Materials Science
Detection of acoustic phonons in carbon by Raman spectroscopy
Konstantin Iakoubovskii, Andrey Katrusha, Weihua Peng et al. (+1 more)
We detected acoustic
phonons in graphite and diamond by Raman spectroscopy supported by density functional theory calculations. The activation of these normally forbidden Raman modes was achieved via
lattice amorphization in case of graphite and by boron doping in case of diamond. The doping-induced Raman signal in diamond was identified with substitutional boron of tetrahedral
symmetry via its dependences on excitation wavelength and polarization. Comparison of the Raman spectra of amorphized graphite and heavily boron-doped diamond suggests the emergence of graphitic-like disorder in the diamond
lattice. The reported approach is not limited to carbon and can be extended to a wide range of other materials.
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All authors Konstantin Iakoubovskii, Andrey Katrusha, Weihua Peng, Jianguo Peng
Materials Science
Temperature-Driven Sequential Modeling for the Prediction of Annual Power Conversion Efficiency Profiles of Organic Photovoltaic Materials: Douala Case Study
Steve Cabrel Teguia Kouam, Rockefeller Rockefeller, Raoult Dabou Teukam et al. (+4 more)
Organic photovoltaic (OPV) materials are promising candidates for distributed
solar energy in tropical regions, yet existing virtual screening tools report static power conversion efficiency (PCE) values at standard testing conditions (STC) that fail to capture the temperature-driven performance degradation experienced under real deployment conditions. Here we introduce a
Climate-Native computational framework that forecasts the annual PCE profile of OPV donor molecules under geographically realistic operating conditions. The framework combines GFN2-xTB molecular dynamics with an equivariant graph neural network surrogate ($268$ Neyman-stratified CEP molecules; $120,600$ training geometries; $\sim 1050\times$ speedup over explicit
quantum chemistry) and sequential deep learning models trained on annual time series anchored in NASA POWER
climate data for Douala, Cameroon, and validated by zero-shot transfer to Yaoundé and Maroua. Applied to $\sim 30,000$ molecules from the Harvard Clean Energy Project (CEP) and validated against $350$ HOPV15 experimental device measurements, the framework demonstrates that sequential models trained on full molecular dynamics trajectories outperform time-averaged baselines ($35\%$-$48\%$ relative MAE improvement over static baselines), confirming that thermal conformational dynamics carry information beyond mean geometry. We further introduce a seasonal stability score that reranks OPV candidates by performance consistency under tropical conditions, identifying molecules whose deployment suitability differs substantially from their static PCE ranking.
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All authors Steve Cabrel Teguia Kouam, Rockefeller Rockefeller, Raoult Dabou Teukam, Jean-Pierre Tchapet Njafa, Patrick Sorrel Mvoto Kongo, Jean-Pierre Nguenang, Serge Guy Nana Engo
Strongly Correlated Electrons
Nonequilibrium dynamics of doped Chern ferromagnets: a case study for false vacuum decay
Kilian Kuhlbrodt, Olivier Huber, Oliver Breach et al. (+7 more)
Even though metastable false
vacuum decay is ubiquitous in physics, its underlying dynamics are still not well understood. Dissipative state preparation in moiré
quantum materials provides an exceptional setting for exploring this physics since it allows the possibility of generating exotic
quantum states that are not the ground state of the system
Hamiltonian. Motivated by recent experiments demonstrating steady-state optical orientation of the
spin-valley degree of freedom of holes, here we investigate dynamics of itinerant and Chern ferromagnets in the presence of an opposing
magnetic field. Optical pumping using a circularly polarized Laguerre-Gauss beam allows us to deterministically prepare a true
vacuum bubble embedded inside a metastable state. Depending on its initial size controlled by the pump power, we observe that the bubble collapses or expands due to an interplay between domain wall and bulk dynamics. For external
magnetic fields comparable to the coercive field of ferromagnetism, we observe up to two-orders-of-magnitude prolongation of the
spin polarization decay time at commensurate fillings corresponding to integer and fractional Chern
insulator states. Our experiments reveal that the nonequilibrium dynamics of the
ferromagnetic domains is substantially more sensitive to the precise filling factor around Chern
insulator states than standard transport or optical measurements.
