Mesoscale and Nanoscale Physics
Kinetic coefficients of two-dimensional electrons with strong Zeeman splitting
Yu. O. Alekseev, P. S. Alekseev and A. P. Dmitriev
In modern nanostructures with very low defect densities, has recently been realized a hydrodynamic regime of electric transport, in which two-dimensional (2D) electrons form a viscous fluid due to frequent electron-electron collisions. Many bright transport phenomena have been observed in these systems. Of particular interest are two-component hydrodynamic electron systems, where a richer variety of phenomena becomes possible, than in one-component systems. A simplest way to implement and control a two-component 2D electron system is to place a structure with 2D electrons in a
magnetic field with a large component in the 2D plane, that leads to a Zeeman splitting of the electron energy spectrum into two subbands. Here we develop a microscopic model of hydrodynamic transport in such system. By solving the kinetic equation, we calculate the electron-electron relaxation rates of the first and second angular harmonics of the two-component distribution function. Then we derive the hydrodynamic balance equations with the kinetic coefficient containing these rates. Namely, are taken into account the shear viscosity in each fluid component and the effect of the friction between the two components. The last leads to equalization of the hydrodynamic velocities in the two subbands. The obtained equations can be used to explain the results of puzzling magnetotransport experiments in ultra-pure nanostructures in a strong oblique
magnetic field.
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Statistical Mechanics
Tripartite information of free fermions: a universal entanglement coefficient from the sine kernel
Aleksandrs Sokolovs
We study the tripartite information I_3 of free
fermions on two-dimensional
lattices partitioned into three adjacent strips of width w. Translation invariance yields the exact decomposition I_3 = \sum_{k_y} g(k_F(k_y) w), where g(z) is a universal function of the scaling variable z = k_F w, determined by the spectrum of the sine-kernel (Slepian) integral operator. We find that g(z) has a unique zero at z* = 1.329 +/- 0.001: modes with k_F w < z* violate monogamy of mutual information (g > 0), while modes with k_F w > z* satisfy it (g < 0). The central analytical result is g(z) = cz + O(z^3 ln z) with c = 3 ln(4/3)/pi ~ 0.2747, derived from the rank-1 limit of the sine kernel. Two exact cancellations – of the z ln z area-law terms and of the z^2 terms – are intrinsic to the I_3 combination. The coefficient c generalizes to n-partite information: c_n = (n/pi) ln R_n with R_n a rational number from binomial combinatorics. For Renyi
entropy of index alpha, we show that g_alpha(z) ~ z^alpha for alpha < 2 and g_2(z) = -(8/pi^3)z^3: von Neumann
entropy (alpha = 1) uniquely gives linear sensitivity to Lifshitz transitions, while Renyi-2 gives only cubic sensitivity. We verify all predictions on square, triangular, and cubic
lattices. DMRG calculations on the interacting t-V model provide evidence that the linear coefficient is independent of the Luttinger parameter K.
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Superconductivity
Suppression of Spectral Gap and Flat Bands on a Cuprate Superconductor Side-Surface
Gabriele Domaine, Mihir Date, Sydney K. Y. Dufresne et al. (+27 more)
Side surfaces of cuprate
superconductors are expected to display a suppressed $d$-wave order parameter and zero-energy topological flat bands with a large density of states, making them susceptible to
symmetry broken orders. Yet such surfaces have never been investigated with momentum-resolved, surface-sensitive probes, because high-temperature
superconductors rarely cleave along them. Using focused-ion-beam milling to define a controlled breaking point, we expose pristine (110) side surfaces of overdoped La$_{2-x}$Sr$_x$CuO$_4$ ($x=0.22$) suitable for angle-resolved photoemission. We observe the suppression of the superconducting spectral gap within our energy resolution ($\sim 4~\mathrm{meV}$), and surprisingly, the expected zero-energy flat band peak is also suppressed, despite the high topographic quality of the surface. Self-consistent Bogoliubov–de~Gennes calculations show that the measured
geometric roughness of the cleaved surface is too weak to eliminate these modes. The calculations further demonstrate that bulk inhomogeneities characteristic of high-temperature
superconductors, modelled as moderate Anderson-type disorder, can broaden the flat-band states beyond detectability. Our results provide the first momentum-resolved view of the electronic structure on a cuprate side surface and reveal disorder as the key factor currently preventing appearance of flat bands and their associated correlated orders.
