CMP Journal 2026-09-28
Statistics
Nature Nanotechnology: 1
Nature Physics: 1
arXiv: 89
Research Square: 2
Nature Nanotechnology
Mechanical stress remodelling drives epithelial-mesenchymal transition in the tumour microenvironment
Original Paper | Biosensors | 2026-09-27 20:00 EDT
Minji An, Ri Yu, Annie Lin, Jinho Jang, Jiyeon Ohk, Jaemog Jung, Young-Joo Kim, Hosung Jung, Minsuk Kwak, Young-wook Jun, Jinwoo Cheon
The dynamic mechanical response of tissues underlies their physiological function; yet a direct, quantitative measurement of tissue stress in vivo has remained a major challenge. Here we introduce the mechanoMR microparticle sensor, a platform that transduces local tissue mechanical stress into quantitative magnetic resonance read-outs with single-particle resolution. The sensor comprises alginate hydrogel microparticles (~70 μm) homogeneously embedded with Zn0.4Fe2.6O4 magnetic nanoparticles, where stress-induced hydrogel compression reduces local water content and restricts proton diffusion surrounding the magnetic nanoparticles, thereby modulating magnetic-nanoparticle-mediated transverse relaxation (R2). Calibration of the stress-R2 relationship enables a quantitative measurement of local tissue stress over a physiologically relevant range of 0-15 kPa. We demonstrate the platform in tumour spheroids and mouse xenografts, enabling the non-invasive, spatiotemporal mapping of tissue stress during tumour progression. Using this approach, we show that epithelial-mesenchymal transition is accompanied by distinct stress remodelling patterns in vivo. Strikingly, abrupt stress increases, rather than cumulative or peak stress magnitude, determine epithelial-mesenchymal transition induction. Transcriptomic profiling reveals that gradual stress loading activates cytoprotective FOXO/AMPK pathways that reinforce epithelial stability, whereas acute stress surges overwhelm these defence mechanisms, predisposing cells to mesenchymal reprogramming. These findings establish the mechanoMR microparticle sensor as a broadly applicable platform for linking tissue mechanics to cell-state transitions in development and disease.
Biosensors, Nanoparticles
Nature Physics
Hyperbolic wave attractors
Original Paper | Acoustics | 2026-09-27 20:00 EDT
Simon Yves, Enrico M. Renzi, Sander A. Mann, Andrea Alù
Wave behaviour in irregular cavities is typically dominated by chaos, whose diverging trajectories are highly sensitive to initial conditions due to complex internal reflections, and this limits control and stability. Here we show that odd-shaped cavities formed in hyperbolic media suppress chaotic wave dynamics and instead give rise to hyperbolic wave attractors: robust, chiral, broadband and scale-invariant states that organize wave motion analogously to limit cycles in nonlinear dynamical systems. Their defining properties differ from both conventional resonant cavities and chaotic modes. We experimentally demonstrate this phenomenon using elastodynamic waves in a hyperbolic metamaterial and reveal attractor phase transitions, symmetry-driven features and robustness against defects. These results show that wave-attractor physics extends across natural and artificial hyperbolic media and reveal how simultaneous symmetry breaking in the material and cavity geometry produces robust, chiral wave organization in a fully linear system. This work opens possibilities for compact, multifunctional devices in wave-based signal processing and sensing systems by merging functionalities traditionally associated with large, wavelength-scale structures with those of deeply subwavelength cavities.
Acoustics, Optical physics, Phase transitions and critical phenomena
arXiv
Von Neumann’s Two Quantum Entropies
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Von Neumann proposed two quantum entropies, one in 1927 and the other in 1929. He intended to define thermodynamic entropy for quantum states in both cases. The 1927 entropy is the well-known von Neumann entropy, which is zero for all pure states. The 1929 entropy, which is nonzero for almost all pure states, has largely been ignored. After reviewing the history and properties of both entropies, we argue that the 1927 entropy is not thermodynamic entropy and should be used simply as a measure of entanglement, whereas the 1929 entropy is the true thermodynamic entropy for quantum states.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
6pages, 4 figures
The Scale Invariance Behind Boltzmann Counting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Boltzmann counting possesses an exact scale invariance from which the specific entropy emerges without asymptotic approximation. Under thermodynamic replication, this invariance exposes the Gibbs excess at the multinomial level. Its resolution reveals a state-dependent scale structure whose additive refinement generates a continuum reference measure, giving a combinatorial origin to the reference structure of continuous statistical mechanics. The resulting entropy is relative to this measure, and for an ideal gas the scales acquire operational meaning through reversible work.
Statistical Mechanics (cond-mat.stat-mech)
5 pages, 0 figures
Synchronizing Spectral and Interference Criticalities at an Exceptional Point
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Exceptional points (EPs) are spectral singularities, but whether they can be used to control a distinct criticality of coherent interference remains largely unexplored. Here we show in nonlocal superconducting transport how spectral and interference criticalities can be controllably synchronized. In a minimal superconducting double-quantum-dot system, loss imbalance selectively drives one Bogoliubov sector through an EP. The spectral EP and the CAR-ECT interference criticality form distinct structures in control space whose relative ordering can be continuously tuned. At their synchronization point, the interference boundaries between crossed Andreev reflection (CAR) and elastic cotunneling (ECT) coalesce at the EP and bifurcate beyond it, creating a finite CAR-dominated window. The resulting interference window opens with a square-root critical law, whose exponent also governs the finite-temperature observability scale. Detuning unfolds the two criticalities, while retuning restores their intersection, establishing the synchronization as controlled rather than generic. The bifurcation is directly observable in nonlocal conductance. Our results establish exceptional points as spectral control points for independently defined interference criticalities, opening a route to non-Hermitian control of critical quantum interference.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
6+23 pages, 3+4 figures
What Becomes of the Antiferromagnetic String When Long Range Neel Order Is Lost? Exact Results
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Early string descriptions of doped antiferromagnets associate hole motion in a locally Neel ordered background with a path-dependent antiferromagnetic string. We ask what becomes of this mechanism when long range Néel order is lost while short range antiferromagnetic correlations persist. The loss of long range order makes the projective RP^2 description admissible and opens a new topologically nontrivial sector. Its elementary defects are linearly stable half vortices, and a pair of half vortices with opposite windings is logarithmically confined, V(R) = \k{appa} ln (R/r_{core}), \k{appa} = {\pi}\r{ho}_s /2. The resulting confinement is carried not by a one dimensional string but by an extended two dimensional spin texture. Thus, the loss of long range Neel order does not eliminate antiferromagnetic confinement but opens a distinct projective mechanism in which a local path dependent string is replaced, at long wavelengths, by a global topological texture with logarithmic confinement.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Loop content of bond percolation on hyperbolic triangulations: an exact identity and a $1/λ$ expansion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
We study the homology of percolation clusters on disk-shaped patches of the regular $ {3,q}$ triangle tilings for $ q\ge7$ . Varying $ q$ gives a one-parameter family of hyperbolic tilings, from mildly curved ($ q=7$ ) to deeply hyperbolic ($ q=20$ ), and this paper measures and derives loop content as a function of curvature. A single growth-rate parameter $ \lambda(q)$ , the asymptotic ratio of successive ring sizes, governs every result. Total persistent $ H_1$ of the bond-percolation complex, per vertex, is measured across $ q=7,\dots,20$ and found to be a nearly linear function of $ 1/\lambda(q)$ . An exact identity reduces total loop persistence to the weight of the lattice’s minimum spanning tree minus a boundary correction. The boundary correction follows from the ring recursion, and the spanning-tree weight is derived to first order in $ 1/\lambda(q)$ by attaching rings one at a time to a contracted interior, with a correction for loops that close through the ring outside. The resulting formula has no free parameters, gives the large-curvature intercept in closed form as $ 5/4-2\pi/(3\sqrt3)$ , and agrees with the measurements to within the size of the next-order term.
Statistical Mechanics (cond-mat.stat-mech), Probability (math.PR)
12 pages, 3 figures, code at this https URL
Disentangling the Toric Code
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Lei Gioia, Salvatore D. Pace, Ruben Verresen, Shu-Heng Shao, Ryan Thorngren
Commuting-projector Hamiltonians with integer spectrum such as the 1+1d Ising ferromagnet and the 2+1d toric code may be regarded as the generators of non-on-site $ U(1)$ symmetries. In this paper we study whether these symmetries can be made on-site in the presence of finite and infinite-dimensional ancillae. In the finite-dimensional case, we prove that the fractionalized excitations, such as domain walls and anyons, make it impossible to on-site these Hamiltonians. On the other hand, we show that when infinite dimensional ancillae (e.g., rotors) are allowed, both the 1+1d Ising ferromagnet and the 2+1d toric code can be disentangled, yielding on-site symmetries. This is not in contradiction with the non-trivial ground state order of these Hamiltonians, since the ancilla Hamiltonians are no longer bounded from below. Our results indicate agreement between lattice and quantum field theory anomalies in the presence of infinite-dimensional ancillae, while with finite-dimensional ancillae the obstruction to on-siteability may even be non-invertible.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
14+9 pages, 4 figures
Repulsion-Driven $p - i p$ Superconductivity in a Single Valley Revealed by DMRG
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-28 20:00 EDT
Cesar A. Gallegos, Omid Tavakol, Christopher Yang, Steven R. White, Thomas Scaffidi
We demonstrate repulsion-driven topological superconductivity of a single species of Dirac fermions, motivated by valley-polarized phases observed in two-dimensional materials such as rhombohedral graphene. Using density-matrix renormalization group calculations on the Qi-Wu-Zhang lattice model on cylinders of width up to eight, we find a robust phase of spinless chiral $ p$ -wave superconductivity. Pairing already starts at low doping and thus occurs on a small, nearly isotropic Fermi pocket, and is therefore not tied to the particular details or anisotropy of the dispersion but instead seems tied to the non-trivial quantum geometry of the bands. In fact, the winding of the superconductor order parameter is opposite (“$ p-ip$ “) to that of the anomalous Hall metal which forms the parent state, in agreement with expectations recently derived from weak coupling calculations. At larger doping, we find that a pair-density-wave component develops alongside zero-momentum pairing. Our work shows that the combination of strong repulsion, absence of time-reversal in the parent state, and non-trivial quantum geometry form a promising platform to realize topological superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
5 pages main text; 1+3 pages supplemental material
Is the fractional Chern insulator-superconductor transition in twisted MoTe$_2$ direct?
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
The observation of superconducting behaviour near a fractional Chern insulator in twisted MoTe$ _2$ has sparked excitement about a possible direct “anyon superconducting” transition between a topologically ordered and a symmetry-broken phase. We carefully examine the experimentally measured transport data in the relevant region of the low-temperature tMoTe$ _2$ phase diagram and propose a scenario where the nearby reentrant integer quantum Hall effect (RIQHE) acts as an intervening phase between the two. While the RIQHE is most prominent at large displacement fields, we propose that it extends to smaller fields at very low temperatures. Based on this picture, we model the sample as a patchwork of the three phases and show that such a model can explain the main qualitative features of the transport phase diagram, including its dependence on temperature and displacement field. The model predicts that at lower electronic temperatures the apparent FCI-SC transition at zero displacement field should split into two transitions separated by a narrow RIQHE region.
Strongly Correlated Electrons (cond-mat.str-el)
Non-vanishing Density of States in Disordered Weyl Semimetals
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-28 20:00 EDT
There is disagreement in the literature concerning whether the nodal point of a three-dimensional Weyl semimetal survives weak short-range disorder: instanton calculations including fluctuations claim that the zero-energy density of states $ \rho(0)$ vanishes, while exact numerics find a systematically finite number. We settle this disagreement with a full saddle-point calculation, including both instanton and fluctuations. Within the supersymmetric formulation for disorder, the instanton obeys a nonlinear Weyl equation whose solution is an exact $ j=1/2$ hedgehog whose full functional form we numerically compute. We then compute the fluctuations about this saddle point, carefully identifying all zero modes, and computing the reduced superdeterminant as a convergent Fredholm determinant. No fermionic zero mode beyond a Kramers doublet exists, and at finite disorder $ w$ , the fluctuations become a finite one-loop prefactor, $ \rho(0)=\mathcal{A} w^{-4} \exp(-s^\ast/w^2)(1+O(w^2))$ , in normalized units with $ s^\ast = 6.4163(2)$ and $ \mathcal{A} = 27.47(8)$ for Gaussian-correlated disorder. This expression matches exact numerics on a single Weyl cone over four orders of magnitude with no fitted parameters (the amplitude is $ \times 0.76$ the one-loop value), establishing that the density of states is finite for any disorder strength.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 5 figures, 2 tables
Anyonic molecules through the trion looking glass
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Hao-Ran Cui, Vladimir Calvera, Umang Mehta, Hart Goldman
Motivated by recent optical measurements in twisted MoTe$ _2$ homobilayers, we numerically study the binding of itinerant anyons to ordinary electronic bound states. Using a minimal few-body model of an anyon alongside holes and electrons in a Gaussian trapping potential, we show that a fractionally charged bound state comprised of an anyon and an ordinary electronic trion can become favorable nearby local electrostatic defects. The resulting object is an anyonic molecule wherein the anyon is bound to the trion ``nucleus,’’ which in turn is localized to the defect and can be excited optically. We find that the resulting anyon-trion can exhibit a photoluminescence red-shift relative to the ordinary trapped trion, with binding on the meV scale for parameters relevant to twisted MoTe$ _2$ . We find that the value of this red-shift depends on $ \textit{both}$ the anyon’s fractional charge and its kinetic energy, thereby encoding both universal and non-universal anyon properties. Our results are qualitatively consistent with observations in twisted MoTe$ _2$ .
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
7+8 pages,10 figures
Cooper pair charge Kondo effect in a hybrid quantum dot - superconductor device
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Luca Gonfiantini, Lorenzo Maffi, Michele Burrello
We consider a tunable hybrid device composed of four quantum dots and a floating superconducting island – the so-called poor man’s tetron – close to its effective particle-hole symmetric point and coupled to four external leads. We predict the onset of a charge Kondo effect mediated by Cooper pairs, resulting from the strong crossed Andreev reflections that dominate its low-energy behavior. This two-channel Kondo effect makes the poor man’s tetron behave as a double Cooper pair splitter, turning uncorrelated incoming electrons into spatially separated Cooper pairs. Based on renormalization group techniques, we analyze both its weak and strong coupling regimes and we determine its non-Fermi liquid signatures. Our estimates indicate that the fractional conductance and transport features associated to this two-channel charge Kondo effect can be observed over a broad range of temperatures and anisotropies in realistic experimental conditions.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
24 pages, 8 figures
Current density functional theory in the age of generalized Kohn-Sham theories
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
I review the evolution of electronic non-relativistic current density functional theory (CDFT) from its original formulation in the late 1980’s to present day’s formulations, which rely on the generalized Kohn-Sham theory. Axel Becke’s outstanding contributions are highlighted throughout. I propose a form of the generalized Kohn-Sham equation that combines the exchange-correlation vector potential of the original formulation with an ``effective mass term” – the latter following from the inclusion of Becke’s kinetic energy density as a basic input of the exchange-correlation energy functional.