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All authors Kilian Kuhlbrodt, Olivier Huber, Oliver Breach, Weijie Li, Xiaodong Xu, Kenji Watanabe, Takashi Taniguchi, Martin Kroner, Siddharth A. Parameswaran, Atac Imamoglu
Mesoscale and Nanoscale Physics
Rajveer Fandan and Jorge Pedrós
Polaritons formed by strong coupling between
excitons and confined electromagnetic modes underpin emerging nanophotonic technologies, yet platforms based on isotropic metals or optical microcavities provide limited control over propagation direction. Here we predict that monolayer MoS$_2$ on the in-plane
hyperbolic conductor MoOCl$_2$ supports
hyperbolic exciton-plasmon polaritons governed by crystallographic direction, slab thickness, and
hyperbolic mode order. Using an anisotropic transfer-
matrix model coupled to a dissipative three-level
Hamiltonian, we obtain wavevector-dependent anticrossings between the MoOCl$_2$ plasmons and the
spin-orbit-split A and B
excitons of MoS$_2$, yielding lower, middle, and upper polariton branches with coupling energies $g_A$ = 64.7 meV and $g_B$ = 61.2 meV. Rotating the in-plane wavevector tunes the plasmon-
exciton detuning, while increasing the MoOCl$_2$ thickness activates higher-order
hyperbolic Fabry-Pérot modes. Their coupling follows an approximate effective-mode-volume scaling. Strong coupling persists for excitonic linewidths up to 50 meV, with the normalised spectral-resolution ratio remaining above unity. These results establish MoS$_2$/MoOCl$_2$ as a lithography-free platform for directional and multimode
exciton-plasmon polariton engineering in the visible spectral range.
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Disordered Systems and Neural Networks
Clustered Attractor Manifolds and Dynamical Condensation in Self-Attention
Qucheng Gao, Zuyi Yang and Xiao Chen
Transformer layers generate state-dependent interaction networks:
token representations determine the
attention matrix, which in turn updates the representations. We study this feedback in a minimal normalized self-
attention dynamics and identify the overlap gap as the central quantity governing its attractor structure in the thermodynamic limit. When
tokens form internally aligned clusters and their similarity to members of the same cluster exceeds that to every other cluster by a nonvanishing amount, inter-cluster
attention is exponentially suppressed as the dimension increases. This mechanism produces a high-dimensional
manifold of clustered fixed points, ranging from a few macroscopic clusters to extensive microscopic fragmentation, and also controls their stability against perturbations. Starting from an unstructured Gaussian state, we find that clustered states nucleate from the diffuse background only above a finite threshold in
attention sharpness, giving rise to a dynamical
attention-condensation transition.
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Mesoscale and Nanoscale Physics
Relaxation-driven flat bands and topology in moiré transition metal dichalcogenide heterobilayers
Mitchell Luskin, Max Geier, Liang Fu et al. (+1 more)
Moiré transition metal dichalcogenide (TMD) heterobilayers are commonly modeled by a continuum theory that yields topologically trivial bands, in contrast to their homobilayer counterparts which host topological bands and fractional Chern
insulators (FCI). We show this conclusion is an artifact of neglecting the pseudomagnetic field generated by
lattice relaxation, an effect intrinsic to every moiré material. We develop a continuum model that resolves relaxation into three channels: a modified moiré potential with higher
Fourier harmonics, a pseudoelectric (scalar deformation) potential, and a pseudomagnetic (vector) potential. Using WSe$_2$/WS$_2$ as a prototype, we find that the pseudomagnetic field alone gaps the third and fourth valence bands with Chern numbers $\pm 1$ over a broad range of twist angle and
lattice mismatch, while the moiré potential correction and pseudoelectric potential narrow the bandwidth and enhance the bandgaps, which survive many-body interactions using neural-network variational Monte Carlo calculations. Relaxation also smoothens the Berry
curvature and
quantum metric relative to the rigid model, moving the band closer to the ideal Chern limit, beneficial for the
quantum anomalous
Hall effect, FCI states, and flat-band superconductivity when filled to higher bands. Our work establishes a new framework that connects first-principles calculations, through the continuum model, to many-body observables. Using this framework, we show moiré heterobilayers as a new class of topological materials whose
topology is driven entirely by intrinsic
lattice relaxation.