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All authors Gabriele Domaine, Mihir Date, Sydney K. Y. Dufresne, Natalie Lehmann, Daiyu Geng, Tohru Kurosawa, Amit Kumar, Jiaju Wang, Tianlun Yu, Chien-Ching Chang, Swosti P. Sarangi, Ding Pei, Yiran Liu, Julia Küspert, Shigemi Terakawa, Markel Pardo Almanza, Jiabao Yang, Izabela Biało, Matthew D. Watson, Timur K. Kim, Stephen M. Hayden, Kritika Singh, Banabir Pal, Matteo Minola, Johan Chang, Naoki Momono, Migaku Oda, Stuart S. P. Parkin, Andreas P. Schnyder, Niels B. M. Schröter
Strongly Correlated Electrons
A composite electron-lattice order: electronic nematicity of 2DEG and polarization density waves at a near-ferroelectric interface
Fei Yang, Zhi-Yang Wang and Long-Qing Chen
We consider a two-dimensional electron gas (2DEG) formed at a near-ferroelectric interface and strongly coupled to polar
phonons. Through a self-consistent microscopic many-body calculation, we show that the coupled system stabilizes a composite electron-
lattice ordered state in which the
lattice polarization spontaneously forms a polarization density wave (PDW), accompanied by an electronic stripe order in the 2DEG. This intertwined order partially reconstructs the electronic spectrum and generates a twofold quasiparticle anisotropy, giving rise to electronic nematicity at the single-particle level. However, under strong external electric fields, the nematic response becomes dominated by the collective sliding dynamics of the composite order: the sliding motion overwhelms the quasiparticle anisotropy and produces a strongly enhanced nematic signal with higher-order angular harmonics. The theory offers a natural explanation for several anomalous transport and anisotropic responses recently observed at the KTaO$_3$ (111) interface. We also estimate the mean-field transition temperature of this emergent ordered state, obtaining good agreement with experiments, and analyze its
evolution with several tuning parameters. The proposed composite order, along with the field-induced crossover from quasiparticle-driven to sliding-dominated nematicity, provides a distinct mechanism of nematicity arising from many-body effects and collective dynamics in critical electron-
boson systems, with applicability beyond ferroelectric platforms.
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Mesoscale and Nanoscale Physics
Scaling of silicon spin qubits under correlated noise
Juan S. Rojas-Arias, Leon C. Camenzind, Yi-Hsien Wu et al. (+8 more)
The path to fault-tolerant
quantum computing hinges on hardware that scales while remaining compatible with
quantum error correction (QEC). Silicon
spin qubits are a leading hardware candidate because they combine industrial fabrication compatibility with a nanoscale footprint that could accommodate millions of
qubits on a chip. However, their suitability for QEC remains uncertain since spatially correlated noise naturally emerges from the resulting close proximity of
qubits. These correlations increase the likelihood of simultaneous errors and erode the redundancy that QEC depends on. Here we quantify the spatial extent of noise correlations in a five-
qubit silicon array and assess their impact on QEC. We identify two distinct sources of correlated noise: global
magnetic field drifts that generate perfectly correlated fluctuations, and charge noise from two-level fluctuators that produces short-range correlations decaying within neighboring
qubits. While
magnetic drifts represent a critical correlated noise source that can compromise QEC, they can be mitigated. In contrast, the measured charge noise correlations are moderate, electrically tunable, and compatible with fault-tolerant operation with minimal
qubit overhead. Our results establish quantitative
benchmarks for correlated noise and clarify how such correlations impact the viability of
quantum error correction in scalable
qubit arrays.
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All authors Juan S. Rojas-Arias, Leon C. Camenzind, Yi-Hsien Wu, Peter Stano, Akito Noiri, Kenta Takeda, Takashi Nakajima, Takashi Kobayashi, Giordano Scappucci, Daniel Loss, Seigo Tarucha
Mesoscale and Nanoscale Physics
Current-control of chaos and effects of thermal fluctuations in magnetic tunnel junctions
Ryo Tatsumi, Shinji Miwa, Hiroaki Matsueda et al. (+1 more)
We theoretically investigate the chaotic behavior of
spin-torque
ferromagnetic resonance in
magnetic tunnel junctions (MTJs) with perpendicular
magnetic anisotropy under thermal fluctuations. By calculating the Lyapunov exponent based on the Landau-Lifshitz-Gilbert equation, we demonstrate that an MTJ characterized by a double-well potential, composed of uniaxial
magnetic anisotropy and an external
magnetic field, exhibits chaotic magnetization dynamics that can be controlled by means of the DC current bias. Furthermore, we find that thermal fluctuations help to induce these chaotic magnetization dynamics, which can be regarded as noise-induced chaos. This research provides a basis for
brain-inspired computing using spintronic devices and advances the understanding of the interplay between thermal fluctuations and chaos in magnetization dynamics.
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All authors Ryo Tatsumi, Shinji Miwa, Hiroaki Matsueda, Takahiro Chiba
Mesoscale and Nanoscale Physics
Millisecond-long electron spin lifetime in CsPbI$_3$ perovskite nanocrystals revealed by optically detected magnetic resonance
Vasilii V. Belykh, Mikhail M. Glazov, Sergey R. Meliakov et al. (+7 more)
Perovskite nanocrystals are a convenient model system for optical
spin orientation and manipulation. However, its real potential might be underestimated due to the incomplete knowledge on
spin relaxation times, which are obscured by the limited sensitivity of measurement techniques as well as by the insufficient understanding of the
spin relaxation mechanisms in perovskites. In this work, we study the
spin relaxation of charge carriers in perovskite nanocrystals both experimentally and theoretically. We address the electron and hole
spins in CsPbI$_3$ nanocrystals embedded in a glass
matrix by the resonant
spin inertia technique based on optically detected
magnetic resonance. It allows us to determine the longitudinal
spin relaxation time $T_1$ separately for electrons and holes, the $g$ factors, and the effective Overhauser field of the
nuclear spin bath. At a temperature of 1.6 K, the $T_1$ time for electrons can be as long as 0.9 ms. We reveal the effect of the time-varying
nuclear field fluctuations, which enhances the electron
spin relaxation at low
magnetic fields, and measure a rather long
nuclear spin correlation time of about 60 $\mu$s. We develop a model of the
spin relaxation in nanocrystals based on a two-LO-
phonon Raman process, which explains the observed temperature dependence of the time $T_1$.