Materials Science (cond-mat.mtrl-sci)
16 pages, no figures
Unified description of random motions and generalized Fokker-Planck equations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
This review surveys diverse types of random motion within a unified framework, introducing essential mathematical tools, including special functions and fractional calculus, in a pedagogical manner. We focus on generalized random motions in one-dimensional space described by Fokker-Planck like equations, whose fundamental solutions take a universal and simple form in the Laplace-Fourier domain in terms of a generic function $ \varphi(s)$ . By exploring the functional forms of $ \varphi(s)$ consistent with physical constraints, we derive a broad class of stochastic dynamics. This includes Brownian and active motion, simple and anomalous diffusion, and processes featuring stochastic resetting or trapping mechanisms. For each case, we provide the corresponding kinetic equation, explicit solutions (where available), and mean-square displacements alongside their asymptotic behaviors. Finally, we discuss the physical interpretation of these motions through the lens of time-changed processes and subordinators.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
36 pages
Engineering nonlinear spin-orbit torque driven by intra-band transport in MoSe$_2$/CrI$_3$ and WSe$_2$/CrI$_3$ van der Waals heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Leyla Majidi, Azadeh Faridi, Reza Asgari
The role of nonlinear carrier dynamics in current-driven spin phenomena remains poorly understood in van der Waals magnetic heterostructures. Here, we investigate the spin polarization and the resulting spin-orbit torque (SOT) in transition-metal dichalcogenide/chromium iodide (TMDC/CrI$ _3$ ) heterostructures, focusing on WSe$ _2$ /CrI$ _3$ and MoSe$ _2$ /CrI$ _3$ , in the zero-Rashba spin-orbit coupling (SOC) limit and beyond the linear-response regime. We find that linear spin polarization is forbidden by symmetry, making nonlinear intraband transitions the dominant mechanism in this regime. Consequently, the current-driven spin response differs fundamentally from conventional linear-response predictions. The resulting nonlinear spin polarization generates a purely field-like torque whose magnitude and sign depend sensitively on the chemical potential and doping type, with pronounced asymmetries between n- and p-doped systems. A strong material dependence is also observed: n-doped MoSe$ _2$ /CrI$ _3$ exhibits a torque nearly an order of magnitude larger than that of WSe$ _2$ /CrI$ _3$ , together with two sign reversals, reflecting differences in their SOC and proximity-exchange parameters. Structural and electrostatic control through the twist angle and gate electric field provides additional means of tuning the nonlinear torque, including substantial modulation and controllable sign reversals. These findings establish TMDC/CrI$ _3$ bilayers as a versatile platform for engineering nonlinear spin-orbit phenomena in ultrathin, low-power spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11pages,9 figures
Activating Basal Planes in Transition Metal Dichalcogenides for CO2 Reduction to CO through Alloying
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Eric Montufar-Morales, Daniel Rinder, Pravan Omprakash, Rohan Mishra, Gwan Yeong Jung
Transition metal dichalcogenides (TMDCs) have emerged as highly tunable platforms for electrocatalysis, particularly for the CO2 reduction reaction (CO2RR). While TMDC edge sites exhibit catalytic activity, the basal plane is typically inert, severely limiting the overall active site density. In this work, we show that sulfur vacancies activate the basal plane of 1H-TMDCs, while concurrent solid-solution alloying provides a mechanism to broadly tune intermediate adsorption energies. We evaluate a library of quasi-binary TMDC sulfide alloys comprising V, Nb, Ta, Mo, and W, screening them by stability, defect energetics, and competitive selectivity to identify the most effective catalysts for CO2RR. Electronic-structure analysis reveals that a d-band center closer to the Fermi energy weakens intermediate binding by leaving key bonding states unoccupied above the Fermi energy. Our calculations identify (Nb,Ta)S2 as a promising catalyst with low sulfur vacancy formation energies, near-optimal CO2RR intermediate binding, and selectivity against the hydrogen evolution reaction. Overall, this work establishes a rational design framework for TMDC alloy catalysts through the simultaneous use of defect engineering and alloying.
Materials Science (cond-mat.mtrl-sci)
Critical escape dynamics of an active particle moving on curved surfaces
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Maxim Root, Hartmut Löwen, Peter Sollich, Lorenzo Caprini, Alexander P. Antonov
On the macroscopic scale, active (self-propelled) objects moving through complex environments are often subject to effects arising from both the curvature of the surrounding surface and external influences such as gravity. We study the Kramers escape problem for active Brownian particles in two settings: motion in an external potential driven solely by gradient forces, and motion on a curved manifold subject to an additional constant gravitational force. In the absence of translational noise, a sharp dynamical transition occurs when the self-propulsion velocity $ v_0$ reaches a critical velocity $ v_c$ required for an escape. Above this threshold, the escape rate $ k$ follows a universal scaling form, $ k \propto \exp\left[-\mathrm{const}(v_0-v_c)^{-\gamma}\right]$ , with an exponent $ \gamma=3/2$ for the escape in a potential and $ \gamma=1/2$ for the escape on a curved manifold in the presence of gravity. These distinct exponents reveal how the interplay of activity, surface curvature, and gravity determines the critical escape dynamics. Our theoretical predictions are verified by numerical simulations.
Statistical Mechanics (cond-mat.stat-mech)
9 pages, 5 figures
Hydrogen-stabilized multimodal high-index twin network in iron
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Mehrab Lotfpour, Haoran Cui, Yan Wang, Eduardo Vitral, Lei Cao
Hydrogen significantly affects plasticity in bcc iron, but its role is commonly attributed to dislocation-mediated mechanisms, leaving the influence of hydrogen on phase transformation and deformation twinning poorly understood. We use a density-functional-theory-trained deep-neural-network interatomic potential and large-scale molecular dynamics to study pure bcc Fe and Fe containing 10% hydrogen. It is found that hydrogen lowers the yield stress but, more importantly, increases the persistence of {112} twin variants and suppresses detwinning. This effect stabilizes an interconnected {332}-{10 9 3} multimodal twin network and produces pronounced post-yield hardening. Higher temperature promotes the initial transformation but weakens the persistence of the high-index multimodal twin network. Moreover, twinning follows distinct loading-dependent pathways: compression generates {332} and {10 9 3} boundaries through co-zone and non-co-zone twin-twin interactions, whereas tension produces {7 4 1} boundaries through non-co-zone interactions. These results establish a pathway-based picture in which the intermediate phase determines the accessible twin modes and variant crystallography, while hydrogen and temperature control their kinetic survival and the emergence of high-index twin networks.
Materials Science (cond-mat.mtrl-sci)
33 pages, 8 figures, 1 table. Submitted to the International Journal of Plasticity
Revealing Polar Walls in CsPbBr3: Herringbone Structure and Formation Pathway
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Weilun Li, Qimu Yuan, Michael B. Johnston, Joanne Etheridge
Domain walls in ferroic materials can host nanoscale functionalities absent from the periodic crystal, offering new opportunities to control electronic transport and polarization in semiconductor devices. Metal halide perovskites demonstrate important photophysical properties; however, their ferroic properties remain unclear. Here we discover a hierarchical herringbone network of polar walls within the non-polar halide perovskite CsPbBr3 comprising ferroelastic twin walls and antiphase walls. Atomic-scale imaging reveals that both wall types comprise nanoscale regions whose inversion-symmetry is broken compared to the surrounding bulk lattice. In-situ heating experiments show that these interfaces form sequentially during symmetry-lowering phase transitions, revealing a different formation pathway compared with ‘conventional’ oxide perovskites. These polar nano-walls, together with their enclosed topology, may impact carrier transport. This reveals a previously unrecognized structural motif in CsPbBr3, providing new insights into their photophysical and optoelectronic behavior.
Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures
Anomalous Pressure-Enhanced Polarization in Sliding Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Lujin Min, Sahas Kamat, Ameer Mustafa, Nguyen The Duy, Kyle Nadel, Junhao Lin, Kenji Watanabe, Takashi Taniguchi, Daniel Bennett, Brad J. Ramshaw, Kenji Yasuda
Hydrostatic pressure commonly suppresses polarization in conventional displacive ferroelectrics by weakening the off-center ionic distortion. Sliding ferroelectrics may provide a contrasting case because their polarization arises from stacking-dependent interlayer charge transfer rather than intra-unit-cell ionic displacement. Here, hydrostatic pressure is shown to enhance, rather than suppress, the polarization of parallel-stacked bilayer boron nitride, a prototypical sliding ferroelectric. A graphene layer placed on top of a ferroelectric boron nitride bilayer is used for sensing the evolution of polarization under pressure. The pressure enhances both the interlayer potential and the ferroelectric polarization, with the latter increasing approximately linearly by 80% up to 1.66GPa. These results establish hydrostatic compression as a tuning parameter for sliding-ferroelectric polarization, with potential implications for ultrathin slidetronic memory devices.
Materials Science (cond-mat.mtrl-sci)
Nuclear spin-lattice relaxation rate near a two-dimensional antiferromagnetic quantum critical point
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
We study the effects of zero-point spin fluctuations on the nuclear spin-lattice relaxation rate 1/$ T_1$ around a two-dimensional antiferromagnetic quantum critical point in the self-consistent renormalization theory. For a weak mode-mode coupling constant $ y_1 < $ 0.1, the finite temperature behavior of 1/$ T_1$ across the quantum critical point resembles that for only the thermal spin fluctuations. For a strong mode-mode coupling constant $ y_1 > $ 0.1, 1/$ T_1$ takes its local maximum as a function of temperature in the nearly antiferromagnetic state. Experimental observation of the local maximum in the $ ^{63}$ Cu nuclear spin-lattice relaxation rate 1/$ T_1$ of lightly-doped superconductors La$ _{2-x}$ Sr$ _x$ CuO$ _4$ with $ x$ = 0.06-0.10 is associated with the effects of the zero-point spin fluctuations. The two-dimensional magnetic quantum critical point and the role of the zero-point spin fluctuations are discussed in the electron spin dynamics of underdoped superconductors La$ _{2-x}$ Sr$ _x$ CuO$ _4$ .
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
6 pages, 5 figures
Shear stress during self-assembly encodes stiffness of network-based materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
Lens M. Dedroog, Olivier Deschaume, Carmen Bartic, Yovan de Coene, Erin Koos, Minne P. Lettinga, Mehdi Bouzid
The mechanical properties of network-based materials have been extensively studied under qui- escent conditions, yet their self-assembly in nature occurs mainly in a mechanically stressed envi- ronment. Here, we show that the stiffness of collagen networks, one of the main building blocks of the mammalian extracellular matrix, can be tuned by applying shear stress during gelation, which first strains and aligns the material, then triggers a dramatic irreversible increase in the elastic modulus. This stiffening is anchored by maintaining the stress until the gel is fully matured. Using particle-based simulations, we show that the underlying microscopic mechanism is likely generic to a broad class of network-based systems and arises from two synergetic effects: changes in the network orientation and topology through the formation of permanent contacts that stabilize the system. Our findings are rationalized using a rigidity percolation framework and offer a general principle for encoding elasticity in biological and synthetic networks.
Soft Condensed Matter (cond-mat.soft)
Material and thermal properties of MgCl2 molten salt by ab initio and machine-learning molecular-dynamics simulations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
Roberto Llovera, María Andrea Barral, Verónica Vildosola, Florencia Cantargi, Claudio Pastorino
We study the structural, thermophysical and dynamical properties of molten MgCl2 over a wide temperature range using Ab Initio Molecular Dynamics (AIMD) and molecular dynamics simulations based on machine-learning interaction potentials (MLIPs). MLIPs can achieve near-AIMD accuracy at a fraction of the computational cost, enabling simulations of larger systems and longer timescales. This opens up the possibility of studying the system under out-of-equilibrium conditions, which in turn allows for the calculation of physical properties, such as the thermal conductivity or viscosity, that cannot be obtained reliably for the typical time and length scales accessible to AIMD. We follow two complementary approaches to develop and evaluate the MLIPs. Firstly, we develop a Deep Potential (DP) from scratch using AIMD trajectories at different temperatures. Secondly, we also evaluate two out-of-the-box foundation models and a fine-tuned version of one of them. The fine-tuning is performed using configurations from the AIMD trajectories originally used to train the Deep Potential. We compare the predictions of the trained DP, the foundation models and AIMD simulations with the available experimental data and provide a comprehensive calculation of the most important physical quantities of molten MgCl2. We compute densities, radial and angular distribution functions, thermal conductivity, heat capacity, viscosity and diffusion coefficients over the 1000-1600 K temperature range. This range is relevant to important technological applications such as thermal energy storage, generation IV nuclear reactors and concentrated solar power systems. Finally, we briefly review the accuracy and performance of the different MLIPs versions used throughout the work.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
18 pages, 12 figures
Superconductivity in Noncentrosymmetric NbReSi: Beyond Harmonic and Adiabatic Limits
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-28 20:00 EDT
Shashi B. Mishra, Sohair ElMeligy, Pratibha Dev
The noncentrosymmetric superconductor NbReSi (Tc=6.5 K) is being actively explored for unconventional pairing that is allowed by its broken inversion symmetry. Despite broad experimental interest, what drives its superconductivity remains an open question. We show that the electronic states at the Fermi level are dominated by Nb and Re $ d$ -states. Vibrations of the same heavy-metal framework contribute more than 95% of the electron-phonon coupling, with the strongest coupling arising from the sublattice-selective breathing mode involving strongly bonded Re atoms. Harmonic Migdal-Eliashberg theory overestimates Tc by more than 60%. The zero-point anharmonic hardening of these modes reduces the coupling by 20%. The leading vertex correction becomes important as well despite low phonon energies due to the contribution of spatially localized Re-d orbitals to the electronic band structure near the Fermi level. Together, anharmonicity and vertex corrections bring the calculated Tc and superconducting gap into close agreement with experiment, establishing NbReSi as a moderately coupled, phonon-mediated superconductor whose quantitative description requires going beyond harmonic Migdal–Eliashberg theory.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
6pages, 8 figures, and includes 7pages of supplementary information
Dual Topological Channels in a Programmable Mechanical Metamaterial
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Topological mechanical metamaterials generally derive their robustness from one of two distinct mechanisms: kinematic topology, which localizes zero-frequency floppy modes through geometric compatibility, or band topology, which localizes finite-frequency waves through topological bandgaps. Because these mechanisms arise from fundamentally different physical principles, mechanical systems are typically engineered to exploit either static or dynamic topological functionality, but not both simultaneously. Here we demonstrate that a single mechanical metamaterial can host two independent topological channels governing static and dynamic response within the same architecture. Using a generalized rotor-chain lattice with two coupled rotational degrees of freedom per unit cell, we realize the coexistence of a topological polarization mode and a finite-frequency topological band mode. We show that the two channels are governed by distinct invariants and can be programmed independently through geometry, angular asymmetry, and stiffness dimerization. Remarkably, despite being governed by distinct topological invariants and controlling different physical responses, the two channels undergo topological transitions at a common symmetry-controlled critical geometry. Experimental measurements using scanning laser Doppler vibrometry confirm simultaneous localization of a boundary floppy mode and a finite-frequency domain-wall state in the same structure. These results establish dual topological channels as a general design principle for multifunctional mechanical metamaterials and demonstrate how static deformation and dynamic wave transport can be programmed independently within a single architecture.