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All authors Mitchell Luskin, Max Geier, Liang Fu, Ziyan Zhu
Materials Science · Cross-listed from physics.optics
Nonresonant optomechanical control of structural phases
Jiaojian Shi, Yijing Huang, Christian Heide et al. (+24 more)
Optical tweezers demonstrate how light can exert forces to trap, repel, and manipulate microscopic particles without absorption. Recent theory has suggested that such forces can extend beyond particle manipulation to drive structural phase transitions in solids. Here we apply this optomechanical principle to tin selenide (SnSe), a material where proximity to several different structural phases gives rise to its high thermoelectric figure of merit and makes it a candidate for a switchable topological crystalline
insulator. Whereas the force for standard optical tweezers arises from a gradient in the intensity of a light field, the optomechanical force is mediated by a gradient in the dielectric constant as a function of
phonon coordinate. Unlike conventional methods that rely on resonant excitation and absorption through the imaginary part of the dielectric function, this approach operates dispersively through the real part and can be directly driven by Raman processes, enabling selective transitions with reduced energy cost and ultrafast response. Using time-domain Raman scattering, we show that above a critical mid-infrared field strength the $A_g$ Raman modes disappear abruptly without softening, signaling the formation of a new structural phase. This phase, distinct from those induced by heating or carrier excitation, exhibits large-amplitude and long-lived modulations in its optical response. Complementing this observation, we show also evidence for an equivalent DC-field-driven structural phase transformation to a higher
symmetry phase, as observed by atom probe
tomography. Our study demonstrates the concept of nonresonant optomechanical phase control and defines novel opportunities for synthesizing hidden structural phases with unique functional properties.
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All authors Jiaojian Shi, Yijing Huang, Christian Heide, Elias Hilderbrand, Carl Friedrich Schon, Jan Kottgen, Matthias Wuttig, Burak Guzelturk, Isabel Sedwick, Yukun Li, Haowei Xu, Yuejun Shen, Pooja Donthi Reddy, Viktoryia Shautsova, Mohammad Taghinejad, Duan Luo, Mark L. Brongersma, Kunal Mukherjee, Yuki Kobayashi, Andrew F. May, Eamonn Hughes, Mariano Trigo, David A. Reis, Ju Li, Jian Zhou, Shambhu Ghimire, Aaron M. Lindenberg
Disordered Systems and Neural Networks · Cross-listed from cs.ET
Reservoir Computing with Heterogeneous Magnetic Metamaterials
R. Yagan, C. Swindells, I. T. Vidamour et al. (+5 more)
Physical reservoir computing utilizes the intrinsic nonlinear and history-dependent dynamics of physical systems to perform machine-learning tasks with minimal training overhead. Here, we introduce a nanomagnetic reservoir computer based on a heterogeneous array of interconnected
magnetic nanorings, combined with multi-channel planar
Hall effect readout. The device comprises subarrays of rings with systematically varied track widths ranging from 500 nm to 300 nm, enabling access to the heterogeneous dynamics of geometrically diverse
magnetic systems within a single reservoir. By applying time-varying input signals as modulations of a driving rotating
magnetic field, we evaluate the nanoring reservoir's performance on nonlinear signal transformation and Mackey-Glass time-series prediction tasks. We find that combining outputs from multiple width-dependent channels significantly reduces the normalized root-mean-square error compared to single-channel readout, with the optimal channel combinations depending on task requirements. These results demonstrate that
geometric heterogeneity provides an additional, experimentally accessible degree of freedom and complementary computational features. Principal component analysis further reveals that a reduced subset of correlated features captures most of the computationally relevant information while suppressing noise contributions. These results demonstrate that controlled
geometric heterogeneity enhances reservoir expressivity and suggest a route toward scalable
magnetic computing architectures in which multi-output
magnetic metamaterials serve as configurable dynamical building blocks for device networks.