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All authors Vasilii V. Belykh, Mikhail M. Glazov, Sergey R. Meliakov, Dmitri R. Yakovlev, Evgeniya V. Kulebyakina, Mikhail L. Skorikov, Mikhail V. Kochiev, Maria S. Kuznetsova, Elena V. Kolobkova, Manfred Bayer
Quantum Gases
First-order transition into a topological superfluid state in an atom-cavity system
Hannah Kleine-Pollmann and Ludwig Mathey
We propose to combine Bose-Einstein condensation in higher Bloch bands and a driven-dissipative cavity-BEC system into a hybrid light-matter platform. Specifically, the condensate is trapped in a bipartite $s$-$p_x$-$p_y$-
lattice, with a tunable energy offset. This enables a controlled population transfer from the $s$-orbital to the nearly degenerate $p_x$ and $p_y$ orbitals. The system forms a
chiral ground state with $p_x \pm i p_y$
symmetry, with staggered orbital currents. By increasing the transverse pump strength, we drive the system into the superradiant phase, resulting in a self-organized, density checkerboard, which rectifies the staggered
chiral order into a topological superfluid state. Using truncated Wigner simulations and complementary mean-field analysis, we determine the phase transition into this state as first order. Our results show that higher-band condensates coupled to a cavity provide a promising platform for engineering non-trivial orbital order and topological superfluid phases in
quantum optical many-body systems.
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Soft Condensed Matter
Nature of granular drag in microgravity
Tivadar Pongo, Tianhui Liao, Jinchen Zhao et al. (+4 more)
The influence of
gravity on the drag force acting on a projectile impacting granular media is investigated experimentally via embedded inertial measurement unit (IMU) sensor and numerically through discrete element method (DEM) simulations. As
gravity approaches zero, inertial drag dominates, yielding qualitatively different scaling laws and cavity dynamics. Analogous to fluid dynamics, we define a dimensionless granular drag coefficient $C_{\rm gd}$, which is found to stay largely at a constant $\sim 1.2$ in microgravity while an additional term inversely proportional to impact velocity arises in the presence of
gravity. The constant term can be understood from momentum transfer along the penetration direction while the additional term suggests the influence of internal stress built-up due to
gravity. Similar discrepancy is also found for the initial peak of the drag force. This analogy provides novel insights into the nature of granular drag in microgravity and sheds light on future space missions.
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All authors Tivadar Pongo, Tianhui Liao, Jinchen Zhao, Valentin Dichtl, Simeon Voelkel, Raul Cruz Hidalgo, Kai Huang
Other Condensed Matter
Anisotropic skyrmion liquid phase
Daniel Schick, Tim Matthies, Thomas Mutschler et al. (+2 more)
The nature of the melting transition in two-dimensional systems of particles has attracted considerable research
attention since the development of Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory. The hexatic phase proposed by this theory has been recently identified experimentally in ensembles of
magnetic skyrmions, quasiparticles formed in a magnetically ordered
crystal. Here, we use quasiparticle dynamical simulations to study how the anisotropy of the skyrmion-skyrmion interactions induced by the atomic
lattice influences the melting transition. For isotropic interactions, we find a transition from a solid phase through a hexatic phase stable in a narrow temperature range to an isotropic
liquid phase. However, if the interactions between skyrmions are forced to be anisotropic by the atomic
lattice, then a direct solid-
liquid transition can be observed with orientational order persisting up to temperatures of 30 K in the
liquid phase.
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All authors Daniel Schick, Tim Matthies, Thomas Mutschler, Levente Rózsa, Ulrich Nowak
Strongly Correlated Electrons
Kitaev model in a magnetic field: stable emergent structure, degenerate classical ground states, and reentrant topology
Sheikh Moonsun Pervez
We have studied the anti-
ferromagnetic Kitaev model on a honeycomb
lattice under the Zeeman field, using an extensive Majorana mean-field analysis. When the
magnetic field is along a specific Cartesian axis, we find that the emergent fields exhibit direction-dependent stabilization up to a certain critical strength of the external field. For a conical
magnetic field, the characteristics of the emergent intermediate state are elusive. Our mean-field analysis reveals the existence of two distinct phases in the intermediate region. First, the system enters a disordered phase, where emergent-field densities converge to random values, and the Chern number is ill-defined. The magnitude of magnetization also fluctuates and remains less than unity, indicating a strong
quantum effect. In the second phase, emergent-field densities attain vanishingly small values. In this phase, the magnetization components fluctuate heavily, but the magnitude of the magnetization vectors becomes unity, indicating highly degenerate classical ground states. We perform exact diagonalization calculations that qualitatively support some of the mean-field results. We extend our study to the anisotropic limit of the Kitaev coupling parameters. When the couplings are beyond the triangular inequality, the pure Kitaev model is known to host a topologically trivial gapped
quantum spin liquid. We find that, for intermediate strengths of a conical
magnetic field,
topology shows a reentrant behavior.