Materials Science (cond-mat.mtrl-sci)
Emergent Wigner magnon crystals in a fully frustrated Heisenberg four-leg tube
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Azam Zoshki, Hamid Arian Zad, Jozef Strecka
The ground state, magnetization curves, low-temperature thermodynamics, and heat-engine performance of the fully frustrated spin-$ 1/2$ Heisenberg four-leg tube with antiferromagnetic inter- and intra-plaquette coupling constants J1 and J2 are examined using exact diagonalization, density matrix renormalization group, and localized-magnon theory. In the unfrustrated to weakly frustrated regime J2/J1 << 2, the system exhibits a continuous field-driven quantum phase transition between the gapped Haldane phase and a gapless Tomonaga-Luttinger quantum spin liquid. In the highly frustrated regime J2/J1 > 2, the system contrarily displays discontinuous field-driven quantum phase transitions between the Wigner magnon crystals, which are manifested in zero-temperature magnetization curves as intermediate plateaus at zero, one-quarter, one-half, and three-quarters of the saturation magnetization. The low-temperature magnetic and thermodynamic properties in this regime are accurately captured by an effective interacting lattice-gas model of two monomer quasi-particle species constructed from localized one- and two-magnon states. Finally, we explore a quantum Stirling heat engine using the fully frustrated four-leg tube as the working medium. The work output and efficiency are strongly suppressed near discontinuous field-induced transitions and reach pronounced local maxima well inside the stability regions of the Wigner magnon crystals.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
14 pages, 8 figures
Assessing the Transferability of General-Purpose MachineLearning Interatomic Potentials for Heterogeneous Catalysis with HetCat26
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Alexandre Peuch, Giaan Kler-Young, Kaifeng Niu, Jinwoo Hwang, Manos Mavrikakis, Angelos Michaelides, Fabian Berger
Foundation machine learning interatomic potentials (MLIPs) promise near-density functional theory (DFT) accuracy across broad areas of chemistry and materials science. However, their performance in describing systems and processes relevant to heterogeneous catalysis remains underexplored. Here, we introduce HetCat26, a collection of benchmark tests designed to assess pre-trained MLIPs across key aspects of catalytic modeling, including surface energetics, metal-metal oxide interactions, adsorption, and catalytic reaction networks. Evaluating fifteen foundation models, we find that performance on existing general materials benchmarks is only weakly predictive of performance on HetCat26; transferability to heterogeneous catalysis cannot be inferred from these general benchmarks. Across the benchmark tests, current models describe surface energetics and, perhaps surprisingly, reaction barriers well, whereas larger errors are observed for adsorption, and DFT site preferences are often not reproduced. Two models, eSEN-30M-OAM and MACE-MH-1-OMAT, nevertheless achieve high accuracy across the properties evaluated. Beyond model benchmarking, HetCat26 highlights the importance of training data consistency: PBE and PBE+U calculations should not be mixed within a training set. Overall, we identify challenges limiting the transferability of current foundation MLIPs to heterogeneous catalysis and, more broadly, to chemical reactions at interfaces, providing guidance for the development of the next generation of foundation models.
Materials Science (cond-mat.mtrl-sci)
Realignment of ferroelectric nematic by photoinduced electric field
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
Sathyanarayana Paladugu, Oleksandr Kurochkin, Ruslan Kravchuk, Mykola Kravets, Volodymyr Sashuk, Bijaya Basnet Vassili G. Nazarenko, Sergij V. Shiyanovskii, Oleg D. Lavrentovich
Liquid crystal displays (LCDs) employ thin pixels of a paraelectric nematic, confined between two glass plates with transparent indium tin oxide (ITO) electrodes. A voltage applied to the electrodes realigns the molecules, changing the optical appearance of the pixel. Here we demonstrate that a similar molecular realignment can be triggered by low-power light irradiation when the paraelectric nematic in the cell with ITO electrodes is replaced with a ferroelectric nematic (NF). Irradiation creates an intrinsic electric field that is strong enough to realign the NF but too weak to affect the paraelectric nematic. The extraordinary sensitivity of the ITO/NF pair to light irradiation creates a platform for optical control of ferroelectric polarization and applications in photonics, sensing, smart windows, and beyond.
Soft Condensed Matter (cond-mat.soft)
23 pages, 4 figures
Electrochemical Growth of Full Volume Meissner Effect Superconducting BKBO
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-28 20:00 EDT
Oleksandr Foyevtsov, Kateryna Foyevtsova, Mohamed Oudah, Dan Bizzotto, George Sawatzky
In this work we show the results of electrochemical synthesis of BKBO crystals using three different experimental setup configurations. The setups differ between each other by varying level of control over physical variables and progressing from a two-electrode to a three-electrode configuration using highly oriented platinum counter electrode. By systematic analysis of the temperature dependence of the magnetic susceptibility at the superconducting transition of the collected crystals we observe that an order of magnitude sharper superconducting transition is achieved for the most comprehensive three-electrode setup. In addition, the level of chemical substitution can be controlled by the value of the overpotential versus reference electrode. We demonstrate that with this technique a full volume Meissner effect can be achieved with a sharp transition temperature for the superconducting crystal.
Superconductivity (cond-mat.supr-con)
18 pages 6 figures
Strain-controlled topology and quantum control at a cubic Ce$^{3+}$ crystal-field crossing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Field-tuned crystal-field crossings provide a route to synthetic topology in localized rare-earth degrees of freedom when symmetry-resolved perturbations can independently control the crossing states. Here we show that a field-induced crossing in cubic Ce$ ^{3+}$ has precisely this structure. For $ B\parallel[001]$ , the crossing is protected by a twofold rotation, while the $ T_{2g}$ shears $ \epsilon_{xz}$ and $ \epsilon_{yz}$ break that protection and mix the two states through orthogonal pseudospin components. Together with magnetic-field detuning, these controls generate an isolated diabolical point with unit-magnitude Chern charge in a three-dimensional parameter space. Using the CeTe crystal-field scale gives an ideal single-ion crossing near $ 35.5$ T. A calibrated point-charge calculation gives a representative projected shear coupling $ |\alpha_{T_{2g}}|\simeq18.1$ meV per unit tensor strain, corresponding to gaps of $ 0.036$ and $ 0.072$ meV for tensor shears of $ 0.10%$ and $ 0.20%$ . We identify the associated elastic and magnetic signatures, discuss the limitations of the electrostatic estimate in a hybridizing Ce compound, and determine the adiabatic and coherence requirements for cyclic geometric control. The result is a symmetry-based framework that connects high-field crystal-field reconstruction, strain response, and parameter-space topology in rare-earth systems.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
11 Pages, 6 Figures
A hydrogen-informed Rice-Beltz model for crack-tip dislocation emission under mixed-mode loading
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
The fundamental competition between crack-tip cleavage and dislocation emission dictates the ductile-to-brittle transition in crystalline solids. In hydrogen-charged environments, this delicate balance is disrupted, yet existing models often struggle to self-consistently capture the atomic-scale thermomechanical modulation of the emission barrier. Here, we propose the hydrogen-informed Rice-Beltz framework to quantify the critical stress intensity factors (SIFs) required for initial dislocation nucleation under mixed-mode (I+II) loading. By integrating the elastic interaction of the dilatational field of interstitial hydrogen and the applied stress fields against the incipient dislocation core, the model recovers the non-monotonic relation between the most probable SIF and the hydrogen concentration. Unlike the classical pure mode-I (or mode-II) scenario, the minimization of the local strain energy density is employed to generate closed-form nominal driving forces, which are subsequently embedded into a transition-state-theory framework. This atomistically-informed approach yields the most probable SIF for the first dislocation emission event as a function of the loading rate, slip angle, and hydrogen concentration, providing a rigorous, parameter-free boundary condition for the onset of hydrogen-modulated crack-tip plasticity.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
K. Zhao Mechanics of Materials 223 (2026) 105876
Observation of the electronic Pomeranchuk effect in generalized Wigner crystals of twisted MoS$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Xinjie Fang, Linfeng Wu, Naitian Liu, Le Zhang, Wenqiang Zhou, Jing Ding, Zhangyuan Chen, Hanxiao Xiang, Yue Xiao, Kenji Watanabe, Takashi Taniguchi, Shuigang Xu
Moire superlattices in transition metal dichalcogenides provide a highly tunable platform for exploring strongly correlated electronic phases, such as generalized Wigner crystals. While these crystalline states typically melt with increasing thermal fluctuations, an electronic analogue of the Pomeranchuk effect can stabilize the localized solid phase at elevated temperature through isospin entropy. Here, we report the observation of an electronic Pomeranchuk effect at the fractional filling factors of $ \nu = 1/3$ and $ \nu = 1/4$ in AB-stacked twisted bilayer MoS$ _2$ with twist angles of 4.1$ ^\circ$ and 3.9$ ^\circ$ , respectively. At ultra-low temperature, the system exhibits a highly conducting, itinerant behavior at these fractional fillings, characteristic of a compressible Fermi-liquid ground state. Upon heating, the system exhibits a counterintuitive increase in the longitudinal resistivity, signaling an isospin-entropy-driven transition into a localized generalized Wigner crystal state. Our findings highlight the unique capacity of flat bands in twisted bilayer MoS$ _2$ for stabilizing highly degenerate magnetic configurations, offering new insights into the thermodynamic phase diagrams of low-dimensional correlated systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Topological Superconducting Phases in a Strained Altermagnet-Superconductor Heterostructure
New Submission | Superconductivity (cond-mat.supr-con) | 2026-09-28 20:00 EDT
Keita Yoshizawa, Ryo Okugawa, Takami Tohyama
We investigate topological superconductivity in a heterostructure consisting of a two-dimensional $ s$ -wave superconductor and a $ d$ -wave altermagnet with Rashba spin-orbit coupling. In particular, we study the effects of strain and hopping anisotropy on the topological superconducting phases. By calculating the Chern number, we obtain topological phase diagrams as functions of the chemical potential and the strength of the effective magnetic field induced by the magnetic proximity effect. We find that strain-induced lattice distortion allows topological superconducting phases to emerge over a broad parameter region. Our findings suggest that strain that lowers symmetry can serve as a route to realizing topological superconductivity in altermagnet-superconductor heterostructures.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures
Front-based construction of quantum droplets, bubbles, and hole states in a Bose mixture
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-28 20:00 EDT
Sherzod R. Otajonov, Fatkhulla Kh. Abdullaev
We study nonlinear holes, bubbles, kink fronts, and quantum-droplet-like states in an elongated Bose mixture governed by an extended Gross-Pitaevskii equation with attractive cubic mean-field interactions and repulsive quartic Lee-Huang-Yang contribution. We classify the constant-amplitude backgrounds: the Bogoliubov-de Gennes spectrum shows that the upper branch is modulationally stable, whereas the lower branch is unstable to long-wavelength perturbations. Grand-potential and pressure determine the vacuum-finite-density coexistence point and the unique background supporting stationary kink and antikink fronts. Symmetric holes on the stable background have a density deficit and integral width that diverge near coexistence as the hole separates into two nonlinear fronts. A multiplicative kink-antikink construction connects bell-shaped states to broad flat-top droplets and approaches the stationary quantum-droplet family as the front separation increases. An antikink-kink sum with equal signs generates bubble-like density depletions without a phase jump, whereas their difference produces dark-hole-like profiles with a $ \pi$ phase difference between the asymptotic backgrounds. Bubble depth increases with front separation, distinguishing gray-like and dark-like profiles. Real-time simulations show that deep bubbles persist under weak random perturbations, demonstrating finite-time robustness without establishing spectral stability. In the asymmetric two-component model, localized relative-density modes can induce spinor-driven breakup on a modulationally stable background, while robust holes persist near the kink limit. Collisions of kink-antikink droplet-like states display phase-dependent merging, asymmetric particle transfer, and effective reflection. These results connect nonlinear fronts with bubbles, phase-jump holes, and self-bound droplets in beyond-mean-field Bose mixtures.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
19 pages, 13 figures
The conductance filtration: sink-relative persistence and exact edge sensitivity for heat transport in particle-filled composites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Daisuke Yasufuku (U-MAP Co., Ltd.)
We formulate the thermal conductance $ g_e$ of a particle pair as three branch types – contact, near-contact and bond – within a single construction, and we introduce the filtration that takes this $ g_e$ as its axis (the conductance filtration) together with persistence taken relative to the sink boundary. We then show that the dissipation share is exactly the logarithmic sensitivity of the effective conductance, and that a finite change of a single edge is predicted exactly in closed form. The allocation of the dissipation among branch types, and the idealisation ratio of each mechanism (interface, matrix and particle), are thereby obtained as diagnostic quantities on one and the same graph representation.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Engineering, Finance, and Science (cs.CE)
45 pages, 15 figures. Japanese-language version: this https URL
Engineering Ferromagnetism in Wide Bandgap w-AlN for Spintronic Applications: Insights from DFT Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Spintronics drives the search for functional materials, pursuing room-temperature dilute magnetic semiconductors to realize practical, energy-efficient devices. This paper presents a theoretical investigation into the magnetic properties of w-AlN doped with Cr, Ru, and Rh atoms, using spin-polarized density functional theory calculations with supercell models. Calculations of point-defect formation energies as a function of the Fermi level predict that Cr4+, Ru4+, and Rh3+ are the most favorable charge states substituting Al in w-AlN. With these preferred charge states, Cr-doped AlN is stable in the ferromagnetic state, preferable for spintronic devices, across a wide concentration range (1.85 to 16.67% of Al). Conversely, Ru- and Rh-doped AlN are unstable in the ferromagnetic state relative to the antiferromagnetic state. Further investigation into the electronic density of states reveals a fascinating evolution: for Cr concentrations below 5.56%, the Fermi level resides within the band gap directly above the valence band maximum, keeping the system insulating. It transitions to a high-spin half-metallic state between 7.40% and 12.96%, and finally transforms into a normal metal at 16.67% Cr. This behavior is absent in the DOS of the antiferromagnetic model of Ru- and Rh-doped systems, where insulating and metallic behaviors instead appear non-sequentially with varying concentrations.
Materials Science (cond-mat.mtrl-sci)
16 pages, 14 figures, Revised and Expanded Version of the Previous Account
When Is Molecular-Dynamics-Predicted Ionic Conductivity Reliable in Solid Electrolytes?
