Materials Science
Anisotropic Dopant and Strain Architectures in WS$_2$ Nanocrystals Driven by Growth Kinetics
Frederico B. Sousa, Raphaela de Oliveira, Matheus J. S. Matos et al. (+11 more)
Dopant distribution in two-dimensional
semiconductors is typically assumed to be
stochastic, limiting deterministic defect engineering. Here, we show that non-
equilibrium growth kinetics can be harnessed to define dopant-driven strain architectures in vanadium-doped WS$_2$ monolayers. Using synchrotron X-ray fluorescence, we identify preferential vanadium incorporation, anti-correlated with tungsten content, along crystallographic bisectors. An adsorption-growth-
diffusion model with a single kinetic parameter quantitatively captures the dopant segregation arising from preferential corner adsorption and limited
diffusion during chemical vapor deposition growth. Hyperspectral Raman imaging demonstrates mechanically induced vibrational responses, revealing localized tensile strain ($\varepsilon \approx0.70\%$) channels associated with the anisotropic dopant distribution. This regime is marked by the depletion of W-site-sensitive in-plane modes and the emergence of a localized $J2$ mode (210~cm$^{-1}$), which our ab-initio calculations attribute to antiphase V$-$V oscillations. These findings establish kinetic segregation as a route to deterministic chemical and strain architectures in 2D
semiconductors, enabling programmable defect landscapes and strain engineering during synthesis.
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All authors Frederico B. Sousa, Raphaela de Oliveira, Matheus J. S. Matos, Elizabeth Grace Houser, Igor Ferreira Curvelo, Zhuohang Yu, Mingzu Liu, Felipe Menescal, Gilmar Eugenio Marques, Leandro M. Malard, Mauricio Terrones, Bruno R. Carvalho, Helio Chacham, Marcio D. Teodoro
Superconductivity
Singular spin fluctuations in the strange-metal phase of La2-xSrxCuO4
B. Costarella, L. Soriano, I. Vinograd et al. (+8 more)
Although
spin fluctuations are central to the physics of high-Tc cuprates, their relevance to strange-metal behavior in the overdoped regime remains unclear. Here, we use high
magnetic fields to suppress superconductivity and an NMR protocol tailored to electronic inhomogeneity to show that the low-energy limit of the dynamical
spin susceptibility \chi”(q,omega) at x=0.25 in La2-xSrxCuO4 increases continuously down to our lowest temperatures. This behavior is suggestive of
quantum-critical fluctuations, a leading candidate mechanism for strange-metal transport, yet is observed well beyond the
spin-stripe critical doping x=0.19. Our data further reveal that the
spin dynamics are spatially inhomogeneous, suggesting that nanoscale electronic inhomogeneity may underlie this apparent paradox. These observations provide new insight into the electronic state from which strange-metal behavior emerges.
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All authors B. Costarella, L. Soriano, I. Vinograd, H. Mayaffre, S. Li, J. Yang, J. Luo, R. Zhou, G. Gu, J. M. Tranquada, M.-H. Julien
Mesoscale and Nanoscale Physics
Cryogenic microwave frequency combs based on quantum paraelectric superconducting resonators
Prasad Muragesh, Harikrishnan Sundaresan and Madhu Thalakulam
A frequency comb, known for its precision as an "optical ruler", features an evenly spaced spectral pattern. While these combs are vital in photonic
quantum technologies, their microwave counterparts are now highly sought after for cryogenic
quantum technologies, including semiconducting and superconducting
qubits and
quantum electrical metrology, which mainly operate in the microwave regime. However, microwave combs are still largely underexplored, and typically rely on complex, high-power optical systems incompatible with the low-power, cryogenic on-chip
quantum technologies. In this manuscript, we present an all-electrical, on-chip, cryogenic microwave frequency comb on Strontium Titanate (SrTiO$_3$), exploiting its Pockels-like effect in its
quantum paraelectric phase. Our device, utilizing a superconducting microwave cavity, generating the frequency comb via cavity phase modulation enabled by the field-induced effective $\chi(2)$ of SrTiO$_3$. The ability to continuously vary the dielectric constant of SrTiO$_3$ by the application of electric field, in its
quantum paraelectric phase, makes it possible to control the comb's operating frequency range. The exceptionally high dielectric constant of SrTiO$_3$, > 20,000 in its
quantum paraelectric state, enables an ultra-miniature design and on-chip integration with cryogenic
quantum technologies.