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All authors R. Yagan, C. Swindells, I. T. Vidamour, G. Venkat, J. Griffiths, E. Vasilaki, M. O. A. Ellis, T. J. Hayward
Materials Science
A Dataset of Equilibrium State Configurations of Adsorption in Zeolites
Marko Petković, Rachna Ramesh, Vlado Menkovski et al. (+1 more)
Zeolites are crystalline nanoporous materials widely used in adsorption, separation, and catalytic processes. Molecular simulations are commonly used to predict adsorption properties, but most high-throughput adsorption
datasets report only ensemble-averaged quantities such as loadings or isotherms, rather than the molecular configurations from which these averages are obtained. Here, we present AdsZeo, a coordinate-resolved
dataset of
equilibrium methane adsorption configurations in aluminium-substituted, sodium-containing zeolite frameworks. The processed release contains 4,775 framework realisations derived from 191 zeolite
topologies. Each framework realisation was simulated at 13 methane pressures between 0.1 and 100 bar at 298 K using grand canonical Monte Carlo simulations, giving 62,075 production simulations in total. In addition to scalar adsorption records, the
dataset stores production-frame methane pseudo-atom coordinates, mobile Na$^+$ cation coordinates, framework atomic coordinates, per-frame loading and energy statistics, and simulation metadata in a processed DuckDB database. The release contains 12,415,000 saved production-frame records and 1,245,376,215 saved particle-coordinate records. AdsZeo provides coordinate-resolved adsorption data across variations in framework
topology, aluminium content and distribution, sodium cation arrangement, pressure, and methane loading, enabling reuse for adsorption analysis, spatial statistics, density estimation, and machine-learning models for molecular configuration generation in charged zeolite pores.
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All authors Marko Petković, Rachna Ramesh, Vlado Menkovski, Sofía Calero
Mesoscale and Nanoscale Physics
Layer-Locked Chiral Topological Superconductivity
Yijie Mo and Zhongbo Yan
We uncover a universal mechanism for realizing layer-locked topological phases. Guided by it, we investigate the realization of layer-locked
chiral topological superconductivity-the superconducting analogue of the
quantum anomalous layer
Hall effect-in a nonsymmorphic
bilayer antiferromagnetic system with s-wave pairing. We identify three distinct gate-tunable topological phases and establish a direct correspondence between the nearly quantized layer-resolved Chern numbers and the layer-locking behavior of
chiral Majorana edge states,
vortex-core Majorana zero modes, and nearly quantized thermal
Hall responses.
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Materials Science
Light-Stabilized Metastable Electronic State in NiO with Enhanced Orbital Hybridization
Thomas C. Rossi, Fabio G. Santomauro, Lars Mewes et al. (+19 more)
Light-driven control of electronic structure in correlated metal
oxides offers new opportunities for optimizing materials used in photovoltaic and photoelectrochemical technologies. We show that photoexcitation of NiO, a prototypical transparent
semiconductor and hole-transport material, across its charge-transfer gap produces a long-lived metastable state with enhanced Ni 3d-O 2p orbital hybridization. We characterize this state using Ni K-edge X-ray absorption spectroscopy, which probes how structural and electronic changes affect the unoccupied p density of states during continuous and pulsed ultraviolet excitation. Under pulsed excitation, high carrier densities of approximately 10^20 per cubic centimeter generate a state with a lifetime of approximately 600 picoseconds, in which enhanced hybridization coexists with
lattice heating. By contrast, continuous ultraviolet irradiation at much lower carrier densities of approximately 10^13 per cubic centimeter stabilizes a similar electronic state with negligible
lattice heating, demonstrating that its formation is not solely thermally driven. First-principles DFT+U+V calculations attribute the spectral changes to stronger Ni 3d-O 2p hybridization, which alters the unoccupied Ni 4p states probed by dipole-allowed K-edge transitions. We attribute this change to the dynamic screening of on-site electronic correlations following photoexcitation, which redistributes the charge density. Because orbital hybridization governs carrier transport and charge-transfer energetics, our results identify photoinduced screening as a mechanism for dynamically tuning correlated
oxides and suggest new design principles for optoelectronic materials.