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Yiwei You, Shaofei Chen, Zhifeng Wu, Pushun Lu, Eric Jianfeng Cheng, Songyan Chen, Shunqing Wu
Molecular dynamics is widely used to predict ionic conductivity in solid electrolytes, but the reliability of these predictions is often difficult to assess. Our analysis identifies finite trajectory length, limited cell size, and insufficient sampling as intrinsic limitations of finite atomistic ion-transport calculations. Cubic Li7La3Zr2O12 is used as a representative solid electrolyte to quantify their consequences. These limitations can remain hidden behind apparently linear mean-squared displacements and well-behaved Arrhenius relations, leading to inaccurate diffusivities, activation energies, and extrapolated ionic conductivities. Such inaccuracies can misrank candidate solid electrolytes and consequently misdirect computational screening and experimental validation. Here, we establish the local mean-squared-displacement exponent, {\alpha}(t), as a quantitative reliability criterion that links dynamical convergence to errors in diffusivity and Nernst-Einstein ionic conductivity. The criterion further determines the minimum trajectory length required to achieve a prescribed accuracy as a function of temperature. Independent replicas reduce statistical uncertainty, while selective single-axis expansion mitigates finite-size effects. By establishing when simulated ionic conductivity is quantitatively trustworthy, this approach enables more reliable materials ranking and more efficient use of computational and experimental resources, thereby accelerating the development of high-performance solid electrolytes for solid-state batteries.
Materials Science (cond-mat.mtrl-sci)
14 pages, 5 figures
Energetically Driven Structure Matching for Autonomous Total X-ray Scattering Experiments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Emil J. P. Frost, Martin A. Karlsen, Jonas H. Jensen, Rodrigo Moreno, Jørn Lambertsen, Jonathan Quinson, Andy S. Anker, Alexander Bagger, Tejs Vegge
The emergence of autonomous laboratories motivates rapid conversion of experimental data into reliable atomistic models on time-scales compatible with closed-loop optimization. Here we develop an energetically driven structure matching framework for analysis during ongoing total X-ray scattering experiments. Using data from gold nanoparticles, we match against idealized spherical, octahedral, decahedral, and icosahedral geometries, their machine-learned interatomic potential (MLIP)-relaxed structures, and molecular dynamics (MD) ensembles. Idealized models are fast to generate but can misassign morphology and systematically underestimate size by neglecting surface relaxation, strain, and thermal disorder. MLIP relaxation markedly improves both, while MD ensemble averaging agrees best with experiment. We therefore introduce a hierarchical workflow combining rapid idealized screening with targeted MLIP and MD refinement of top candidates, delivering improved structural feedback without interrupting autonomous operation. This framework provides a route towards autonomous campaigns in which the target structure itself can be updated in response to the evolving energy landscape of structures compatible with the experimental data.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
Rare-earth Bilayer Triangular Lattice as a Platform for Tunable Ground States and Field-induced Magnetic Phases
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Jianqiao Wang, Fangli Li, Yangyang Yu, Quan Xiao, Zhibin Qiu, Liusuo Wu, Shu Guo
Rare-earth bilayer triangular lattice (TL) antiferromagnets provide a versatile platform for realizing diverse magnetic states by combining geometric frustration, interlayer coupling, and strong single-ion anisotropy. Here, we report a family of R2O2Se (R = Sm, Eu, Tb-Lu; ROSe) single crystals featuring bilayer equilateral TLs. Magnetic susceptibility and specific-heat measurements reveal predominantly antiferromagnetic (AFM) interactions and diverse magnetic ground states across the series, including successive AFM transitions in TbOSe and single AFM transitions in SmOSe, DyOSe, HoOSe, and YbOSe. Notably, DyOSe and HoOSe exhibit pronounced 1/2 magnetization plateau-like features for fields along the c-axis, revealing field-induced magnetic states. In HoOSe, complementary thermodynamic and magnetization measurements resolve three critical fields and a rich field-temperature phase diagram containing five distinct magnetic phases. These results establish rare-earth bilayer TLs as a chemically tunable materials platform for accessing novel quantum spin states through the interplay of lattice geometry, single-ion anisotropy, and competing magnetic interactions.
Materials Science (cond-mat.mtrl-sci)
40 pages, 18 figures
Universal Drift Correction for Multidimensional Scanning Microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Sangjoon Lee, William Millsaps, Dasol Yoon, Caitlyn Obrero, Guoliang Hu, Corrie Barnes, Cedric Lim, Andrew Barnum, Arthur R. C. McCray, Colin Ophus
In scanning microscopy, drift causes the specimen to be sampled at positions displaced from the nominal probe positions. This displacement alters the spatial assignment of the recorded signals and biases quantitative measurements across two-dimensional imaging, channel-resolved spectroscopic mapping, and scan-position-resolved diffraction analysis. Here, we extend orthogonal-scan drift correction from 2D images to spectrum images and diffraction datasets. We demonstrate how to recover probe positions using either differently oriented multidimensional scans or structural reference images. The recovered positions are used either to resample the multidimensional data onto a regular grid or to assign each recorded signal to its corrected coordinate. Our method combines affine and non-rigid correction, requires no prior structural model, and is implemented as open-source, GPU-accelerated software that reduces processing times by two to three orders of magnitude, enabling routine and automated drift correction for quantitative multidimensional microscopy.
Materials Science (cond-mat.mtrl-sci), Computer Vision and Pattern Recognition (cs.CV)
Systematic Evolution of Magnetic Anisotropy and Crystal-electric-field Ground States in SmTr2Ge2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Ryuji Higashinaka, Kokoro Higo, Tatsuma D. Matsuda, Yuji Aoki
We investigated the crystal-electric-field (CEF) states in SmTr2Ge2 (Tr= Co-Cu and Ag) with the ThCr2Si2-type structure by magnetization and specific heat measurements. The magnetic anisotropy evolves systematically with Tr, changing from an easy ab plane for Tr = Co and Ni to an easy c axis for Tr = Cu and Ag. Combined analyses of the low-temperature susceptibility and magnetic entropy indicate a level crossing of the CEF ground state between Ni and Cu, together with a systematic evolution of the first excited CEF energy. The evolution of the magnetic properties correlates with changes in local structural parameters, providing an experimental basis for discussing how the ligand environment around the Sm ion is related to the 4f electronic state.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages
J. Phys. Soc. Jpn. 95 (2026) 104711
Thorium-229 as a Phonomagnetometer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Martin Pimon, Andreas Grüneis, Thorsten Schumm, Kjeld Beeks
Thorium-229 possesses the only known low-energy nuclear transition suitable for spectroscopy with narrowband VUV lasers. While previous experiments have focused on application as a nuclear clock, this transition also offers a route to high-accuracy magnetometry. Experimental observations of magnetic fields generated by phonons carrying angular momentum remain inconclusive, highlighting the need for quantitative tests of the underlying physical mechanisms. In this article, we propose doping thorium-229 into a solid-state host to probe phonomagnetic fields in situ. We identify Na$ _2$ ThF$ _6$ , a chiral stoichiometric thorium compound, as a promising host material and evaluate its spectroscopic sensitivity to magnetic interactions under two excitation schemes: driving degenerate phonon modes with a circularly polarized laser, and applying a temperature gradient. Density functional theory simulations combined with quantitative estimates suggest that the temperature-gradient scheme yields a magnetic signal that appears too weak to be measurable, while a circularly polarized, high-intensity THz/VUV pump-probe driven phonomagnetic response may approach the shot-noise-limited detection threshold. While experimental challenges remain, the unique suitability of thorium-229 provides a testable pathway toward detecting phonomagnetic fields in a solid-state platform.
Materials Science (cond-mat.mtrl-sci)
11 pages, 6 figures, 1 table
A Bonded-Particle Discrete-Element Model with Self-Gravity for the Collision and Reaccumulation of Rubble-Pile Asteroids: Formulation and Numerical Protocol
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
I present a discrete-element approach developed to study the collisional and gravitational evolution of small self-gravitating granular aggregates. Each body is represented as a composite of cohesively bonded spherical grains, so that fragmentation and reaccumulation emerge from the microscopic competition between short-range dissipative contact forces, an irreversible bond-breaking criterion, and pairwise Newtonian self-gravity summed over every particle pair, including those internal to a single body. A numerical experiment is described: a random-sequential packing procedure that generates two bonded spherical aggregates, a controlled two-body encounter with tunable approach speed and impact parameter, and a systematic parameter sweep designed to map the conditions under which two bodies launched from rest under their mutual gravity alone either merge into a single remnant or fail to settle after a low-speed encounter. Of the 125 simulated collisions, 56.8% result in the formation of a single residue. The cohesive network remains intact for $ \Pi_\sigma\lesssim0.036$ , is partially damaged with dispersion determined by the contact damping ratio, and breaks completely for $ \Pi_\sigma\approx3.59$
Soft Condensed Matter (cond-mat.soft), Earth and Planetary Astrophysics (astro-ph.EP)
Infrared laser stimulated broadband white emission of transparent Cr:YAG ceramics obtained by solid state reaction sintering
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
M. Chaika, R. Tomala, W. Strek
In the present work, the Light Induced White Emission (LIWE) was investigated as one of the sources of laser loss in transparent Cr:YAG ceramics. We have found that transparent Cr:YAG ceramics is capable of generating bright LIWE at excitation powers above a certain threshold. Intensity of LIWE strongly depends on the excitation power and ambient pressure. The host temperature estimated from Cr3+ luminescence was found to be below 600°C, while the most intense white emission was found between 50-400°C. The mechanism of the laser induced white emission was discussed in terms of Intervalence Charge Transfer (IVCT) in chromium mixed valence pair.
Materials Science (cond-mat.mtrl-sci)
Chaika, M. A., Tomala, R., & Strek, W. (2021). Infrared laser stimulated broadband white emission of transparent Cr: YAG ceramics obtained by solid state reaction sintering. Optical Materials, 111, 110673
Emergence of Nanoscale Modulation in Liquid Crystals as a Result of Short-Range Order Parameter Condensation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
The discovery of the twist-bend nematic phase in liquid crystals composed of bent-core and dimeric molecules has revealed an unexpected mechanism for the spontaneous formation of nanoscale periodic structures in soft condensed matter. Unlike conventional liquid-crystalline phases, the twist-bend phase exhibits a nanoscale heliconical modulation despite the absence of molecular chirality. In this note, dedicated to the late R. Meyer, we discuss a Landau phenomenological interpretation of this phenomenon. The central idea is that a short-range orientational order parameter undergoes condensation, giving rise to a heliconical structure characterized by a finite wave vector. We emphasize that the conventional nematic order is already long-ranged, whereas the additional order parameter describes local orientational correlations hidden within the nematic state. The resulting phase transition bears a close analogy to the de Gennes theory of the nematic–smectic-A transition. Fluctuation effects are expected to drive the transition weakly first order. The theory also predicts a new Goldstone mode associated with the spontaneously broken continuous symmetry of the heliconical state
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
6 pages
Representation-Aware Transport-Information Measure for Non-inclusive Discrete Supports
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Information-theoretic measures for comparing probability distributions are widely used across physics and other fields. When two discrete distributions have non-inclusive supports, however, the Kullback-Leibler (KL) divergence is in general not directly applicable, and various alternative divergences and distances have been introduced. These measures compare the resulting distributions themselves, but do not generally retain information about the representation transformations by which the discrete distributions are generated from underlying continuous ones. Here we introduce a representation-aware transport-information measure for discrete distributions with non-inclusive supports, formulated based on the standard KL divergence. We consider two continuous reference distributions, each transformed into a discrete representation through its own discretization scheme. Rather than comparing only the resulting discrete distributions or their continuous references, we additionally retain local information associated with the representation-change schemes. The resulting measure can therefore distinguish discrete representations that may have identical discrete probability landscapes but originate from different continuous references or discretization schemes. The construction is based on the transport-information cost of continuous-to-discrete representation in the framework of unavoidable canonical nonlinearity (UCN). UCN provides a non-arbitrary correspondence between the transport cost of discretization as an extrinsic geometric operation and the information-theoretic indistinguishability of nearby continuous distributions, thereby allowing a discrete representation to be associated with a local family of underlying continuous distributions on the statistical manifold.
Statistical Mechanics (cond-mat.stat-mech)
5 pages
Multiorbital periodic Anderson model for CeRh2As2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Nico A. Hackner, Changhee Lee, P. M. R. Brydon
CeRh2As2 is a heavy-fermion superconductor that exhibits distinct low- and high-field superconducting phases, widely interpreted as reflecting a field-induced change in the parity of the order parameter. However, the superconductivity develops in close proximity to magnetic order whose microscopic origin and nature remain unclear. Moreover, the low-lying crystal-electric-field-split doublets of the Ce 4f electrons appear to realize an unusual “quasi-quartet” structure. This has motivated proposals that quadrupolar degrees of freedom play an important role in the low-temperature physics. Here we develop a microscopic heavy-fermion description of CeRh2As2 that incorporates both the quasi-quartet structure and the nonsymmorphic symmetry. Within a multiorbital periodic Anderson model, we include the lowest-lying $ \Gamma_7$ and $ \Gamma_6$ doublets of the Ce 4f electrons, and allow for nonlocal hybridization with the conduction d electrons. Single occupancy of the 4f states is enforced within the rotationally invariant slave-boson formalism. Adopting a mean-field treatment, we first show that the effective low-energy Hamiltonian is accurately captured by a single-orbital tight-binding model, justifying the minimal descriptions widely employed in the literature. Allowing for a magnetic ground state, we find that our model displays metallic $ \mathbf{Q}=(\pi,\pi)$ antiferromagnetic order over a wide parameter regime. Ferromagnetic solutions also occur, but in a smaller region of parameter space and with greater sensitivity to carrier concentration and the form of the f-d hybridization. Quadrupolar moments appear only within magnetically ordered phases and are generally small, becoming substantial only when the $ \Gamma_7$ and $ \Gamma_6$ doublets are nearly degenerate. Our results provide a microscopic basis for understanding the itinerant heavy-fermion physics and ordered phases of CeRh2As2.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
17 pages, 7 figures, 2 tables
Electrically controlled spin-splitting and asymmetric tunnel magnetoresistance in anti-altermagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Anti-altermagnets (AAMs) are a recently identified class of layered magnetic materials where opposite spin-splitting in adjacent layers creates a globally spin-degenerate band structure, rendering conventional spectroscopic detection highly difficult. In this paper, we theoretically demonstrate an all-electrical method to manipulate and probe this hidden magnetic order using a dual-gated transport junction. By applying a perpendicular displacement field, we break the spatial inversion symmetry of the lattice, explicitly lifting the global spin degeneracy. We attach ferromagnetic (FM) leads on either side of the AAM. Using quantum transport calculations, we show that this gate-induced spin-splitting manifests as a strongly asymmetric tunnel magnetoresistance (TMR) as a function of the lead magnetization. We identify specific crystallographic orientations where the TMR retains its symmetry despite the fully split bands, a direct consequence of exact momentum-space compensation. We further reveal that Rashba spin-orbit coupling guarantees robust, highly directional transport asymmetries even in the absence of an explicit chemical potential mismatch between the layers. Our findings establish a clear, electrically tunable framework for exploiting AAMs in next-generation spintronic architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
4 pages, 3 captioned figures. Comments are welcome
Binary magnetism and directional magnon transport in alkali-doped CrI$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Cihan Bacaksiz, Maarten Soenen, Denis Sabani, Rai Maciel de Menezes, Milorad V. Milosevic
The recent realization of two-dimensional (2D) magnets, with CrI$ _3$ as a pioneering example, has opened new avenues in the fields of 2D materials and magnetism. This breakthrough has been followed by extensive efforts to manipulate and exploit their magnetic properties. In this work, we investigate the adsorption of alkali-metal atoms as a route to control the magnetic behavior of monolayer CrI$ _3$ . We show that, upon adsorption, alkali-metal atoms donate an electron to the CrI$ _3$ layer, leading to the formation of inequivalent Cr sites, with one Cr atom exhibiting an enhanced magnetic moment of $ 4\mu_B$ , while the other retains its typical $ 3\mu_B$ moment. These modifications significantly alter the magnetic exchange interactions, including the emergence of anisotropic exchange and Dzyaloshinskii–Moriya interactions (DMI). Consequently, the doped systems exhibit non-collinear magnetic ground states, modified temperature-dependent magnetism, and anisotropic spin-wave propagation, with a preferred propagation direction that becomes increasingly pronounced with increasing dopant size. Furthermore, an asymmetry between spin-wave propagation in opposite directions is observed, giving rise to a diode-like effect, particularly for heavier dopants. This behavior is attributed to the enhanced DMI, which breaks the symmetry of the magnon dispersion. These results demonstrate that alkali-metal doping provides an effective route to tune anisotropic and nonreciprocal magnonic properties in two-dimensional magnetic materials.