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Materials Science · Cross-listed from physics.flu-dyn
Phase-field investigation of non-isothermal solidification coupled with melt flow dynamics
Timileyin David Oyedeji, Aaron Brunk, Yangyiwei Yang et al. (+3 more)
Solidification, coupled with melt flow, plays a critical role in determining the microstructure and properties of materials in several manufacturing processes. Phase-field models coupled with the Navier-Stokes equations are widely used to model and simulate these dynamics. However, most existing models neglect essential thermodynamic couplings, particularly the capillary (Korteweg) stress in the momentum equation. This stress, which arises from the coupling between the phase field and the melt flow, accounts for thermal capillary effects during non-isothermal solidification. Neglecting it leads to models inconsistent with non-
equilibrium thermodynamics and incapable of capturing capillarity-driven melt flow. In this work, we present a thermodynamically consistent, non-isothermal phase-field model for solidification coupled with melt flow, incorporating cross-coupling terms and explicitly including the Korteweg stress in the momentum equation. Model validation is performed for solidification-only cases, followed by simulations of dendritic growth under melt flow. The results show that thermal capillary effects induce flow near the interface, influencing dendrite tip velocity and morphology. Simulations under forced convection further demonstrate asymmetric dendrite growth due to the imposed flow field. Additionally, we numerically demonstrate the influence of viscosity interpolation schemes on enforcing the no-slip boundary condition in phase-field models with melt flow.
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All authors Timileyin David Oyedeji, Aaron Brunk, Yangyiwei Yang, Herbert Egger, Holger Marschall, Bai-Xiang Xu
Materials Science
Intrinsic Electric Field Driven High Sensitive Photodetection in Alloy TMDC MoSSe
Chumki Nayak, Suvadip Masanta, Shubhadip Moulick et al. (+7 more)
Alloying offers an effective way to improve the functionality of transition metal dichalcogenides (TMDCs) in both fundamental research and optoelectronic applications, as it allows for engineering their electronic and optical properties. This study investigates the optoelectronic properties of CVD-synthesized
alloy MoSSe, which exhibits an inherent out-of-plane dipole moment, arising from asymmetry in S and Se atoms on either side of the Mo layer, as confirmed by piezoelectric force microscopy, polarization-resolved second harmonic generation studies and theoretical first-principles calculations. Time-resolved photoluminescence measurements reveal an extended
exciton radiative recombination lifetime in MoSSe, attributed to electron-hole wavefunction separation by the dipole moment, which improves photodetection by facilitating enhanced electron-hole separation before recombination. The device demonstrates significant responsivity over broad spectral range. By employing the photogating effect, the device response can be switched from slow to fast modes. These findings are further supported by illumination intensity-dependent photoluminescence and Raman measurements, underscoring the potential of polar TMDCs in future optoelectronic devices.
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All authors Chumki Nayak, Suvadip Masanta, Shubhadip Moulick, Manotosh Pramanik, Atanu Kabiraj, Satchidananda Rath, Sukanya Ghosh, Atindra Nath Pal, Bipul Pal, Achintya Singha
Statistical Mechanics
Ising models on the hydrogen peroxide and other lattices
Xiaofeng Qian, Youjin Deng, Lev N. Shchur et al. (+1 more)
We perform a Monte Carlo analysis of the Ising model on many three-dimensional
lattices. By means of finite-size scaling we obtain the critical points and determine the scaling dimensions. As expected, the critical exponents agree with the three-dimensional Ising universality class for all models. The irrelevant field, as revealed by the correction-to-scaling amplitudes, appears to be relatively large. Combining the Monte Carlo results for the hydrogen peroxide
lattice with those for five other three-dimensional
lattices, we obtain a set of data covering a wide range of the irrelevant temperature field. This is helpful in the determination of the parameters describing the corrections to scaling. As a consequence, new results are obtained for the universal parameters describing Ising criticality in three dimensions, with reduced error margins in comparison with earlier Monte Carlo analyses. The critical exponents describing the thermodynamic singularities are determined by the temperature renormalization exponent $y_t = 1.58693 (9)$ and the
magnetic renormalization exponent $y_h = 2.48178 (5)$. The corrections to scaling are governed by the irrelevant exponent $y_1 = -0.821 (5)$.
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All authors Xiaofeng Qian, Youjin Deng, Lev N. Shchur, Henk W.J. Blöte
Mesoscale and Nanoscale Physics
A simple scheme to realize the Rice-Mele model in acoustic system
Tianzhi Xia, Xiying Fan, Qi Chen et al. (+2 more)
The Rice-Mele (RM) model, as a paradigmatic extension of the Su-Schrieffer-Heeger (SSH) chain, plays a pivotal role in understanding topological phases and quantized adiabatic transport in one-dimensional systems. Its realization in acoustic systems, however, has been hindered by the need for simultaneous precise modulation of on-site potentials and couplings. In this work, we demonstrate a method to linearly tune on-site potentials and couplings, thus realizing an acoustic Rice-Mele model. During parameter
evolution, the system exhibits a Thouless pump, with the acoustic field distribution adiabatically shifting from the left edge through the bulk to the right edge, fully consistent with tight-binding model predictions. Moreover, the strategy of leveraging
geometric parameters to linearly and precisely control on-site potentials and couplings is highly effective and universal for designing acoustic metamaterials, and it can be extended to other classical wave systems.
