choice. The details of the implementation, along with the codes, which are a direct outcome of this work, are also provided.
Soft Condensed Matter (cond-mat.soft)
Diffusive charge transport in the gapped 1D Hubbard model at all finite temperatures
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
J.M.P. Carmelo, P.D. Sacramento
Studies relying on hydrodynamic theory and Kardar-Parisi-Zhang (KPZ) scaling have found that in the one-dimensional Hubbard model spin and charge transport are for all temperatures T > 0 anomalous superdiffusive at zero magnetic field, h = 0, and zero chemical potential, {\mu} = 0, respectively. However, this contradicts recent exact results that at very low temperature charge transport rather is normal diffusive. In this Letter we identify the mechanisms that control the different types of temperature dependence of the h = 0 spin and {\mu} = 0 charge transport and find that the latter is normal diffusive for all finite temperatures T > 0, in contrast to the hydrodynamic theory and KPZ scaling predictions.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 2 figures plus Supplementary Material
Physical Review B 111, L241117 (2025)
Spin Caloritronics in irradiated chiral ferromagnetic systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Sudin Ganguly, Moumita Dey, Santanu K. Maiti
We study the charge and spin-dependent thermoelectric response of a ferromagnetic helical system irradiated by arbitrarily polarized light, using a tight-binding framework and the Floquet-Bloch formalism. Transport properties for individual spin channels are determined by employing the non-equilibrium Green’s function technique, while phonon thermal conductance is evaluated using a mass-spring model with different lead materials. The findings reveal that that light irradiation induces spin-split transmission features, suppresses thermal conductance, and yields favorable spin thermopower and figure of merit (FOM). The spin FOM consistently outperforms its charge counterpart under various light conditions. Moreover, long-range hopping is shown to enhance the spin thermoelectric performance, suggesting a promising strategy for efficient energy conversion in related ferromagnetic systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
15 pages, 7 figures. Comments are Welcome
Analytic Phase Solution and Point Vortex Model for Dipolar Quantum Vortices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-07-04 20:00 EDT
We derive an analytic expression for the phase of a quantum vortex in a dipolar Bose-Einstein condensate, capturing anisotropic effects from long-range dipole-dipole interactions. This solution provides a foundation for a dipolar point vortex model (DPVM), incorporating both phase-driven flow and dipolar forces. The DPVM reproduces key features of vortex pair dynamics seen in full simulations, including anisotropic velocities, deformed orbits, and directional motion, offering a minimal and accurate model for dipolar vortex dynamics. Our results open the door to analytic studies of vortices in dipolar quantum matter and establish a new platform for exploring vortex dynamics and turbulence in these systems.
Quantum Gases (cond-mat.quant-gas)
8 pages 5 figures
Ultrafast optical excitation of magnons in 2D antiferromagnets via spin torque exerted by photocurrent of excitons: Signatures in charge pumping and THz emission
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-07-04 20:00 EDT
Jalil Varela-Manjarres, Yafei Ren, Branislav K. Nikolic
Recent experiments observing femtosecond laser pulse (fsLP) exciting magnons within two-dimensional (2D) antiferromagnetic (AF) semiconductors – such as CrSBr, NiPS$ _3$ , and MnPS$ _3$ , or their van der Waals heterostructures – suggest exciton-mediation of such an effect. However, its microscopic details remain obscure as resonant coupling of magnons, living in the sub-meV energy range, to excitons, living in \mbox{$ \sim 1$ eV} range, can hardly be operative. Here, we develop a quantum transport theory of this effect, in which time-dependent nonequilibrium Green’s function (TDNEF) for electrons driven by classical vector potential of fsLP are coupled to the Landau-Lifshitz-Gilbert (LLG) equation describing classical dynamics of localized magnetic moments (LMMs) within 2D AF semiconductor. Our TDNEGF+LLG theory explains how fsLP, with central frequency above the semiconductor gap, generates a photocurrent that subsequently exerts spin-transfer torque (STT) onto LMMs as a genuine nonequilibrium spintronic effect. The collective motion of LMMs analyzed by windowed Fast Fourier transform (FFT) reveals frequencies of excited magnons, as well as their lifetime governed by nonlocal damping due to the bath of electrons. In addition, the TDNEGF part of our TDNEGF+LLG self-consistent loop computes a time-dependent density matrix whose off-diagonal elements are utilized to describe, at the mean-field level, inter-orbital Coulomb interaction binding electrons and holes into excitons. Our TDNEGF+LLG theory predicts how excited magnons {\em pump} charge current into the attached electrodes, or locally within AF semiconductor responsible for microwave emission. The windowed FFT of the former signal contains imprints of excited magnons, as well as their interaction with excitons, which could be exploited as a novel probe in future experiments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 5 figures, 109 references; Supplemental Material is available from this https URL