Materials Science (cond-mat.mtrl-sci)
Measurement protocol for non-adiabatic geometric phases of Floquet states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Carlos Martín-Fernández, Gloria Platero, Sigmund Kohler
Periodically time-dependent quantum systems have Floquet solutions. They consist of a phase factor and a Floquet mode which shares the periodicity of the driving. Consequently, any such solution possesses a non adiabatic geometric phase known as the Aharonov-Anandan (AA) phase. It is gauge-invariant and, therefore, is experimentally accessible. We propose a protocol for the measurement of AA phases based on the adiabatic change of the phase of the non-adiabatic driving. We argue that the experimental requirements of the protocol are those of previous measurements of adiabatic phases.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
12 pages, 7 figures
Collective order reorganizes dissipation and powers an active engine
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
Michael Riedl, Vincent Wattiez, Étienne Fodor, Jan Brugués, Francesco Romanò
Motile active matter systems, from animal groups to synthetic particles, exhibit spontaneous self-organized transitions between disordered and ordered collective states. These transitions are driven by continuous energy injection, yet how energy consumption and dissipation change during these transitions remains poorly understood due to the challenge of measuring individual energetic fluxes. Here, we introduce a minimal experimental system of synthetic motile spheres that enables the first time-resolved power-budget characterization of collective motion. We show that the transition to an ordered state is accompanied by increased locomotion efficiency and a reorganization of dissipation pathways, shifting dissipation from internal friction to external slip with the environment. Leveraging this energetic reorganization, we construct an active engine powered by collective motion, capable of performing mechanical work against an external load. These findings establish energetic fluxes as quantitative observables for understanding collective state transitions and demonstrate how collective order can be harnessed for work extraction in active matter.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Experimental realization of the minimal two-dimensional multi-orbital kagome model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Bing Liu, Arka Bandyopadhyay, Manish Verma, Jonas Erhardt, Tim Wagner, Jing Qi, Kilian Strauß, Domenico Di Sante, Carmine Ortix, Simon Moser, Jörg Schäfer, Ronny Thomale, Giorgio Sangiovanni, Ralph Claessen
Kagome materials have emerged as a major platform for correlated and topological quantum matter, hosting flat bands, Dirac dispersions and van Hove singularities rooted in frustrated lattice geometry. While their essential physics is epitomized by the canonical single-orbital kagome model, real kagome materials are intrinsically multi-orbital and typically chemically and structurally complex, with additional three-dimensional coupling making kagome geometry and orbital degrees of freedom difficult to disentangle. Here we realize a truly two-dimensional, elemental two-orbital kagome system in monolayer Sb on SiC(0001). Substrate-induced orbital filtering isolates the in-plane Sb p_x/p_y orbitals into a six-band kagome manifold, establishing a chemically simple, minimal platform for multi-orbital kagome physics. We demonstrate two consequences that distinguish this system from the canonical single-orbital model. First, chemically enforced half filling pins the Fermi level to a closed nodal line, whose finite density of states drives a unit-cell-conserving breathing instability and opens a giant insulating gap. Second, we uncover orbital-resolved atomic obstruction: individual orbital-derived manifolds realize obstructed atomic limits, whereas their combined half-filled valence manifold is non-obstructed. Our results establish kagome antimonene as a benchmark system for exploring orbital-driven electronic, structural and topological kagome physics in the genuine two-dimensional limit.
Materials Science (cond-mat.mtrl-sci)
The renormalization group for a slab model of the spin reorientation transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
In 1975, Polyakov invented a renormalization group algorithm for treating the problem of a classical isotropic planar Heisenberg ferromagnet. Here we define a tool - “parallel transport of frames” - that extends Polyakov’s original renormalization group method to local magnetic anisotropies and, most significantly, the non-local dipolar interaction. We apply this tool to the problem of the spin reorientation transition in an ultrathin ferromagnetic slab with finite thickness. We find that integrating out the short wavelength spin wave fluctuations generates two local anisotropies that are absent from the microscopic dipolar energy Hamiltonian. Taking them into account yields the correct topology of the spin reorientation transition line, as observed experimentally and in numerical simulations.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
23 pages (main text 7 pages, 1 figure; Supplemental Material included, 16 pages, 1 figure). Submitted to Papers in Physics
Synthetic Berry curvature in atom-cavity systems
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-28 20:00 EDT
Zheng Tang, Rui-Lin Zhang, Xiaotian Nie, Li Chen, Wei Zheng
In atom-cavity systems, mean field theory is widely used, in which the quantum cavity operator is replaced by a classical amplitude. Then the problem is converted into atoms moving in a self-consistent potential. The mean field treatment captures the physics of cavity mediated interactions, and predicts the self-organized superradiant phase. In this work, however, we show that it fails for certain atom-cavity coupling: it predicts zero ground state atomic current where the fully quantum calculation exhibits a finite one. We find that the origin of this failure is the non-zero Berry curvature in the synthetic dimension spanned by the photon Fock ladder and real space. In this synthetic picture, the atomic current can be understood as Hall response of cavity detuning, whereas mean field collapses this dimension and discards the atom–photon correlations required for its Hall response. The same beyond-mean-field geometry predicts Laughlin-like photon generation under adiabatic flux insertion. Our work identifies synthetic Berry curvature as a concrete mechanism for the breakdown of static mean field in atom–cavity physics.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el)
Plasmonic Modes in hybrid Josephson Junction Arrays
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Alex Kirchner, Simon Feyrer, Vjeko Dimić, Johanna Berger, Davide Curcio, Giorgio Biasiol, Michael Prager, Matthias Kronseder, Dominique Bougeard, Nicola Paradiso, Christoph Strunk, Leandro Tosi
We present microwave characterization measurements of Josephson junction arrays (JJAs) based on epitaxial Al-InAs quantum well heterostructure. The Josephson inductance of the constituent planar junctions can be derived by probing the low-energy plasmon modes of these devices. Applying an out-of-plane magnetic field gives rise to a Fraunhofer-like diffraction pattern, from which the current-phase relation and the effective transparency can be extracted. JJAs can be used to achieve high inductances, suitable for the implementation of quantum circuits. They also provide an excellent test-bed for studying the microscopic excitations of hybrid superconductor-semiconductor devices associated with the presence of Andreev states. Here, we demonstrate their tunability over a broad range of out-of-plane magnetic fields.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
12 pages, 7 figures
Unraveling the electronic structure and the oxygen $K$-edge x-ray absorption near-edge structure spectrum of DyFeO$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
G. Gebreyesus, Eric Macke, Pietro Delugas, Weiguo Jing, Banani Biswas, Carlos A. F. Vaz, Christof W. Schneider, Iurii Timrov
Rare-earth orthoferrites such as DyFeO$ _3$ exhibit a rich interplay between localized rare-earth and transition-metal moments, giving rise to complex magnetic phases and magnetoelectric phenomena. Understanding their electronic and spectroscopic properties from first principles requires an accurate description of the localized Fe-$ 3d$ and Dy-$ 4f$ states and their hybridization with O-$ 2p$ states. Here, we combine first-principles calculations and x-ray absorption near-edge structure (XANES) measurements to investigate the electronic structure and the O $ K$ -edge spectrum of DyFeO$ _3$ . We employ density-functional theory (DFT) with Hubbard $ U$ corrections (DFT+$ U$ ) determined from first principles using density-functional perturbation theory, the HSE06 hybrid functional, and orbital-resolved DFT+$ U$ with Hubbard parameters calibrated to reproduce the electronic structure computed using HSE06. We find that standard DFT+$ U$ , despite improving the band gap, substantially underestimates the crystal-field splitting of the unoccupied Fe-$ 3d$ states and consequently fails to accurately reproduce the separation of the two lowest-energy features in the O $ K$ -edge spectrum. HSE06 provides a more balanced description of the relevant electronic states, including the Fe-$ 3d$ crystal-field splitting. Mapping the corresponding electronic structure onto orbital-resolved DFT+$ U$ yields a spectrum that remarkably reproduces the two lowest-energy experimental features and captures the main characteristics of the spectrum at higher energies. These results establish the low-energy O $ K$ -edge features as a sensitive probe of the Fe-$ 3d$ crystal-field splitting, while showing that the localized Dy-$ 4f$ states leave no distinct spectral fingerprints despite their importance for the magnetic properties.
Materials Science (cond-mat.mtrl-sci)
2D target search with boundary-induced resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Most studies of stochastic search processes with resetting focus on spontaneous resetting events that occur at a random sequence of times typically generated by a Poisson process. One of the major consequences of spontaneous resetting is that it yields a finite mean first passage time (MFPT) in unbounded domains, resulting in an optimal resetting rate that minimises the MFPT. An optimal resetting rate can also occur in bounded domains provided that the reset point is not too far from the target. Recently, there has been growing interest in event-based rather than spontaneous resetting, where resetting is triggered when a specific threshold is reached. Identifying the threshold with a physical non-target boundary then leads to so-called boundary-induced resetting. In this paper, we explore the effects of boundary-induced resetting on single-particle diffusive search in a two-dimensional (2D) bounded domain $ \Omega$ containing one or more small interior targets. The interior target boundaries are totally absorbing, whereas the exterior boundary $ \partial \Omega$ is sticky. That is, whenever the particle reaches a point on $ \partial \Omega$ it remains attached for a random waiting time $ \tau$ after which it immediately resets to a fixed interior point $ \x_0\in \Omega$ . Using renewal theory, matched asymptotic analysis and Green’s functions we calculate the unconditional MFPT for absorption by any of the targets and compare this with the corresponding MFPT of a search process on the same domain with a reflecting surface $ \partial \Omega$ and no resetting. We show that boundary-induced resetting only reduces the MFPT relative to the no resetting case if the searcher’s reset point $ \x_0$ is sufficiently close to one of the targets.
Statistical Mechanics (cond-mat.stat-mech), Analysis of PDEs (math.AP), Probability (math.PR)
25 pages, 10 figures
Thermodynamics of the $q$-deformed Kittel–Shore model for spin-1 particles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
Quantum algebras ($ q$ -algebras) have been used in the literature to deform spin-chain models. In particular, in previous works by the present authors, the Kittel–Shore Hamiltonian was deformed using $ \mathfrak{su}_q(2)$ algebra. The deformed Hamiltonian was presented for a general spin, and the thermodynamic properties were studied for spin-1/2 particles. In this paper, we focus on the $ q$ -deformation of the Kittel–Shore model for spin-1 systems. We analyse the impact of this deformation on the thermodynamic properties and phase transitions of the system as a function of the deformation parameter $ q$ . Specifically, we study the specific heat, magnetic susceptibility, and magnetisation, including a detailed analysis of the Curie temperature characterising the ferromagnetic phase. Furthermore, a finite-size scaling analysis is conducted for both the ferromagnetic and antiferromagnetic cases. Results are systematically compared with those of the undeformed model to reveal the physical effects of the $ q$ -deformation.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
47 pages, 51 figures
A Flatness-Generalization Relation in the Teacher-Student Tree-Committee Machine
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2026-09-28 20:00 EDT
Brandon Livio Annesi, Davide Straziota, Enrico Maria Malatesta
The flatness of the loss landscape at a minimizer is a widely used heuristic for reasoning about neural-network generalization, yet evidence for this relation is mostly empirical and controversial. We study this relation in a teacher-student tree committee machine, where both the ERM estimator and the Hessian spectrum are analytically tractable in the proportional high-dimensional limit. First, we use a zero-temperature Gibbs formulation to obtain predictions for the observables of the typical minimizers of the empirical loss. Secondly, we use Edwards-Jones formalism to derive the limiting Hessian resolvent around these typical minimizers. All predictions agree with finite-size gradient-descent simulations. Finally, we study three measures of flatness, namely the left and right edges and the spectral mean, and check if a decrease in generalization error as the dataset size is increased corresponds to an increase in flatness. We find that the answer strongly depends on the learning task and on the ratio of the number of parameters to the number of data points. In regression, the spectral mean and right edge correlate with the generalization error, while the left edge does so only in the overparametrized regime. In classification this correlation reliably holds only in the highly overparametrized phase, while for underparametrized networks it can even reverse.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (cs.LG), Machine Learning (stat.ML)
Shape enantiomerism in semi-rigid polymer liquid crystals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
S. Biswas, W. S. Fall, H. H. Wensink
Weakly flexible, directed polymers can adopt a potentially infinite variety of conformations, some of them chiral. We develop a second-virial theory for semi-rigid polymers embedded in a nematic environment based on the assumption that the chains possess no intrinsic molecular chirality but can take on weakly helical conformations of either handedness. We demonstrate how these transient helical fluctuations can be exploited to predict the degree of chain stiffening induced by molecular crowding. The theoretical predictions are in good agreement with large-scale molecular dynamics simulations of bead-spring polymers with tunable backbone flexibility. Although both theory and simulations rule out spontaneous global chiral symmetry breaking imparted by chain conformations alone, they do reveal that polymers can develop pronounced enantiomeric shapes. Nematic fluids of semi-rigid polymers can be viewed as compensated cholesterics composed of transiently helical polymers with zero enantiomeric excess. By quantifying the degree of compensated chiral order developed over a broad range of concentrations and persistence lengths, two distinct regimes of weak and strong enantiomerism can be identified. A crossover between the two occurs when the chain persistence length drops below roughly three times the contour length.