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All authors Tianzhi Xia, Xiying Fan, Qi Chen, Yuanlei Zhang, Zhe Li
Mesoscale and Nanoscale Physics
Sichun Zhao, Junlin Xiong, Ji Zhou et al. (+3 more)
Two-dimensional (2D)
superconductors provide a powerful building block for engineering emergent
quantum states shaped by reduced dimensionality, enhanced
quantum fluctuations, and interfacial
symmetry breaking. In van der Waals
heterostructures, atomically sharp and
lattice-mismatch-free interfaces enable superconductivity to be deliberately coupled with magnetism,
spin orbit interaction, and band
topology, allowing collective electronic orders to be combined and reconfigured in ways unattainable in bulk materials. This Review summarizes recent advances in vdW
heterostructures of 2D
superconductors, focusing on
superconductor/magnet,
superconductor/topological material, and
superconductor/
superconductor junctions. We discuss the microscopic mechanisms underlying proximity effects and highlight how interfacial exchange fields,
spin orbit coupling, and twist-controlled tunneling give rise to unconventional pairing, long-range
spin-triplet supercurrents, nonreciprocal Josephson transport, and topological superconductivity potentially hosting Majorana bound states. Beyond their fundamental significance, the ability to controllably generate topological and nonreciprocal superconducting states positions 2D
superconductor heterostructures as promising building blocks for emerging
quantum technologies, including ultra-sensitive
quantum sensing, programmable superconducting logic, and energy-efficient
quantum and neuromorphic computing architectures. Looking forward, advances in materials synthesis, interface engineering, and device integration are expected to further expand the scope and functionality of 2D
superconductor heterostructures, reinforcing their role as a central platform for exploring and controlling emergent
quantum phases.
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All authors Sichun Zhao, Junlin Xiong, Ji Zhou, Shi-Jun Liang, Bin Cheng, Feng Miao
Materials Science
Dual-wavelength control of charge accumulation in rubrene microcrystals with anisotropic conductivity
Moha Naeimi, Ingo Barke and Sylvia Speller
Previously, a novel type of rubrene microcrystals was reported, forming two distinct sectors – diamond- and triangular-shaped – that exhibit pronounced contrasts in photoluminescence (PL) spectra and
exciton dynamics. In the present work, their internal electronic structure is investigated using time-of-flight photoemission electron spectroscopy (TOF-PES), revealing that the two sector's different charging characteristics arising from anisotropic conductivities. Upon photoemission via a one-
photon photoemission (1PPE) process excited by 6.2 eV (200 nm)
photons, the diamond-shaped sectors accumulate significant charge, whereas the triangular sectors remain essentially uncharged. The charge accumulation in the diamond sectors can be neutralized by additional sub-threshold illumination, which generates charge carriers through internal photoeffect. The dynamics and energetics of the observed band shifting is described quantitatively by a model combining surface capacitance and drift-
diffusion. These crystalline systems enable the creation of built-in charge landscapes that can be manipulated both spatially and temporally.
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Mesoscale and Nanoscale Physics
Jarosław Pawłowski and Mateusz Krawczyk
We introduce a generalizable framework for identifying effective
Hamiltonians directly from experimental data in solid-state
quantum systems. Our unsupervised autoencoder-based approach incorporates the governing physics (here, the S-
matrix formalism) directly into the decoder, enabling physically meaningful
Hamiltonian inference without labeled
Hamiltonian parameters. Through numerical experiments on a triple
quantum dot chain, we demonstrate automated characterization of programmable solid-state simulators from transport measurements. The model accurately infers
Hamiltonian parameters and generalizes beyond the training domain, while exhibiting finite capacity as the parameter space becomes increasingly broad or diverse. We further demonstrate robustness to noisy measurements and show that the model can be trained on transport data generated outside the
Hamiltonian family assumed by the physics decoder, while still identifying meaningful effective parameters.
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Materials Science
Thermodynamic and transport properties of high-quality single crystals of the altermagnet CrSb
Shubhankar Paul, Atsutoshi Ikeda, Giordano Mattoni et al. (+2 more)
Altermagnetism (AM) is an emerging
magnetic order unifying essential characteristics of
ferromagnetic and
antiferromagnetic states. The CrSb has attracted significant interest owing to its large altermagnetic
spin-splitting energy. In this paper, we present the growth details of high-quality single
crystals of CrSb using the self-flux method and investigate their physical properties. We obtained large (001) oriented hexagonal
crystals, up to 2~$\times$~2.5~$\times$~1~mm$^3$ in size with residual resistivity ratio $\sim$ 11. A pronounced positive magnetoresistance of up to 80% is observed at 3.5 K. Most strikingly, the room temperature specific heat value exceeds the Dulong-Petit limit, being attributed to a broad
magnon contribution from the altermagnetic order of CrSb. The specific heat fit reveals a
magnon energy gap $\sim$ 16 $\pm$ 1 meV. Further, ac susceptibility measurements demonstrate the absence of superconductivity down to 0.1 K. These findings underscore CrSb as a viable altermagnet for room temperature magnonic and spintronic applications.