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Statistical Mechanics
Phase Ordering in a few O(n) Symmetric Models: Slow Growth, Mpemba Effect and Experimental Relevance
Wasim Akram, Nalina Vadakkayil, Sohini Chatterjee et al. (+1 more)
We study phase ordering dynamics in the three-dimensional nonconserved XY model, via Monte Carlo simulations, for quenches from paramagnetic phase to certain final temperatures $T_f$ within the
ferromagnetic region of the phase diagram. The growth in the system occurs via annihilation of
vortex and anti-
vortex pairs, cores of which, in the three dimensional system geometry, join from different planes, on which the
spins lie, to form line defects. In the long-time limit, the associated characteristic length scale, $\ell(t)$, appears to grow with time $(t)$ approximately as $t^{0.15}$, for $T_f=0$. The exponent is much smaller, like in the zero temperature intermediate time ordering in the three dimensional Ising model, than $1/2$, the expected value, that is realized for quenches to $T_f$ value that is sufficiently larger than zero. We carry out quenches from different starting temperatures, $T_s$, that lie above the critical temperature $T_c$. It is observed that the systems with higher $T_s$ approach the final
equilibrium faster. This resembles the puzzling Mpemba effect. We present similar results also from the simulations of the two- and three- dimensional Ising model. In the case of the 2D Ising model, we show that the Mpemba effect is observed only if the starting magnetization is restricted to a value close to zero. In $d=3$, on the other hand, for both the models, the effect appears even if the initial configurations at a given $T_s$ are chosen from the full distribution of magnetization. Thus, our results are of much experimental relevance.
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All authors Wasim Akram, Nalina Vadakkayil, Sohini Chatterjee, Subir K. Das
Mesoscale and Nanoscale Physics
Probing Floquet topological phases via non-Hermitian skin effect of reflected waves
Fangqiao Ye and Haiping Hu
Periodically driven systems host topological phases without static analogs, such as the anomalous Floquet phase characterized by trivial bulk bands yet robust boundary modes. In this work, we investigate the scattering problem of a Floquet Chern
insulator and reveal the non-Hermitian skin effect (NHSE) of reflected waves. Using a discrete-time scattering formalism, we demonstrate how the non-Hermitian winding number of the reflection
matrix is linked to the bulk Floquet invariant via boundary resonances. This reflected-wave NHSE relies on which quasienergy gap the incident wave resides in, leading to a gap-dependent Goos-Hänchen (GH) shift. We further show that the momentum-integrated GH shift quantitatively yields the Floquet topological invariant of the corresponding gap. Our work highlights a frequency-dependent NHSE of reflected waves in driven systems and provides a real-space scattering approach to identify non-
equilibrium topology.
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Soft Condensed Matter
Metastable Hyperuniformity at Discontinuous Absorbing Transitions
Yusheng Lei and Ran Ni
Nonequilibrium hyperuniformity can arise either as a steady-state property of driven active fluids or as a critical signature at continuous absorbing transition points in two and three dimensions. Whether analogous structural order exists near discontinuous absorbing transitions, and what mechanism generates it, remains unclear. Here, we show that discontinuous absorbing transitions generically host a metastable hyperuniform regime near the stability limit. Using a facilitated Manna model without center-of-mass conservation, we find anomalous scaling $S(k\to0)\sim k^{1.2}$, which appears only near the metastable regime and disappears both deep in the active phase and in the absorbing phase. This scaling is robust in both two and three dimensions, in contrast to critical hyperuniformity at continuous absorbing transitions. We further formulate a minimal conserved Reggeon field theory that reproduces the same metastable hyperuniform regime and anomalous scaling, demonstrating that the phenomenon does not rely on microscopic update rules but arises from the interplay of nonlinear activation, multiplicative demographic noise, and conserved diffusive fluctuations. These results identify metastable hyperuniformity as a generic pseudo-critical structural signature of discontinuous absorbing transitions coupled to a conserved density.
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Materials Science
Correlation-driven tunability of altermagnetism in RuO$_2$
Ina Park, Dongwook Kim, Inho Lee et al. (+3 more)
RuO$_2$ has been regarded as a prototypical candidate for metallic altermagnet, offering a potential platform for high-speed and high-efficiency spintronics. However, the
magnetic ground state of RuO$_2$ remains a topic of active debate due to conflicting experimental reports. In this work, we investigate the effect of electron correlations in RuO$_2$ using density functional theory combined with dynamical mean-field theory (DFT+DMFT). In contrast to previous DFT-based studies, DFT+DMFT captures essential dynamical correlation effects, yielding spectral functions and optical conductivities in excellent quantitative agreement with experiments, and further reveals that RuO$_2$ resides in the close vicinity of both the paramagnetic-altermagnetic phase boundary and the itinerant-localized crossover, rendering the
magnetic ground state highly susceptible to external perturbations. Indeed, even a minimal compressive strain of $\sim$0.5% is sufficient to drive the system into an altermagnetic phase. These findings elucidate the origin of the conflicting experimental observations and reveal that dynamical correlation effects are the key driving force behind the highly tunable
magnetic ground state of RuO$_2$.