Soft Condensed Matter (cond-mat.soft)
13 pages, 10 figures
Rydberg-Atom-Mediated Strong Antisymmetric Spin Exchange in Molecular Arrays
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-28 20:00 EDT
Yunqing Jiao, Jin-Zhu Jiang, Bo-Wen Guan, Jie Ma, Liantuan Xiao, Chi Zhang, Weibin Li, Feng Mei, Suotang Jia
Ultracold molecular systems have recently emerged as a versatile platform for quantum computation and simulation. Spin-exchange interactions arising from direct molecular dipolar interactions constitute the key mechanism for generating quantum entanglement and simulating quantum spin models. However, the relatively small electric dipole moments result in weak spin-exchange couplings, fundamentally limiting the speed of quantum information processing and interaction cycle of many-body dynamics. Here, we introduce a framework that employs Rydberg atoms with large electric dipole moments to mediate strong interactions between molecules in optical tweezer arrays that enables individually laser addressing both the Rydberg atom and molecules. Our result reveals that the mediated coupling can realize an effective molecular spin-exchange interaction with an intrinsic Dzyaloshinskii-Moriya character, with the Rydberg atoms dynamically decoupled from the molecular degrees of freedom, and the effective interaction strength enhanced by up to three orders of magnitude. We further demonstrate its versatility through rapid entanglement generation, high-fidelity two-qubit gate operations, and the realization of non-equilibrium symmetry-protected topological phase with long-lived edge coherence. Our work establishes a route toward strong molecular spin interactions and opens opportunities for fast, scalable quantum information processing and quantum simulation of long-time non-equilibrium quantum many-body physics in optical tweezer arrays of ultracold molecules.
Quantum Gases (cond-mat.quant-gas)
Slow-fast dynamics of the McKean model with stochastic resetting and diffusion
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
In this paper we investigate the combined effects of stochastic resetting and diffusion on a slow–fast dynamical system given by the piecewise-linear McKean model. That is, the fast variable $ v$ is subject to Gaussian white noise with effective diffusivity $ D$ and is reset to a fixed value $ v_r$ at a random sequence of times generated from a Poisson process with rate $ r$ . Assuming that resetting occurs on the fast timescale, we freeze the slow variable (w) under an adiabatic approximation and determine the resulting non-equilibrium stationary state (NESS) of the fast variable as the solution of a modified Fokker–Planck equation. We show that the NESS can be expressed in terms of parabolic cylinder functions, whose asymptotic behavior allows us to recover the corresponding NESS without diffusion in the small-diffusion limit. The NESS is used to derive an averaged equation for the slow dynamics, whose solution converges to a stable fixed point (w^\ast) that depends on (D), (r) and (v_r). This fixed point effectively determines the long-time behaviour of the full system. Finally, we analyze the regime in which resetting occurs on the same timescale as the slow variable. We show how the slow variable now undergoes noisy oscillations due to resetting-induced switching between branches of the fast nullcline and derive the corresponding NESS for $ w$ in the non-diffusive case.
Statistical Mechanics (cond-mat.stat-mech), Quantitative Methods (q-bio.QM)
19 pages, 22 figures
Modern triad for magnetic material science: geometric shape, electronic bands and spin textures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Denys Makarov, Oleksandr Pylypovskyi, Rui Xu, Carmine Ortix
To enable novel concepts in nanotechnologies, it is insightful to design materials with qualitatively new performances originating from recent discoveries in fundamental material science and physics. Curvilinear magnetism emerged as a tool to design chiral and anisotropic responses of materials at the nanoscale using the effects of the geometric shape and topology of the object. This concept is distinct yet complementary to material screening, which is primarily based on the optimization of intrinsic microscopic properties to modify magnetic textures for specific applications. Contemporary curvilinear magnetism focuses on mean-field micromagnetics, while the explicit contribution of the lattice structure and electronic degrees of freedom remains beyond consideration. In this review, we will emphasize on the effects which appear when this coupling is accounted for and that have resulted in novel concepts for the design of ``metageometric’’ materials. Further development of this field will provide appealing technological prospects for fundamental understanding of curvilinear magnetic nanostructures and their applications in energy efficient and scalable nanoelectronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Nature Nanotechnology, 21, 1068-1082 (2026)
Current-voltage characteristics and resistive switching in epitaxial La${0.67}$Sr${0.33}$MnO$3$/SrMnO$3$/La${0.67}$Sr${0.33}$MnO$_3$ multilayer
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
A. G. A. Rahman, R. K. Patel, Chandrani Nath, A. K. Pramanik
In present study, we investigate the structural properties and current-voltage ($ I$ -$ V$ ) characteristics of an epitaxial multilayer composed of La$ _{0.67}$ Sr$ _{0.33}$ MnO$ _3$ (25 nm)/SrMnO$ _3$ (70 nm)/La$ _{0.67}$ Sr$ _{0.33}$ MnO$ _3$ (25 nm), grown on different substrates i.e., SrTiO$ _3$ (100), LaAlO$ _3$ (100), Si (100). The used substrates not only have different chemical compositions in line with the film materials, also they have different lattice parameters which would tune the material chemistry and lattice strain at the interface significantly. Our $ I$ -$ V$ measurements reveal distinct electrical behaviors depending on the substrate. The multilayers grown on oxide SrTiO$ _3$ (100) and LaAlO$ _3$ (100) substrates exhibit regular $ I$ -$ V$ with slight nonlinearity at low applied voltages. In contrast, $ I$ -$ V$ in multilayer with Si(100) substrate exhibits large asymmetry and notable resistive switching (RS) behavior at room temperature, where a resistance ratio around 10 between the high resistance state (HRS) and low resistance state (LRS) is observed. While the observed $ I$ -$ V$ behavior is sensitive to substrate-induced interfacial disorder and formation of trap bands within bandgap of SrMnO$ _3$ , the present results have potential applications in future memory and memristive devices.
Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures
ACS Appl. Electron. Mater. 7, 7679 (2025)
Orbital photoinduced Faraday effect in a lattice of conducting disks
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
We present a theoretical study of pump-induced Faraday and Kerr rotation in a two-dimensional lattice of conducting disks. We propose a mechanism of Faraday and Kerr responses in which a circularly polarized pump directly induces a high-frequency Hall component $ \sigma_{xy}=-\sigma_{yx}$ of the electron conductivity tensor at the probe frequency. Microscopically, $ \sigma_{xy}$ originates from the third-order nonlinear response of the electron gas rather than from the real magnetic field created by solenoidal charge currents in the inverse Faraday effect. We show that the Faraday and Kerr rotation angles are significantly enhanced when the pump and probe frequencies are tuned close to the plasmon resonance of the disks, reaching $ \sim 0.1^\circ$ per 1~kW/cm$ ^2$ of incident pump intensity in the terahertz range. This mechanism can explain recently observed giant pump-induced Faraday rotation in graphene disk lattices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures
Electron paramagnetic resonance of Dy${^3+}$-doped CaWO$_4$: spin Hamiltonian, crystal-field analysis, and linear electric field effect
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Achuthan Manoj Kumar, Larissa Aboudem-Joumessi, Remy Dassonneville, Adrien Savoyant, Karolina Waszowska, Pengrui Jiao, Patrice Bertet, Philippe Goldner, Sylvain Bertaina
We report an electron paramagnetic resonance (EPR) study of Dy$ {^3+}$ in CaWO$ 4$ single crystals spanning dopant concentrations from 80ppb to 247ppm. The $ g$ factors of the ground Kramers doublet at the $ S_4$ point-group site, $ g\parallel = 7.22 \pm 0.01$ and $ g_\perp = 5.45 \pm 0.01$ , and the hyperfine constants of \ce{^{161}Dy} and $ ^{163}$ Dy are determined with an order-of-magnitude improvement in precision over the only previous report. A crystal-field analysis constrained jointly by published optical levels and by the measured $ g$ tensor identifies the ground doublet as the lower branch of an anticrossing between the near-degenerate $ |{\pm}11/2>$ and $ |{\mp}13/2>$ states, and explains why optical data alone left the $ g$ values unconstrained. \add{The same parameter set, tested on the excited multiplets of the $ ^6H$ term, reproduces the $ {}^6H_{13/2}$ crystal-field levels better than the optical parameters themselves.} The angular dependence of the linewidth in the $ ab$ plane reveals broadening by random internal electric fields through the linear electric field effect. Calibrating these fields with the residual Er$ ^{3+}$ present in the same crystals yields the first electric-field coupling parameters of Dy$ ^3+$ , $ (B_{31}^2+B_{36}^2)^{1/2} = (34\pm5)\times10^{-6}$ ~cm/V, three times the Er$ ^{3+}$ value and the largest reported for a rare-earth ion in this this http URL residual linewidth and the concentration-dependent lineshape asymmetry follow the quadratic field scaling expected for a second-order Stark shift, which escapes the inversion-site cancellation constraining the linear effect. Both couplings trace back to the $ \sim 20$ ~cm$ ^{-1}$ gap to the first opposite-symmetry doublet, a consequence of the dense crystal-field structure of the $ J=15/2$ manifold.
Materials Science (cond-mat.mtrl-sci)
The Paper-Stack Trampoline: Acoustic Restitution in Layered Media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
Manou Liesker, Colton Kawamura, Maria Kieft, Joshua A. Dijksman, Antoine Deblais
A ball bouncing on a thicker cushion should bounce less. We show that this is not always so . Measuring the coefficient of restitution $ e$ of a steel ball dropped on a stack of $ N$ sheets of standard A4 printer paper, we find that $ e$ first drops, then rises to a pronounced maximum, and only then decreases towards a minimum. The maximum occurs where the acoustic round trip through the stack matches the contact time of the impact. For a contact set by the stack itself, one recovers the classical bar-impact condition of a stack-to-ball mass ratio of order one. Bar impact, however, predicts only a weak recovery, insensitive to the surrounding gas. For paper stacks, the recovery is large and no maximum is resolved when the stack is evacuated: the air trapped between the sheets, not the paper alone, makes the stack a trampoline.
Soft Condensed Matter (cond-mat.soft)
12 pages, 12 figures
First-principles calculations of the thermodynamic factor of multicomponent alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Damien K. J. Lee, Shashank Saxena, Anton Van der Ven, Anirudh Raju Natarajan
Computing non-dilute diffusion coefficients from Onsager transport coefficients of a multicomponent alloy requires the thermodynamic factor, which measures the curvature of the free energy with respect to composition. As diffusion in metals is mediated by vacancies, the curvature that matters is not that of the vacancy-free alloy, which is straightforward to compute, but that of an alloy carrying a dilute concentration of vacancies. The resulting matrix is nearly singular, and composition fluctuations from which it is obtained converge slowly in Monte Carlo simulations. Here we develop two routes that avoid sampling vacancy composition fluctuations. The first constructs the thermodynamic factor from two quantities, the free-energy curvature of the vacancy-free alloy and the vacancy concentration. The second truncates the semi-grand canonical partition function at a single vacancy and recovers the full thermodynamic factor of the vacancy-containing alloy. The same separation shows that the largest eigenvalue of the diffusion matrix is the vacancy tracer diffusion coefficient for any number of components and any degree of non-ideality, while the remaining eigenvalues scale with the vacancy concentration. Across binary through quinary alloys of the Hf–Mo–Nb–Ti–Zr system, both routes reproduce eigenvalues and eigenvectors of diffusion matrices obtained from fully converged Monte Carlo simulations. The single-vacancy expansion reaches this accuracy with roughly one tenth of the sampling effort. A scaling relation extends both routes to local vacancy chemical potentials away from equilibrium, without additional simulations. These results allow thermodynamic descriptions from atomistic models or CALPHAD assessments to be used directly in mesoscale simulations of mass transport.
Materials Science (cond-mat.mtrl-sci)
Electron lattice potentials for ultracold atoms using circular Rydberg orbitals
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-28 20:00 EDT
Aileen A. T. Durst, Einius Pultinevicius, Homar Rivera-Rodríguez, Tilman Pfau, Matthew T. Eiles, Florian Meinert
Recent advances in experiments using individually trapped atoms have enabled precise control over circular Rydberg electrons with exceptionally long lifetimes. We show that these giant and stable electron orbits can form toroidal lattice potentials for ultracold atoms with a period set by the electron’s de Broglie wavelength. Unlike conventional static optical lattices, this electron lattice is formed via the electron-atom interaction, which mixes Rydberg circular states with opposite azimuthal phase winding into a standing electronic matter wave. The lattice phase is thereby intrinsically coupled to the atom position. For a pair of atoms, this results in ballistic tunneling motion in the two-atom spatial correlations along the ring, while the single particle dynamics is essentially free rotation. We simulate the dynamics for an experimentally realistic setting that exploits optical tweezers for individual atom control. Our results open a route toward incorporating long range atom-atom interactions mediated by a single electron and, ultimately, realizing small Bose and Fermi gases confined in these microscopic electronic atom traps.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Vibrational Mpemba relaxation in a linear damped elastic system
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-09-28 20:00 EDT
We show that a linear damped elastic system can display a Mpemba-like reversal of vibrational relaxation without any nonlinear constitutive response or amplitude-dependent damping. The mechanism is purely modal. For a one-dimensional Kelvin–Voigt elastic medium, the decay rate of the $ n$ -th vibrational mode scales as $ \gamma_n\propto n^2$ . We formulate relaxation in terms of a positive modal envelope energy, thereby excluding crossings caused merely by oscillation phase. A one-parameter family of initial states is then constructed such that increasing the initial elastic excitation simultaneously reduces the projection onto the slow fundamental mode. In the invariant two-mode subspace, the relaxation-order crossing is obtained analytically and, for this family, occurs at a universal dimensionless time independent of the selected pair of initial states. In the limiting case where the slowest mode is absent, the dominant relaxation rate changes discontinuously, yielding a direct vibrational analogue of the strong Mpemba effect. We further show that the same relaxation-order reversal occurs in the ordinary mechanical vibrational energy, which decreases monotonically despite retaining the oscillatory dynamics of the underlying modes.
Soft Condensed Matter (cond-mat.soft)
11 pages, 3 figures
Multiscale computational study of the dielectric response of semi-crystalline polyethylene with chemical defects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Roshal Perepadan Shaju (1), Guido Roma (1), Xavier Colin (2) ((1) Université Paris-Saclay CEA Service de Recherches en Corrosion et Comportement des Matériaux SRMP, (2) PIMM Arts et métiers Institute of Technology CNRS CNAM HESAM University)
Polymers are widely used as functional insulating materials, but predicting their dielectric behavior is challenging because multiple mechanisms, acting across different spatial and temporal scales, contribute to their response. In polyethylene (PE), one of the most common polymers, electronic, atomic, and mesoscale dynamics must all be considered.
In this work, semicrystalline models of polyethylene were developed and investigated using a multiscale approach. Quantum simulations were employed to describe electronic and vibrational contributions to the dielectric response, while classical molecular dynamics simulations captured the behavior of polymer chains at room temperature and frequencies down to the 10-100 MHz range.