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All authors Shubhankar Paul, Atsutoshi Ikeda, Giordano Mattoni, Shingo Yonezawa, Chanchal Sow
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Charging power enhancement at the phase transition of a non-integrable quantum battery
D. Farina, M. Sassetti, V. Cataudella et al. (+2 more)
Exploiting many-body interaction and critical phenomena to improve the performance of
quantum batteries is an emerging and promising line of research. A central question in this direction is whether
quantum phase transitions can enhance the charging energy or the power. While preliminary works have addressed this problem in fine-tuned integrable models, its characterization in non-integrable systems remains limited due to the demanding numerical requirements. Here, we investigate a one-dimensional Axial Next-Nearest-Neighbor Ising model as an example of non-integrable
quantum battery charged via a
quantum-quench protocol. In contrast to integrable cases, we find that criticality in this setting can lead to a pronounced enhancement of the charging power. Our findings inform
quantum-battery design of many-
qubit systems and are amenable to experimental verification on current
quantum-simulation platforms, including neutral-atom arrays.
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All authors D. Farina, M. Sassetti, V. Cataudella, D. Ferraro, N. Traverso Ziani
Strongly Correlated Electrons
Emergent quantum phenomena in two-dimensional 1T-TaS2
Haiyang Chen, Zhiqiang Sun and Peng Chen
Strong electron correlation drives 1T-TaS2 from a half-filled metallic state into a Mott insulating phase, coexisting with a charge density wave at low temperatures. Under external stimuli such as pressure or ionic gating, superconductivity emerges in 1T-TaS2, exhibiting an intricate relationship of competition and coexistence with the charge density wave order. In the two-dimensional (2D) limit, enhanced
quantum fluctuations can stabilize a
quantum spin liquid (QSL) state in the Mott
insulator. This review summarizes recent advances in understanding these
quantum states in 2D 1T-TaS2 from the perspective of angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), with a focus on the dimensionality effect on its electronic structure. We outline the signatures of QSL state in electronic spectra and discuss how this state can be revealed in the family of this material through experimental approaches beyond conventional probes such as
neutron scattering. The role of Kondo effect in detecting spinon excitations is further discussed. Finally, we suggest future experimental directions and highlight how external perturbations such as gating and light excitation offer versatile pathways to control and exploit these intertwined
quantum states.
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Mesoscale and Nanoscale Physics
Gate Stack Engineering for High-Mobility and Low-Noise SiMOS Quantum Devices
Md. Mamunur Rahman, Ensar Vahapoglu, Kok Wai Chan et al. (+16 more)
We systematically investigate the interplay between materials engineering,
quantum transport, and low-frequency charge noise in silicon metal–
oxide–
semiconductor (SiMOS)
quantum devices. By combining
Hall-bar transport measurements with charge-noise spectroscopy of gate-defined
quantum dots, we identify correlations between gate-stack design, carrier mobility, and electrostatic noise, providing an experimental case study of material and process dependencies relevant to low-noise, high-mobility operation.
Hall-bar studies reveal that increasing the atomic-layer-deposition temperature of Al$_2$O$_3$ markedly enhances mobility, whereas the choice of oxidant has little impact. Devices incorporating HfO$_2$ exhibit improved carrier mobility, an interesting observation that can plausibly be attributed to defect passivation associated with aluminum
diffusion from the gate metal into the HfO$_2$ layer. Charge-noise measurements show a strong correlation between higher mobility and reduced noise, with TiPd-gated devices displaying both degraded transport and elevated charge noise. In contrast, the poly-Si-gated CMOS-foundry device achieves the lowest noise levels. Finally, dual-feedback dot–sensor stability mapping demonstrates enhanced charge stability in devices with the gate stacks studied here, underscoring their promise for scalable, high-fidelity silicon
spin-
qubit platforms.
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All authors Md. Mamunur Rahman, Ensar Vahapoglu, Kok Wai Chan, Tuomo Tanttu, Ajit Dash, Jonathan Yue Huang, Steve Yianni, Venkatesh Chenniappan, Jesús D. Cifuentes, Fay Hudson, Christopher C. Escott, Yik Kheng Lee, Nard Dumoulin Stuyck, Arne Laucht, Andrea Morello, Andre Saraiva, Jared H. Cole, Andrew S. Dzurak, Wee Han Lim
Materials Science
HERB: a unified framework for the evaluation of Hydrogen Embrittlement mechanisms driven by the Rice-Beltz concept
Kai Zhao
The multiscale picture of hydrogen embrittlement (HE) mechanisms has been under controversy for a long time. Here I report a thermomechanically-consistent HERB framework driven by the Rice-Beltz concept meanwhile incorporating the hydrogen transport near the crack-tip and void growth within the plastic zone. Triggered solely by dislocation emission from the crack tip, the HERB theory unifies multiple HE mechanisms, such as HEDE, HELP, NVC and HESIV within a single framework. Specifically, a generalized model for predicting the hydrogen-informed dislocation emission is established by incorporating the Rice-Beltz model with the transition state theory. Accounting for the dynamic variation of the trapping energy of spherical inclusions, hydrogen transport is modeled in the dislocation free zone in front of the crack tip. Semi-analytical expressions of the density of geometrically necessary dislocations are obtained by incorporating the Hutchinson-Rice-Rosengren solution with the conventional theory of mechanism-based strain gradient plasticity model. By exploring the feasibility of
stochastic analysis, the present theory demonstrates that the hydrogen-informed void dynamics is dominated by the dislocation density between the limits of Lifshitz-Allen-Cahn and Lifshitz-Slyozov-Wagner laws, even though individual events remain unpredictable. These insights fundamentally reshape hydrogen/dislocation interactions across multiple scales, including the core width, short-range and long-range levels.