Tailoring the Electronic Properties of Monoclinic (InxAl1-x)2O3 Alloys via Substitutional Donors and Acceptors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Mohamed Abdelilah Fadla, Myrta Grüning, Lorenzo Stella
Ultra-wide bandgap semiconductors such as \b{eta}-Ga2O3 are ideal materials for next-generation power electronic devices. Electronic and mechanical properties of \b{eta}-Ga2O3 can be tuned by alloying with other sesquioxides, notably Al2O3 and In2O3. Moreover, by tuning the In content of a (InxAl1-x)2O3 alloy, its lattice constants can be matched to those of Ga2O3, while preserving a large conduction-band offset. In view of potential applications to \b{eta}-Ga2O3-based heterostructure, we performed atomistic modelling of (InxAl1-x)2O3 alloys using density functional theory to investigate thermodynamic and electrical properties of conventional group IV dopants (Si, Sn, C, Ge), alternative metal donors (Ta, Zr, Hf), and acceptors (Mg, Zn, Cu). The hybrid Heyd-Scuseria-Ernzerhof functional (HSE06) is used to accurately quantify the defect formation energies, ionization levels, and concentrations over a wide range of experimentally relevant conditions for the oxygen chemical potential and temperature. In our atomistic models, Hf and Zr show favourable properties as alternative donors to Si and other group IV impurities, especially under oxygen-poor conditions. Our findings also suggest that acceptors Mg, Zn, and Cu, while they cannot promote p-doping, can be still beneficial for the compensation of unintentionally n-doped materials, e.g., to generate semi-insulating layers and improve rectification.
Materials Science (cond-mat.mtrl-sci)
Prediction of synthesis parameters for N, Si, Ge and Sn diamond vacancy centers using machine learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-07-04 20:00 EDT
Zhi Jiang, Marco Peres, Carlo Bradac, Gil Gonçalves
Diamond and diamond color centers have become prime hardware candidates for solid state-based technologies in quantum information and computing, optics, photonics and (bio)sensing. The synthesis of diamond materials with specific characteristics and the precise control of the hosted color centers is thus essential to meet the demands of advanced applications. Yet, challenges remain in improving the concentration, uniform distribution and quality of these centers. Here we perform a review and meta-analysis of some of the main diamond synthesis methods and their parameters for the synthesis of N-, Si-, Ge- and Sn-vacancy color-centers, including worldwide trends in fabrication techniques and processes. We extract quantitative data from over 60 experimental papers and organize it in a large database (170 data sets and 1692 entries). We then use the database to train two machine learning algorithms to make robust predictions about the fabrication of diamond materials with specific properties from careful combinations of synthesis parameters. We use traditional statistical indicators to benchmark the performance of the algorithms and show that they are powerful and resource-efficient tools for researchers and material scientists working with diamond color centers and their applications.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
31 pages, 15 figures
Helicons in tilted-Weyl semimetals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-07-04 20:00 EDT
Helicons are transverse electromagnetic modes in three-dimensional (3D) electron systems in the presence of a static magnetic field. These modes have been proposed in isotropic or single Weyl semimetals(WSMs) (Francesco M.D. Pellegrino et al, Phys.\ Rev.\ B {\bf 92}, 201407(R) (2015)). In this work, we introduce a tilt term to investigate helicon modes in gapless WSMs within a semiclassical Boltzmann approach and show that the helicon modes exist in tilted WSMs.
Strongly Correlated Electrons (cond-mat.str-el)
Electric Field Induced Superconductivity in Bilayer Octagraphene
New Submission | Superconductivity (cond-mat.supr-con) | 2025-07-04 20:00 EDT
Yitong Yao, Jun Li, Jiacheng Ye, Fan Yang, Dao-Xin Yao
We investigate the energy bands, magnetism, and superconductivity of bilayer octagraphene with A-A stacking under a perpendicular electric field. A tight-binding model is used to analyze the band structure of the system. The doubling of the unit cell results in each band of the single layer splitting into two. We find that applying a perpendicular electric field increases the band splitting. As the electric field strength increases, the nesting of the Fermi Surface(FS) weakens, eventually disrupting the antiferromagnetic order and bilayer octagraphene exhibits superconductivity. Spin fluctuations can induce unconventional superconductivity with s+–wave pairing. Applying a perpendicular electric field to bilayer octagraphene parent weakens the nesting of the FS, ultimately killing the spin-density-wave (SDW) ordered state and transitioning it into the superconducting state, whichworks as a doping effect. We use the random-phase approximation approach to obtain the pairing eigenvalues and pairing symmetries of the perpendicular electric field-tuned bilayer octagraphene in the weak coupling limit. By tuning the strength of the perpendicular electric field, the critical interaction strength for SDW order can be modified, which in turn may promote the emergence of unconventional superconductivity.
Superconductivity (cond-mat.supr-con)
7 pages, 6 figures
Chin. Phys. Lett., 2025, 42(6): 067504