The study focuses on the impact of radio-oxidation defects on the dielectric properties of polyethylene. Quantum calculations reveal how electronic and vibrational contributions depend on the local atomic environment surrounding these defects. Comparison with molecular dynamics results highlights the influence of temperature on the static dielectric constant. Structural analyses further assess the effect of each defect type on PE crystallinity.
Analysis of dipolar correlation functions shows that different defects interact with one another and with the polymer matrix in distinct ways, affecting permittivity and dielectric loss peaks. For all defect types, defect-defect interactions provide the largest contribution to dielectric response. While most oxidized groups exhibit positive coupling with the PE matrix, alcohol defects display a negative cross-correlation, partially offsetting their impact on the dielectric properties.
Our results also show that ketone groups produce the largest dielectric loss between the defects studied.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph), Computational Physics (physics.comp-ph)
36 pages, 11 figures
High-throughput computational discovery of CuI-based ternary $p$-type transparent conductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Michael Seifert, Miguel A. L. Marques, Silvana Botti
P-type transparent conducting materials (TCMs) remain scarce, limiting progress in transparent electronics and tandem photovoltaics. Here, we perform a high-throughput computational search across CuI-based ternary X–Cu–I compounds using the minima hopping method combined with density functional theory. Filtering for thermodynamic stability, optical transparency, and light hole effective mass, we identify 58 candidate p-type TCMs, of which 49 are previously unreported. Twenty are p-type degenerate semiconductors with intrinsic hole carriers, including Cu$ _2$ FI$ _2$ (calculated gap 3.75 eV, hole effective mass $ 0.262,m_0$ ). We further use this dataset to revisit the chemical modulation of the valence band (CMVB) design rules, originally formulated for Cu-based delafossite oxides. Four generalizations emerge: linear Cu coordination is not required, as tetrahedral coordination (CN = 4) is compatible with p-type TCM character; the mechanism extends to halide-based systems with I $ 5p$ anion states; the Cu $ d$ state energy center $ \epsilon_d$ is a quantitative descriptor for valence band dispersion; and Cu undercoordination in monovalent-anion hosts drives intrinsic p-type carrier generation through stoichiometric charge balance. These results establish a generalized computational framework for the design of p-type halide TCMs.
Materials Science (cond-mat.mtrl-sci)
Criticality enabled long-range order in a U(1)-symmetric spin-1 Heisenberg chain with biquadratic interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Natalia Chepiga, Fabian H.L. Essler
In a recent paper Nahum argued on the basis of a renormalization-group analysis that, contrary to standard lore, ground states of 1D spin chains with short-range interactions can spontaneously break U(1) ``easy-plane’’ spin rotation symmetry. True long-range order of $ (S^x,S^y)$ arises at the phase transition between two quasi-long-range-ordered phases. Here we present detailed numerical results for an anisotropic spin-1 chain model. We find a magnetization exponent $ \beta\approx0.29$ , consistent with the $ \epsilon$ -expansion prediction $ \beta\approx0.28$ , a divergence of the Luttinger parameter on approaching the transition from both sides with an exponent that we relate to Nahum’s transition, and finite-size spectra consistent with a dynamical critical exponent $ z\approx2$ . Our results support the critical behavior predicted by Nahum’s field theory.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
21 pages, 16 figures
The memory equation of a characteristic function in surface diffusion: a sum rule
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
The decay of a density wave in an interacting adlayer obeys an exact memory equation of Mori’s form. Being a Fourier component of a conserved density, its correlation function is a characteristic function, and the kernel is built from a second one, that of a single jump. The local rate obeys a sum rule whose momentum dependence is one minus the characteristic function of a single jump, divided by the static structure factor. Detailed balance makes the decay a superposition of relaxation modes of non-negative weight whose moments are static equilibrium averages, so that the truncations of the associated continued fraction form a convergent hierarchy of closed forms, each of them a bound on the decay itself. The single rate a fit returns is shown to be the mean of the instantaneous rate over a time window, hence never above the local rate. At long wavelength, the two coincide, the relaxation spectrum separating there, one collective mode taking almost the whole weight of the density wave and the single exponential usually fitted to spin-echo data being the decay itself. What an experiment reaches at every wavevector is also the area under the decay, a correlation time. Together with the static structure factor and the single-jump geometry, it forms one combination which the theory identifies with the effective hop rate divided by the product of the local rate and the correlation time. That product never falls below unity and tends to unity at long wavelength whenever the rate at which an adparticle leaves a site is independent of the site it leaves for. In the hydrodynamic limit, the sum rule becomes a relation of Darken type in which the rate multiplied by the thermodynamic factor is the effective hop rate and not the mobility of a labelled adparticle.
Statistical Mechanics (cond-mat.stat-mech)
20 pages; 1 figure; 1 table
A quantitative phase-field model for grain boundary trapping and diffusion of hydrogen
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Vincent Feyen, Martin Diehl, Nele Moelans
Grain boundaries influence hydrogen transport in polycrystalline metals by acting as both trapping sites and interconnected diffusion pathways. Conventional interpretations of thermal desorption spectroscopy (TDS) and permeation experiments often treat traps as isolated defects, neglecting grain boundary connectivity and potentially misinterpreting experimental data. Here, we develop a quantitative phase-field model for hydrogen diffusion, grain boundary trapping, and grain boundary-assisted transport. The formulation preserves the physical grain boundary volume independently of the numerical interface thickness and accounts for anisotropic diffusion parallel and perpendicular to grain boundaries. Benchmark simulations verify quantitative behavior under interface upscaling. The model shows that grain boundary diffusion can significantly shift TDS peaks, making Kissinger-type analyses unreliable when grain boundary transport is significant. Effective diffusion coefficients are also shown to depend strongly on grain size, trapping free energy, temperature, and grain boundary mobility. These results highlight the coupled role of trapping thermodynamics, bulk diffusion, and grain-boundary transport.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Polar discontinuity screening by charge disproportionation in ferroelectric-nickelate superlattices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Edith Simmen, Jonathan Amara, Philippe Ghosez, Nicola A. Spaldin
We use density functional theory (DFT) to demonstrate rearrangement of charge disproportionation as a new mechanism for screening polar discontinuities at heterointerfaces. We focus on SmNiO$ _3$ , a III-III perovskite characterized by an insulating ground state that originates from disproportionation of the electrons at the Ni sites. When interfaced with ferroelectric, II-IV perovskite BaTiO$ _3$ , this system can display a polar discontinuity whose magnitude is determined by the nature of the interface (NiO$ _2$ -BaO or SmO-TiO$ _2$ ) and the orientation of the BaTiO$ _3$ spontaneous polarization. In the orientation maximizing the interface charge, SmNiO$ _3$ compensates by transferring 1 $ e$ /f.u. between the two interfaces and modifying the disproportionation sequence from Ni$ ^{4+}$ /Ni$ ^{2+}$ to Ni$ ^{2+}$ /Ni$ ^{2+}$ at the SmO-TiO$ _2$ interface and to Ni$ ^{4+}$ /Ni$ ^{4+}$ at the NiO$ _2$ -BaO interface. While this mechanism is potentially universal in all perovskites exhibiting charge disproportionation, our formal analysis of BiNiO$ _3$ /BaTiO$ _3$ superlattices suggests that larger polar discontinuities may need more complex disproportionation patterns for screening.
Materials Science (cond-mat.mtrl-sci)
Non-Uniform Quantum Well and Barrier Thickness Engineering for Robust Ultra-High TER and Low RA Ferroelectric Tunnel Junctions
New Submission | Other Condensed Matter (cond-mat.other) | 2026-09-28 20:00 EDT
Balram Khattar, Adarsh Tripathi, Manish Anand, Abhishek Sharma
HfO$ _2$ -based ferroelectric tunnel junctions (FTJs) are promising candidates for scalable non-volatile memory, but simultaneously achieving a high tunneling electro-resistance ratio (TER) and a low resistance-area (RA) product remains challenging. To address this challenge, this work introduces non-uniform quantum well (QW) and barrier thickness engineering in HfO$ _2$ -based multi-QW FTJs using a self-consistent Preisach-based ferroelectric (FE) model integrated with the coherent and inelastic non-equilibrium Green’s function (NEGF) formalism. The non-uniform well and barrier configuration produces a wide range of FTJ design landscapes due to closely spaced, broad resonant states in the low resistance state (LRS) and a larger separation in the high resistance state (HRS), resulting in strong polarization-dependent resonant transmission with TER reaching the order of $ \mathbf{1\times10^{8}%}$ and an LRS RA product as low as $ \mathbf{1~\Omega\cdot\mathrm{cm}^{2}}$ at read bias and in the presence of scattering. By incorporating self-consistent elastic scattering into the NEGF framework, we also show that elastic scattering can positively influence the TER and RA performance of non-uniform FTJs by progressively increasing the overlap of the closely spaced resonances. Overall, the results establish non-uniform QW and barrier thickness as an effective and robust design parameter for controlling resonant-state alignment and achieving a favorable combination of high TER and low RA in HfO$ _2$ -based multi-QW FTJs.
Other Condensed Matter (cond-mat.other)
7 pages, 10 figures, journal
Dielectric response of the antiferromagnetic multiferroics with cycloidal equilibrium for the polarization related to the noncollinear spins
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Linear dynamics of the small amplitude perturbations in the antiferromagnetic multiferroics is analytically considered. Equilibrium state in the considered regime is assumed to be cycloidal structure both for the antiferromagnetic vector and the nonzero magnetization vector (presence of weak ferromagnetism in the system is included). The electric polarization of spin origin related to the “noncollinear” spins is considered and its influence on the spin dynamics is included. The dynamical electric susceptibility tensor is obtained to demonstrate response of the multiferroics on the alternating electric field. Existence of two polarization projections is found, response of each of them on two projections of the electric field perpendicular to the cycloid direction is presented. Different roles of the in plane and out of plane electric perturbations is demonstrated analytically. Essential role of the low frequency gapless spin wave in the dielectric response is described. Contributions of the spiral structure and the weak ferromagnetism in the dielectric response are specified.
Materials Science (cond-mat.mtrl-sci)
6 pages, 1 figure
Maximal Chern Numbers from Finite-Range Hopping
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Christopher Arriagada Cortés, Vladimir Juričić
Finite-range hopping constrains both the number of Dirac points and the masses that gap them. We determine the maximal absolute Chern numbers of an isotropic finite-range extension of the Qi–Wu–Zhang model on a square lattice through thirteenth-neighbor hopping. Algebraic zero counting and mass-weighted sum rules yield global bounds, and we construct explicit Hamiltonians that saturate them. We find $ |C|_{\max}=36,40,51$ for eleventh-, twelfth-, and thirteenth-neighbor hopping. Equal numbers of Dirac points can produce different maxima because finite-range mass harmonics distinguish opposite vortex charges differently. Twice the squared hopping radius bounds every maximum through twelfth-neighbor hopping and is saturated at the eleventh and twelfth, but the thirteenth-neighbor maximum exceeds it. Thus finite-range hopping constrains the maximal Chern number in two complementary ways: through the number of Dirac vortices it can generate and through the mass-sign patterns it can assign to them. This geometric viewpoint provides a design principle for high-Chern bands and a route to analogous bounds in moiré and other lattice systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 2 figures, SM as ancillary file
Spatiotemporal Non-Hermitian Skin Effect with Floquet-Engineered Ultracold Atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-09-28 20:00 EDT
Weijie Liang, Weiping Zhang, Keye Zhang
Non-Hermitian skin effect, the accumulation of bulk eigenstates at edges under open boundary conditions, has been observed across classical, quantum, and synthetic platforms. Whether it can be generalized to the genuine time dimension remains open. We propose a spatiotemporal NHSE in the Floquet phase space via Floquet engineering of a ring-trapped ultracold atomic gas. Placing spatial and temporal degrees of freedom on an equal footing, we show that a single parent skin effect projects onto either domain. The spatial projection yields an NHSE with arbitrarily tunable skin locations, eliminating the need for physical open boundaries. The temporal projection gives time-domain nonreciprocity and periodic temporal funneling, consistent with causality. This establishes a unified spatiotemporal paradigm for NHSE and opens a route to non-Hermitian topological physics in time.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Ferroelectric Switching in ZnO/Zn1-xMgxO Heterostructures: Atomistic Insights into Interfacial Coupling and Layer Architecture
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Alireza Sepehrinezhad, Ali Mohammadi Dinani, Ece Gunay, Elizabeth C. Dickey, Jon-Paul Maria, Susan Trolier-McKinstry, Adri C.T. van Duin
Ferroelectric switching in heterostructures couples composition, layer topology, temperature, and interfacial boundary conditions. ReaxFF molecular dynamics isolates these variables in ZnO/ Zn1- xMgxO/ZnO and Zn1-xMgxO/ZnO/ Zn1-xMgxO stacks. Within pristine, initially single-domain models, coupling to switchable Zn1-xMgxO reduces the applied field required to reverse ZnO by up to fivefold. Temperature generally lowers the coercive field, whereas Mg concentration produces a nonmonotonic response. At equal ZnO and Zn1-xMgxO (ZMO) proportions, structures with ZnO at the center switch at lower fields than those with ZMO at the center at all four temperatures examined, demonstrating a topology-dependent response. Layer-resolved trajectories reveal topology-dependent switching sequences with direction-dependent redistribution of normal stress near the heterointerfaces, consistent with a stress-assisted cooperative pathway. Limiting MgO-containing structures exhibit sequential multilevel switching or low-polarity trapping, depending on thickness and temperature. Fixed-charge atomistic simulations complement previous continuum descriptions by resolving structural, energetic, and local stress evolution under a common applied field. TEM and STEM-EDS observations provide experimental structural context for the modeled architectures. Together, the results establish layer topology and interfacial mechanical confinement as design variables for wurtzite ferroelectric heterostructures.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Crystallographic-orientation dependence of the early-stage oxidation of Zr single crystals: an XPS study of suboxide formation and in-depth distribution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Joaquin Sacanell, Flavio Conde
The influence of crystallographic orientation on the early stages of the oxidation of pure Zr single crystals was studied by X ray photoelectron spectroscopy (XPS). Two samples, cut from the same a-Zr single crystal, were oxidized simultaneously at room temperature and O2 pressures of 1 X 10-8, 1 X 10-7 and 1 X 10-6 torr: one with its surface normal parallel to the c-axis (Z1, basal (0001) plane) and the other with its normal 12deg from that of a prismatic plane (Z2, near-prismatic orientation). At all three pressures the oxidation kinetics of both samples followed a three stage, logarithmic type behaviour, but the near prismatic sample (Z2) incorporated oxygen faster and to a greater extent than the basal sample (Z1) in every case. Deconvolution of the Zr 3d core level spectra resolved, in addition to metallic Zr and ZrO2, two sub-stoichiometric Zr O compounds, denoted (ZrO)a and (ZrO)b, with binding-energy shifts of 1.3 and 2.3 eV with respect to metallic Zr, consistent with sub oxides previously reported for polycrystalline Zr. Angle resolved XPS showed that ZrO2 is the outermost compound in both orientations, while the two sub-oxides are distributed nearly homogeneously through the film. Oxide thicknesses, calculated from the attenuation of the metallic Zr 3d signal, ranged from 10 to 13 A for Z1 and from 14 to 19 A for Z2 depending on the oxidation pressure, in close agreement with earlier measurements on cold worked polycrystalline Zr, whose surface texture is dominated by prismatic-oriented grains.