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Materials Science
Unlocking the Potential of Ni2+ and Ni2+-Cr3+ Synergy for Bifunctional Pressure and Temperature Optical Sensing
M. Szymczak and L. Marciniak
Reliable simultaneous optical sensing of pressure and temperature under extreme and dynamically fluctuating conditions remains a major challenge due to intrinsic cross-sensitivity between these two thermodynamic parameters.
Multimodal systems enabling simultaneous yet fully decoupled monitoring of both parameters are therefore highly sought after. Here, we demonstrate that the synergistic interplay between Cr3+ and Ni2+ luminescence provides a platform for bifunctional temperature-pressure sensing with independent readout channels. Two complementary detection strategies were systematically investigated: ratiometric approach based on luminescence intensity ratio and kinetic approaches exploiting emission decay dynamics. Among the kinetic strategies, a time-gated dual-ion lifetime concept - introduced here for the first time for luminescence manometry - enables pressure readout with record-high relative sensitivity reaching 148.33% GPa-1 while exhibiting complete immunity to temperature fluctuations. Conversely, temperature sensing is achieved via time-gated single-ion Ni2+ luminescence, ensuring high thermometric performance with negligible pressure-induced interference. Importantly, this work study, for the first time, the potential of Ni2+ ions for application in near-infrared luminescence manometry. The unique combination of ultrahigh sensitivity,
multimodal readout capability, and possibility of near-infrared operation positions the Ni2+-Cr3+ luminescence synergy as a
benchmark platform for next-generation bifunctional optical sensors, enabling reliable operation in complex, dynamically evolving, and optically demanding environments.
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Soft Condensed Matter
Riding the Wave: Polymers in Time-dependent Nonequilibrium Baths
Bhavesh Valecha, Jens-Uwe Sommer and Abhinav Sharma
Directed transport is a characteristic feature of numerous biological systems in response to signals such as nutrient and chemical gradients. These signals often depend on time owing to the high complexity of interactions in these systems. In this study, we focus on the steady-state behavior of polymeric systems responding to such time-dependent signals. We model them as ideal Rouse
polymers submerged in a nonequilibrium bath, which is described by a spatially and temporally varying self-propulsion wave field. Through a coarse-graining analysis, we show that these
polymers display rich emergent response to the temporal stimuli as a function of their length and
topology. In particular, long
polymers and structures with ring and
star topologies ride the wave, displaying a positive drift in the direction of the wave. Whereas, shorter
polymers and fully connected structures drift against the wave signal. We confirm these analytical predictions with robust numerical simulations, showing that the response of polymeric systems to temporal stimuli can be controlled by the
topology or the length of the
polymer.
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Materials Science · Cross-listed from physics.ins-det
Capacitively Coupled GaAs p-i-n/Substrate Photodetector with Ohmic Contacts on Lightly Doped n-GaAs for Hard X-Ray Imaging
V.G. Harutyunyan, S.D. Zilio, M. Colja et al. (+5 more)
In this work, we present a capacitively coupled GaAs p +-i-n/substrate photodetector (CC-GaAs PIN/S PD), which also represents a preliminary step toward 3D detection (x, y, time) of high-energy X-ray pulses. Although the final 3D detector will be based on a separate absorption and multiplication avalanche photodiode (SAM APD) design, the present device exhibits characteristics that offer valuable insights into the performance expected once a multiplication layer is incorporated into the final device. In particular, we present a fabrication strategy that employs multi-step annealing in the low-temperature range of 280 330C to achieve Cr/Au ohmic contacts on lightly doped n-GaAs, which is also required for the photodetector architecture. Simultaneously, the same contact preparation process was applied to p + GaAs. Furthermore, the fabricated CC-GaAs PIN/S PD includes an additional contact designed to reduce leakage current by applying the same bias as that of the anode. Measurements performed using an 80 MHz
laser demonstrated the photodetector's ability to detect pulses corresponding to 10^6 electrons per pulse.