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All authors Thomas C. Rossi, Fabio G. Santomauro, Lars Mewes, Janina Löffler, Dominik Kinschel, Giacomo Rossi, Mario Gutiérrez, Oliviero Cannelli, Boris V. Sorokin, Jochen Rittmann, Jakob Kel, James Budarz, Anna Wach, Adam H. Clark, Emiliano Dal Molin, Maged F. Bekheet, Albert Gili, Sebastian Praetz, Daniel Grötzsch, Delphine Cabaret, Renske M. van der Veen, Majed Chergui
Mesoscale and Nanoscale Physics
Electronic bistability, discontinuous switching and stochasticity in a two-dimensional semiconductor
S. Jana, M. Kravtsov, A. Ermakov et al. (+12 more)
Bistability - two stable electronic states under the same bias - underlies switching and
memory, but is usually absent in transistors and must be engineered through material means: doped tunnel junctions, filaments in memristors, or phase transitions. Here we demonstrate a transistor with intrinsic electronic bistability in a single chemically homogeneous
crystal. In dual-gated black phosphorus, whose band gap narrows under a perpendicular electric field due to a
giant Stark effect, the gates not only modulate carrier density but also reshape the band profile, forming interband tunnel junctions in the channel. Transport across the two-gate parameter space reveals competing conduction regimes - diffusive, two tunnelling channels and Zener breakdown - whose interplay produces negative differential conductance and transconductance, discontinuous switching, and hysteresis with the state set by gate history. Moreover, the switching remains intrinsically
stochastic, yet statistically stable within a narrow range of gate voltages, providing an electrically programmable source of randomness. Devices based on this principle should be realisable in other two-dimensional
semiconductors, opening a route to next-generation computing architectures in which nonlinearity, switching,
memory and stochasticity are integrated within a single electrostatically programmable element.
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All authors S. Jana, M. Kravtsov, A. Ermakov, X. Zhou, A. Kudriashov, L. Elesin, X. Zhou, A. L. Shilov, D. A. Svintsov, T. Taniguchi, K. Watanabe, K. S. Novoselov, A. Avsar, A. Principi, D. A. Bandurin
Mesoscale and Nanoscale Physics
Time-Reversal-Invariant Altermagnetic Acoustic Crystals
Tianzhi Xia, Han-Rong Xia, Jinglin Liu et al. (+3 more)
Altermagnets have emerged as a new class of
magnetic materials that combine
spin-split electronic bands with zero net magnetization. Extending this paradigm to classical-wave systems has, however, been fundamentally challenging because conventional realizations require broken time-reversal
symmetry (TRS). Here, we overcome this limitation by introducing two pseudospin degrees of freedom and constructing a pseudo-time-reversal operator that faithfully reproduces the action of its physical counterpart while preserving actual TRS. Building on this framework, we theoretically propose and experimentally realize the first time-reversal-invariant altermagnetic acoustic
crystal. Acoustic measurements directly reveal pseudospin-dependent band splitting–a defining hallmark of altermagnetism–under strictly TRS-preserving conditions. Moreover, the altermagnetic acoustic
crystal exhibits sublattice-pseudospin locking, enabling flexible control over acoustic pseudospin splitting and filtering. Our work establishes acoustic
crystals as a versatile platform for exploring altermagnetic physics and opens new avenues for
spin-inspired wave manipulation in nonmagnetic devices.