Materials Science (cond-mat.mtrl-sci)
13 pages, 5 figures, Submitted to Journal of Nuclear Materials
Rydberg excitons in core-shell nanostructures II. Plasmon-exciton interaction and enhancement
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
David Ziemkiewicz, Gerard Czajkowski, Sylwia Zielińska-Raczyńska
Interaction between Rydberg excitons in core-shell Cu$ _2$ O nanostructures and surface plasmons is investigated. An enhancement of a quadrupole transitions to the Rydberg exciton states in copper oxide plasmonic nanaostructures is examined. A possibility of a modification of plasmonic enhancment (i.e., an average amplification factor) of electric field distributions in the vicinity of nanostructures, which depends on its shape and geometrical size, is also discussed.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
12 pages, 11 figures
Retrainable physics-integrated neural differentiable modeling of sintering across material systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Zeping Chen, Ani Aprahamian, Khachatur V. Manukyan, Tengfei Luo
Sintering is widely used to manufacture ceramics, but coupled densification and grain growth, material-dependent kinetics, and sparse measurements complicate predictive modeling and process design. We present Sinter-PiNDiff, a retrainable physics-integrated neural differentiable framework for predicting density and grain-size evolution. Two neural networks learn densification and grain-growth coefficients within coupled rate equations, while a smooth saturation factor attenuates densification near theoretical density. The same governing structure, network architecture, and training procedure were fitted independently to published data for MgO, Al-doped ZnO, and CaO-doped ThO2. Tests at held-out temperatures and compositions yielded the lowest mean error in all twelve material-metric comparisons against multilayer perceptron and residual network baselines. For MgO, Al-doped ZnO, and CaO-doped ThO2, respectively, density normalized root-mean-square errors were 14.6%, 10.8%, and 14.4%, and grain-size errors using the same metric were 8.6%, 12.1%, and 19.3%. Removing evolving density from both neural-network inputs increased density and grain-size trajectory errors in all three systems and ten of twelve aggregate errors, supporting density-dependent kinetic feedback. Deep ensembles estimated model disagreement, but empirical coverage showed that the uncertainty bands were not calibrated and did not capture all model-data discrepancies. These results establish Sinter-PiNDiff as a retrainable framework for sparse-data prediction and uncertainty-informed selection of sintering conditions.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Complexity drives the symmetry breaking of temperature fluctuations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-09-28 20:00 EDT
D. Rosales Herrera, M. Y. Gallegos Ruiz, A. Fernández Téllez, J. R. Alvarado García, J. E. Ramírez
Frequently, nonextensive systems are described through $ q$ -exponential functions, where the $ q$ -parameter determines how far a system is from equilibrium. In this work, we study systems constrained to $ q-1\ll1$ to describe systems near thermal equilibrium, and derive the probability density function and temperature fluctuations. To this end, we derive the series expansion of the $ q$ -exponential function, yielding a perturbative series that is a superposition of gamma distributions. On the other hand, the temperature fluctuations are expressed as a superposition of Dirac delta functions and their derivatives, meaning that the bulk of the system remains at a constant temperature, while point-temperature variations emerge, marking the system’s departure from thermal equilibrium. The statistics of the temperature fluctuations exhibit a transition from a symmetric to a nonsymmetric distribution as the nonextensive parameter increases. These results provide evidence of the association between the emergence of nonextensivity and the symmetry breaking of temperature fluctuations.
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 5 figures. Accepted for publication in Physical Review E
Structural prediction of B${18}$Y${2}$ cluster: A Machine-Learning-Assisted Basin-Hopping Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Peter Ludwig Rodríguez-Kessler
The structural and optical properties of the doubly yttrium-doped boron cluster B$ _{18}$ Y$ _2$ have been systematically investigated using density functional theory calculations. The lowest-energy structure was identified through extensive basin-hopping searches accelerated by a pre-trained MACE machine-learning potential and subsequently refined and validated at the DFT level. The resulting global-minimum structure adopts a double-ring geometry, consisting of two fused B$ _9$ rings stabilized by yttrium atoms positioned above and below the boron framework. Vibrational frequency calculations confirm the dynamical stability of the optimized structure, while the calculated infrared and UV–Vis spectra provide characteristic signatures of the Y–B interactions and the electronic structure of the boron framework. These results demonstrate how yttrium doping can stabilize unusual double-ring boron architectures and highlight the effectiveness of machine-learning-assisted basin-hopping searches for exploring the complex potential-energy landscapes of doped boron clusters.
Materials Science (cond-mat.mtrl-sci)
5 pages, 4 figures
Unconventional magnetoelastic behavior in Al rich CoFeAl Films with inverse Heusler like local order for flexible spintronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-09-28 20:00 EDT
Rupalipriyadarsini Chhatoi (1 and 2), Anuroopa Behatha (3), Swayang Priya Mahanta (1 and 2), Shubhransu Sahoo (1 and 2), Soubhagya Dash (1 and 2), Bhuvneshwari Sharma (1 and 2), Abhisek Mishra (1 and 2)Esita Pandey (1 and 2), Satadeep Bhattacharjee (3), Subhankar Bedanta (1,2 and 4) ((1) Laboratory for Nanomagnetism and Magnetic Materials (LNMM), School of Physical Sciences, National Institute of Science Education and Research (NISER), Jatni, Odisha, India (2) Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, India (3) Indo Korea Science and Technology Center (IKST), Bangalore, India (4) Center for Interdisciplinary Sciences (CIS), National Institute of Science Education and Research (NISER))
Strain engineering of magnetic properties offers a promising route toward flexible spintronic applications. Here, we report an unconventional magnetoelastic response in Al rich Co Fe Al thin films on flexible substrates using strain dependent magneto optical Kerr effect microscopy and magnetometry measurements. While the films exhibit a conventional positive magnetostriction coefficient, consistent with standard in plane easy axis rotation under stress, their saturation magnetization increases under compressive strain and decreases under tensile strain. First principles calculations reveal that this unconventional response originates from a strain induced competition between exchange splitting and crystal field effects in an inverse Heusler like local environment created by Al enrichment. This leads to a highly sensitive, sublattice dependent magnetic state, consistent with a strain induced reconfiguration of Co and Fe moments. Our results demonstrate that local compositional tuning can fundamentally alter magnetoelastic behavior, establishing strain controlled sublattice compensation as a route toward programmable magnetic functionality in flexible spintronic systems.
Materials Science (cond-mat.mtrl-sci)
7 Pages, 5 figures
Emergent frustrated magnetism in strain-patterned graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-09-28 20:00 EDT
Yu-Chiang Hsieh, Wen-Han Kao, Christophe De Beule, Sheng-Zhu Ho, Ru-Long Gou, Bo-Nian Chen, Kuan-Yu Chou, Kuo-En Chang, Chin-Chia Chang, Ying-Mei Yang, Ching-Hua Kao, Hao-Chien Chiang, Jyun-Lin Chen, Sheng-Chin Ho, Kenji Watanabe, Takashi Taniguchi, Ming-Hao Liu, Ching-Hao Chang, Yi-Chun Chen, Ying-Jer Kao, Tse-Ming Chen
Geometrically frustrated magnetism conventionally arises from pre-existing magnetic moments on lattices whose geometry prevents their interactions from being simultaneously satisfied, giving rise to highly degenerate states and rich collective behavior. Creating such frustration in an intrinsically non-magnetic material presents a fundamentally different challenge, requiring both the magnetism and the competing interactions to emerge from correlated electrons. Here we show that this can be realized in graphene through lithographically programmable strain engineering. Patterning strain and the associated pseudo-magnetic field (PMF) into superlattices creates a correlated electronic system with flat bands and strong interactions. Transport measurements reveal interaction-driven insulating behavior, anisotropic magnetic hysteresis, and slow relaxation dynamics reminiscent of spin freezing, qualitatively captured by Monte Carlo simulations of competing magnetic moments on the PMF-defined ruby superlattice. Cryogenic magnetic force microscopy further reveals magnetic textures associated with the PMF landscape. These observations demonstrate frustrated magnetism emerging from correlated electrons in otherwise non-magnetic graphene. Our results establish lithographic strain engineering as a general and scalable route to flat bands and correlated states in van der Waals materials, providing a versatile platform for programmable quantum matter.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
56 pages (including supplementary information)
A Unified Spin-Fermion Framework for Magnetic Diversity in Chromium Monopnictides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Ruoshi Jiang, Bartomeu Monserrat
Isoelectronic compounds are generally expected to exhibit related electronic, structural, and magnetic behavior. Chromium monopnictides CrX (X= Sb, As, P), however, display a striking evolution from high-temperature altermagnetism in NiAs-type CrSb, through double-helical antiferromagnetism in MnP-type CrAs, to the absence of resolved long-range magnetic order in MnP-type CrP. Here, combining first-principles calculations in the non-collinear Curie-paramagnetic state, structural analysis, magnetic phase-diagram calculations, and exchange-parameter extraction, we establish a unified microscopic framework for this evolution. All three compounds share a formal high-spin $ d^5$ configuration, nominally Cr$ ^{1+}$ , coupled to itinerant states of predominantly pnictogen character. From Sb to P, chemical pressure enhances ligand itinerancy and drives the structural evolution from the high-symmetry NiAs lattice to increasingly distorted MnP-type networks. The accompanying reconstruction of competing Cr-Cr exchanges favors A-type antiferromagnetism in CrSb and double-helical order in CrAs, while placing CrP near a frustrated regime with closely competing magnetic tendencies. Our results establish chemical-pressure-driven exchange reconstruction as a general mechanism through which a common spin-fermion electronic structure can generate contrasting magnetic phases in strongly correlated materials.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
7 pages, 2 figures, 2 tables
Quantum Representation Selects Neutral Skyrmion Molecules
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-09-28 20:00 EDT
Skyrmions experience a sideways gyroscopic force when they move. Bound molecules can cancel this force; we call them gyroscopically neutral. We show that the quantum states available on each site of a magnet select the composition needed for cancellation. In two models of $ SU(3)$ magnetism, this composition changes from a pair to a trimer. Both models assign exactly the same energy to every configuration of their common classical order parameter, isolating the effect of the local quantum states. Neutral molecules can also unwind when additional local states are allowed. Mean field calculations nevertheless find both compositions bound and locally stable, with the neutral trimer surviving sampled interaction changes. Comparing their motion reveals the changed cancellation rule, and prepared neutral molecules translate over short distances with little deformation.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th), Pattern Formation and Solitons (nlin.PS)
5 pages, 3 figures + supplement; code and data available on Zenodo
Research Square
MetaLFM: Metalens-array-enabled High-Density Optical Sampling for High-Resolution Volumetric Bioimaging by Light Field Microscopy
Article | Nanophotonics and plasmonics | 2026-09-27 20:00 EDT
Euiheon Chung, Tien Nhat Nguyen, Doyoon Lee, Huu Lam Phan, Akm Ashiquzzaman, Yesl Jun, Minkyung Kim
Light field microscopy enables snapshot volumetric imaging by simultaneously capturing spatial and angular information. However, its imaging performance is fundamentally governed by the sampling geometry of the microlens array. Increasing the sampling density through reduced lens pitch is desirable for improving spatial resolution yet implementing small-pitch refractive microlens arrays while maintaining the focal length and f-number required for LFM becomes increasingly challenging because of geometric fabrication constraints. Here, we present MetaLFM, a metalens-array-enabled high-density optical sampling architecture for high-resolution volumetric bioimaging. A large-area TiO2 metalens array with a 75-µm pitch and a designed focal length of 1430 µm was engineered to provide reduced-pitch sampling while maintaining the f-number matching condition required for light field acquisition. Experimental characterization demonstrated consistent focusing performance across the fabricated array and confirmed a stable operating condition for spatial-angular light-field sampling. Compared with conventional LFM using a 100-µm-pitch refractive microlens array, MetaLFM reduced the reconstructed lateral and axial full width at half maximum by up to 44% and 39%, respectively, across the evaluated imaging depth, while reducing grid-like reconstruction artifacts near the native image plane. Volumetric imaging of mouse spinal cord tissue and human intestinal organoids showed improved structural delineation and reconstruction fidelity, while 25 Hz calcium imaging of primary cortical neurons demonstrated applicability to dynamic bioimaging. These results expand the resolution-depth capabilities of light field microscopy for high-resolution volumetric bioimaging.
Research Square:rs-10896258 (2026)
Posted on Research Square and Under Review at Microsystems & Nanoengineering
Physical sciences/Optics and photonics/Optical physics/Nanophotonics and plasmonics, Physical sciences/Optics and photonics/Other photonics/Micro-optics
Ultrafast Dynamics of Pressure‑Activated Energy Funneling and Amplified Spontaneous Emission in Microscale Quasi-2D Perovskites
Article | Ultrafast photonics | 2026-09-27 20:00 EDT
Dingke Zhang, Shuaiqi Li, Linrui Li, Haiyang Hu, Xing Tang, Mingyu Pi, Yexiong Huang, Jingwen Yao, Haiyang Xu, Laizhi Sui, Qing Zhang, Zhenxiang Chen
Quasi-2D perovskites are attractive for optical gain because of their large exciton binding energies, built-in quantum wells, and efficient energy funneling. However, for micro- and nanolasers, these same properties create a fundamental problem: the energy funnel relies on a statistical mix of different phases, and miniaturize the device inevitably disrupts this delicate distribution–causing the optical gain to collapse. Here we show that high-pressure engineering, a clean and controllable approach, breaks this size-imposed limitation. Applying hydrostatic pressure to microscale (PEA)2FAn-1PbnBr3n+1 films rebuilds efficient energy funneling in microscale (PEA)2FAn-1PbnBr3n+1 perovskites, activating amplified spontaneous emission (ASE) that is otherwise absent. A modest 0.14 GPa turns on ASE, and at 0.41 GPa the ASE threshold drops by 50%. In situ structural and femtosecond transient absorption measurements reveal a two-step compression-mode transition that directly resolves accelerates energy transfer from low-n to high-n phases and extends the high-n carrier lifetime by 60%. This work uncovers the ultrafast dynamics and photophysical mechanism behind pressure-tuned energy transfer and opens a new route to chip-scale coherent light sources from quasi 2D perovskite film, with direct implications for ultrafast nonlinear optical probes of quantum materials.
Research Square:rs-11050430 (2026)
Posted on Research Square and Under Review at Light: Science & Applications
Physical sciences/Physics/Optical physics/Ultrafast photonics, Physical sciences/Optics and photonics/Optical physics/Micro-optics