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All authors V.G. Harutyunyan, S.D. Zilio, M. Colja, M. Cautero, G. Cautero, L. Sbuelz, D. Curcio, G. Biasiol
Materials Science
Nanocrystalline structure and strain in magnesium under extreme dynamic compression
Daria A. Komkova, Alexey Yu. Volkov and Evgeny F. Talantsev
The study of materials behavior under extreme conditions is fundamental to science and modern technology. Fast ramp compression is a unique method for exploring materials behavior and phase transformations under extreme conditions. One unexplored feature of this method is the nanoscale structure of the material under dynamic compression. This leaves a gap in understanding the details of phase transformations under fast ramp compression. Here, we made a first step in the exploration by applying the Williamson-
Hall (WH) analysis to X-ray diffraction data (XRD) measured in magnesium subjected to fast ramp compression at four pressures. We found that at $P = 309 GPa$ magnesium in bcc-like phase has an average crystalline size $D = (2.2 \pm 0.7) nm$ and microstrain $\varepsilon = (-0.011 \pm 0.007)$. At $P = 409 GPa$, magnesium demonstrates $D = (4.5 \pm 3) nm$ with $\varepsilon = (-0.003 \pm 0.007)$. At $P = 563 GPa$, Fmmm magnesium has crystalline size $D = (2.6 \pm 0.5) nm$ with microstrain $\varepsilon = (-0.004 \pm 0.004)$. At $P = 959 GPa$, we revealed that sh-magnesium exhibits average size of $D > 12 nm$ and relatively high value of microstrain $\varepsilon = (0.011 \pm 0.002)$. In the result, we report the first microstructural
evolution insights of magnesium under fast ramp compression.
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Strongly Correlated Electrons
Coherent magnetic excitations in a topological Kondo semimetal
Xiaoying Zheng, Devashibhai T. Adroja, Hiroaki Kadowaki et al. (+9 more)
In Kondo
insulators the many-body Kondo
lattice effect drives the formation of bands containing heavy charge carriers with a hybridization gap, leading to insulating properties. These renormalized bands can host non-trivial
topologies driven by strong electron-electron interactions, but probing narrow heavy bands at low temperatures is challenging. We use inelastic
neutron scattering (INS) to probe the Kondo
lattice CeNiSn, which hosts both semimetallic transport properties and a hybridization gap. The INS response exhibits momentum-dependent
magnetic excitations and a
spin-gap in the low-temperature Kondo coherent state, which electronic structure calculations corroborate as arising from the renormalized heavy band structure. Dynamical-mean field theory demonstrates that this renormalized band structure corresponds to a topological Kondo insulating state, and hence the INS probes bulk excitations of heavy topological bands. This identification of a Kondo
insulator addresses the long-standing mystery of the electronic properties of CeNiSn, and demonstrates the manifestation of a topological many-body coherent state in spectroscopic measurements of strongly correlated narrow band materials.
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All authors Xiaoying Zheng, Devashibhai T. Adroja, Hiroaki Kadowaki, Rajesh Sharma, Tanmoy Das, Seiko Ohira-Kawamura, Maiko Kofu, Zhaoyang Shan, Toshiro Takabatake, Huiqiu Yuan, Chao Cao, Michael Smidman
Mesoscale and Nanoscale Physics
Electrical driving of hole spin states in planar silicon MOS device by g-matrix modulation
Aaquib Shamim, Scott D. Liles, Joe Hillier et al. (+10 more)
Hole
spins in group IV
quantum dots are a highly promising way to develop CMOS compatible
spin qubits owing to their inherent
spin-orbit coupling, which enables fast, coherent, and electrical
spin control. However,
spin-orbit coupling not only enables multiple
spin-control mechanisms, but also exposes the
qubits to charge noise. In this work, we perform a systematic study of the
spin control mechanism in a planar silicon hole
quantum dot. We use g-
matrix formalism to discern contributions from the various
spin driving mechanisms and identify regions where
spins are less sensitive to charge noise. By mapping out the dependence of the Rabi frequency on the
magnetic field orientation, we observe the largest Rabi frequency in the in-plane direction and the smallest Rabi frequency close to the out-of-plane direction. These results enhance the understanding of how different mechanisms contribute to
spin driving within an industrially relevant architecture and aid in establishing the operating conditions for the rapid and coherent manipulation of hole
qubits.
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All authors Aaquib Shamim, Scott D. Liles, Joe Hillier, Jonathan Y. Huang, Isaac Vorreiter, Pratik Chowdhury, Chris C. Escott, Fay E. Hudson, Wee Han Lim, Kok Wai Chan, Rajib Rahman, Andrew S. Dzurak, Alexander R. Hamilton
Statistical Mechanics · Cross-listed from hep-lat
Tensor renormalization group approach to the $O(2)$ models via symmetry-twisted partition functions
Shinichiro Akiyama, Raghav G. Jha, Jun Maeda et al. (+2 more)
We investigate critical phenomena in the $O(2)$ models using
symmetry-twisted partition functions that can be efficiently computed within the tensor renormalization group framework. We first demonstrate, taking the three-dimensional model as an example, that
symmetry-twisted partition functions detect the spontaneous breaking of global continuous
symmetry. We then consider the same model in two dimensions, where the Berezinskii–Kosterlitz–Thouless (BKT) transition occurs. Since
symmetry-twisted partition functions directly provide the helicity modulus at a finite twist angle, we determine the BKT transition point. These results are presented based on Ref.~\cite{Akiyama:2026dzg}. Finally, in addition to the original paper~\cite{Akiyama:2026dzg}, we apply this approach to the two-dimensional generalized $O(2)$ model and confirm that it successfully identifies the phase transitions between the
ferromagnetic and nematic phases, as well as between the nematic and paramagnetic phases.
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All authors Shinichiro Akiyama, Raghav G. Jha, Jun Maeda, Yuya Tanizaki, Judah Unmuth-Yockey