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All authors Tianzhi Xia, Han-Rong Xia, Jinglin Liu, Xiying Fan, Zebin Zhu, Zhen Gao
Strongly Correlated Electrons · Cross-listed from quant-ph
State preparation via measurement and feedback: pushing relations, state structures, and non-invertible symmetries
Yabo Li, Aditi Mitra and Tsung-Cheng Lu
Quantum circuits with measurements and
unitary feedback (MF) can prepare long-range entangled states in constant depth, but a systematic construction of the MF preparation
circuit for a given target state remains underexplored. We develop such a scheme for one-dimensional states, based on the notion of pushable defects: virtual-bond operators of a
matrix product state that can be pushed through the tensor at the price of a physical feedback
unitary. We show that the set of pushable defects, together with their pushing relations classifies finite-depth MF-preparable states and dictates their preparation
circuits. To each class of the target state $|A\rangle$, we associate a state $|B\rangle$ from which $|A\rangle$ can be prepared using a 1-round MF
circuit; in particular, $|A\rangle$ is preparable from a product state using a
circuit with 1 round of MF whenever $|B\rangle$ is preparable by a finite-depth local
unitary (FDLU)
circuit. For a general target state, the scheme is obtained by iterating this procedure until the associated state is FDLU-preparable. For open-boundary
matrix product states, the scheme is complete: it constructs a preparation
circuit whenever finite-depth MF preparation with left-conditioned feedback corrections is possible. Pushable defects and pushing relations thus emerge as a unifying principle for
quantum state preparation via measurements and feedback. This characterization further reveals an intrinsic connection between MF
circuits and non-invertible
symmetries: states with certain classes of pushing relations are related to a product state by Tambara-Yamagami duality operators, or by continuous cosine
symmetry operators with fusion rules $L_{\alpha} L_{\alpha'} = L_{\alpha+\alpha'} + L_{\alpha-\alpha'}$, together with their generalizations up to (not necessarily transversal) gates.
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Materials Science
Distribution of Relaxation Times analysis of evolution of Oxygen Reduction Pathways for ionic conductor infiltration on MIEC cathode
Rakhi Saha, Preethi Sudarsan, Manju Kumari et al. (+4 more)
Solid
oxide fuel
cells (SOFCs) are promising electrochemical energy conversion devices; however, the sluggish cathodic oxygen reduction reaction (ORR) remains a major limitation for intermediate-temperature operation. ORR subprocesses can be modified by infiltrating ionic Sm0.2Ce0.8O2-delta (SDC) on mixed ionic electronic SrFe0.9Ti0.1O3-delta (STF). However, the processes are indistinguishable in most cases and poorly understood using conventional equivalent
circuits. Distribution of Relaxation Times (DRT) analysis distinguishes these processes to identify the dynamics with temperature and surface reconstruction. Such analysis is being reported, revealing the connection between increase of active sites, temperature, and polarization resistance (RP). SDC infiltration preferentially accelerates oxygen surface exchange and activation processes over the relatively high frequency charge transfer process related to cathode surface at elevated temperatures for the infiltrated
cells. RP was reduced substantially with the systematic redistribution of each process to as low as 0.04 ohm.cm2 at 800 degC. This work underlines the deconvolution of the processes using DRT as a tool, and SDC infiltrated STF as a model cathode system to provide a mechanistic insight of understanding ORR kinetics and design a rationale for developing high-performance SOFC air electrodes
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All authors Rakhi Saha, Preethi Sudarsan, Manju Kumari, Hee Jung Park, Abdelkrim Mekki, Khalil Harrabi, Somaditya Sen
Strongly Correlated Electrons · Cross-listed from hep-th
Understanding Non-Split 2-Group Symmetry: (3+1)D SymTFT, Anomaly and Bordism
Zhenbang Gu, Ran Luo, Yi-Nan Wang et al. (+1 more)
We present a systematic study of finite, non-split 2-group
symmetries with a non-trivial Postnikov class, focusing on the simplest example with a $\mathbb{Z}_2$ 0-form
symmetry and a $\mathbb{Z}_2$ 1-form
symmetry, intertwined together by the non-trivial Postnikov class in $H^3(B\mathbb{Z}_2;\mathbb{Z}_2)\cong\mathbb{Z}_2$, denoted by $\mathcal{G}$. We classify the anomalies of this 2-group
symmetry for physical theories in $d$-dimensional spacetime, by computing the oriented bordism groups $\Omega_{d+1}^{\rm SO}(B\mathcal{G})$ and the
spin bordism groups $\Omega_{d+1}^{\rm Spin}(B\mathcal{G})$ for $d\leq 5$. For the case of $d=3$, we investigate the
Symmetry TFT/TO of the 2-group
symmetry $\mathcal{G}$ using the
language of fusion 2-categories, as well as (3+1)D TQFT actions, for the cases without or with the 2-group anomaly classified by $\operatorname{Hom}\left(\widetilde{\Omega}_4^{\rm SO}(B\mathcal{G}),U(1)\right) \cong H^4(B\mathcal{G};U(1))\cong\mathbb{Z}_2$. We classify the minimal topological and physical boundary conditions of the
Symmetry TFTs, and carry out the categorical Landau paradigm for such a non-split finite 2-group.
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All authors Zhenbang Gu, Ran Luo, Yi-Nan Wang, Yi Zhang
Disordered Systems and Neural Networks · Cross-listed from math.PR
Overlap distribution of the critical Sherrington-Kirkpatrick model
Hang Du and Brice Huang
We study the distribution of the two-replica overlap $R_{1,2}$ in the Ising and spherical Sherrington-Kirkpatrick models at the critical inverse temperature $\beta = 1$. Our main result shows that in both models, $R_{1,2}$ has scale $N^{-1/3}$, and the quenched distribution of $N^{1/3} R_{1,2}$ converges to an explicit random probability measure defined in terms of the reflected $\mathrm{Airy}_1$ point process. As a consequence, we characterize the limiting value of $N^{2/3} \mathbb{E} \langle R_{1,2}^2 \rangle$, answering a question of Talagrand \cite{talagrand2011mean2}. For the spherical SK model, we obtain the limit by representing the Gibbs measure as an anisotropic Gaussian on $\mathbb{R}^N$ conditioned to have norm $\sqrt{N}$, and then passing to the $\mathrm{Airy}_1$ scaling limit at the GOE spectral edge. For the Ising SK model, the proof is based on a sphere-to-cube comparison principle showing that the quenched distributions of $N^{1/3} R_{1,2}$ under the spherical and Ising Gibbs measures asymptotically coincide. This paper is a companion to \cite{du2026fluctuations}, where we introduced a related comparison principle to identify the limiting fluctuations of the SK free energy. Most of the arguments in this paper were generated using GPT-5.6 Pro, with the aim of exploring further consequences of the ideas developed in that work.
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Materials Science
Microscopic Origin of Spin Splitting in Altermagnetic CrSb Thin Films
Dai Mingyang, Song Hongquan, Kang Zhuo et al. (+2 more)
Altermagnets have recently emerged as promising materials for spintronic applications owing to their momentum-dependent
spin splitting. Among them, metallic CrSb is particularly attractive owing to its
giant spin splitting and high Néel temperature. However, the microscopic origin of the distinct
spin-splitting behaviors in bulk and thin-film CrSb remains unresolved. Here, we systematically investigate the electronic structures of CrSb slabs with different surface orientations using first-principles calculations. Although all considered slabs preserve
spin-group
symmetries compatible with altermagnetism, they exhibit markedly different electronic structures: the (2$\bar{1}\bar{1}$0) slab retains pronounced altermagnetic
spin splitting, whereas the (0001) and (10$\bar{1}$0) slabs display nearly
spin-degenerate bands. We demonstrate that dimensional reduction fundamentally changes the microscopic origin of altermagnetic
spin splitting. Unlike bulk CrSb, altermagnetic
spin splitting in thin films requires long-range inter-unit-
cell coplanar Cr–Sb hopping, while Sb–Sb hopping provides an additional contribution. The preservation or suppression of these hopping pathways explains the strong surface dependence of the
spin splitting. Our findings establish a microscopic mechanism for understanding altermagnetism in reduced dimensions and provide a general principle for engineering
spin splitting in low-dimensional altermagnetic materials.
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All authors Dai Mingyang, Song Hongquan, Kang Zhuo, Xu Yuanji, Tian Fuyang
Quantum Gases
Ground-state phase diagram and route to supersolidity in a two-component extended Bose-Hubbard model
Xuexin Qiu, Ning Bian, Yang Liu et al. (+4 more)
We investigate the ground-state phase diagram of a two-component extended Bose-Hubbard model recently realized with dipolar
excitons, using the projected entangled-pair states. For the experimentally relevant parameter regime, checkerboard, Mott-insulating, superfluid, and
vacuum phases are identified. These phases exhibit orbital-selective character, wherein the two components occupy different
quantum states, but we find no evidence for a supersolid phase. The absence of supersolidity is attributed to the strongly interaction-dominated microscopic energy scales, which severely restrict the superfluid regime. Guided by the supersolid mechanism, we further explore a nearby parameter regime with enhanced hopping of one component and identify an orbital-selective supersolid phase. Further finite bond-dimension and unit-
cell analyses establish the robustness of this phase. Our results clarify the zero-temperature phase structure of the dipolar-
exciton platform and provide a possible route toward realizing supersolidity in this setting.
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All authors Xuexin Qiu, Ning Bian, Yang Liu, Saisai He, Z. Y. Xie, Hong-Gang Luo, Jize Zhao
Soft Condensed Matter
Interface dynamics in tissue invasion
Nino Despeignes, Lila Sarfati, Marc Durand et al. (+1 more)
We rely on a hydrodynamic description of living tissues to describe the interface separating two of them with distinct constitutive properties. Using the difference in their homeostatic pressures as a control parameter, we show that the interface generates an emergent capillary surface tension that depends on the hydrodynamic scale, and that makes it very stable to large wavelengths perturbations. Using the difference of active forces the two tissues experience as a control parameter, we not only find that the front propagation mechanism shifts from the pushed wave to the Burgers wave, but we also find that the emergent surface tension is not sufficient to stabilize the interface at large enough drive and low enough viscosity.
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All authors Nino Despeignes, Lila Sarfati, Marc Durand, Frédéric van Wijland
Mesoscale and Nanoscale Physics
Interaction between Rydberg Excitons in Cuprous Oxide Revealed through Resonant Second Harmonic Generation
Andreas Farenbruch, Henje Stolz, Peter Grünwald et al. (+5 more)
We report experimental and theoretical investigations of interacting
excitons of the yellow series in cuprous
oxide (Cu$_2$O) with principal
quantum numbers up to by means of second harmonic generation (SHG). Using picosecond pulsed
laser excitation up to 10 GW/cm$^2$ peak intensity we observe a pronounced change of the spectra with increasing pump
laser intensity: an energetic shift to lower absolute energies and a spectral broadening. The absolute intensities of the spectral lines scale for low powers with the square of the pump power, but saturates at higher powers. At still higher powers the SHG intensity is actually reduced. To explain these results quantitively, we developed a semi-classical theory of resonant SHG where the process of SHG is fully coherent. The
excitons are assumed to be
bosons interacting by a distance dependent potential giving rise to both the changes in spectral line shape and the saturation by a $\it{Rydberg}$ blockade. The concomitant measurement of two-
photon absorption allows to derive quantitative values for the
exciton-
exciton interaction. While the results agree in order of magnitude with those calculated by state-of-the art atomic-like van der Waals interaction theory, the scaling with principle
quantum number is quite different. As a possible screening by an electron-hole
plasma created by three-
photon absorption into blue and violet band states could be ruled out, our results point toward fundamental differences between
excitons and atoms.
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All authors Andreas Farenbruch, Henje Stolz, Peter Grünwald, Dirk Semkat, Nikita Siverin, Dmitri R. Yakovlev, Dietmar Fröhlich, Manfred Bayer