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All authors Ina Park, Dongwook Kim, Inho Lee, Jisook Hong, Beomjoon Goh, Bo Gyu Jang
Statistical Mechanics
Emergence of information interference in stochastic systems with non-diagonal noise and switching environments
Andrea Marchetti, Daniel Maria Busiello and Giorgio Nicoletti
Stochastic forces in natural systems are rarely isotropic. From hydrodynamically coupled colloids to chemical reaction networks, noise contributions are inherently correlated. Together with internal interactions and changing environments, they shape the dependencies between the degrees of freedom of real-world systems, as quantified by their mutual information. In this work, we focus on linearized
stochastic systems with both non-diagonal noise
matrices and stochastically switching environments. We study how their presence leads to the emergence of information interference, so that the total mutual information cannot be decomposed as the sum of the contributions from deterministic interactions, noise anisotropy, and environmental switching alone. We identify two distinct sources of information interference: a static term, arising from the simultaneous presence of deterministic coupling and noise anisotropy; and a dynamic term, emerging from the interplay between internal processes and environmental switches. We then apply this framework to different physical systems. In the presence of switching temperatures, the mutual information disentangles exactly into internal and environmental contributions. When the noise anisotropy arises instead from hydrodynamic interactions, we find that the presence of a shared fluid can either mask or enhance the information stemming from a non-conservative force depending on its degree of non-reciprocity. Finally, in a fuel-driven chemical reaction network, we show that information interference is controlled by the non-
equilibrium driving. These results establish a general information-theoretic perspective on how anisotropic noise and environmental variability shape statistical dependencies in
stochastic systems.
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Materials Science
High-temperature behavior of amorphous alumina coatings: Insights from in-situ nanoindentation and X-ray diffraction studies
A. Zaborowska, L. Kurpaska, M. Zielinski et al. (+9 more)
Further development of
nuclear power plant technology relies heavily on materials durability under operating conditions. Estimating the materials performance in the operando tests is crucial. In this paper, the mechanical behavior of thin amorphous
nuclear-dedicated Al2O3 coatings deposited by pulsed
laser deposition was investigated by nanoindentation over the temperature range of 25-650C. Experimental nanomechanical analysis was supported by MD simulations. The results indicate that the hardness of the amorphous coating experiences a gradual, constant decrease with temperature, while the Young modulus value remains constant in the whole temperature range. Observed phenomena confirm the increasing plasticity of the material and it is postulated to be related to the bond-switching mechanism that accelerates at high temperatures. The post-mortem transmission electron microscopy characterization confirmed that the loaded material was non-crystalline over the entire range of the indentation temperatures. The thermal stability of the structure was further studied in-situ up to 1050C by X-ray diffraction. The implemented methodology allowed us to follow the dynamic process of phase transitions occurring in the material above 650C. First, thermally activated crystallization was observed at 700C. Intermediate alumina phases were present up to 950C, while above this temperature, exclusively the thermodynamically stable alpha-Al2O3 was observed. The in-situ high-temperature characterization of the
evolution of thin films boosts the understanding of the application limits of the coating systems at elevated temperatures. The added value is that the paper demonstrates the potential usefulness of combining high-temperature techniques to characterize the complete behavior of thin films at elevated temperatures.
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All authors A. Zaborowska, L. Kurpaska, M. Zielinski, Q. Xu, E. Wyszkowska, J. OConnell, J.H. Neethling, F. Di Fonzo, M. Frelek-Kozak, S. Papanikolaou, R. Diduszko, J. Jagielski
Statistical Mechanics
Beyond Explained Variance: A Cautionary Tale of PCA
Gionni Marchetti
We address shortcomings of principal component analysis (PCA) for visualizing high-dimensional data lying on a nonlinear low-dimensional
manifold via two-dimensional scatterplots, focusing on a fossil teeth
dataset from the early mammalian insectivore Kuehneotherium. While the PCA scatterplot reported by Jolliffe and Cadima (Philosophical Transactions of the Royal Society A, 2016) shows clustering in the region where PC2 < 0, our analysis based on t-SNE and persistent homology (PH) reveals a ring-like structure with no evident clustering and intrinsic dimensionality equal to one. We further propose a generative probabilistic-
geometric model in which the data are sampled uniformly from a unit circle. Under this model, pairwise cosine distances follow an arcsine distribution, in qualitative agreement with the observed U-shaped distribution, thereby independently supporting the analysis based on t-SNE and persistent homology.
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Statistical Mechanics
Quantifying information flow along a stochastic trajectory
Yongjae Oh, Euijoon Kwon and Yongjoo Baek
Stochastic information flow (SIF) quantifies information flow at the trajectory level, overcoming the limitations of conventional symmetric, ensemble-averaged measures. However, computational difficulties have hindered the empirical application of the SIF. In this work, we propose a scalable deep-learning method for estimating the SIF from general time-series data. Its applications to an exactly solvable two-particle model, Kuramoto oscillators, and empirical trajectories of interacting motile
cells demonstrate the utility of SIF as a data-driven indicator of cooperative structures.
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Statistical Mechanics
Theory of Rayleigh molecular light scattering by isotropic polar fluids revisited
P.M. Déjardin
The molecular theory of Rayleigh light scattering in dense isotropic polar fluids is reconsidered by suitably adapting local field concepts of electrostatics to propagating electromagnetic waves, hence accounting for both the rotational and dipole-induced dipole (DID) contributions. Simple analytical equations are derived for the various Rayleigh ratios relevant to lateral light scattering in various situations, namely pure DID, pure rotations and mixed contributions. For pure DID, the derived Rayleigh ratios are entirely analytical and very simple, while for pure rotation, the use of rotational mean field approximation is justified, hence allowing the description of Rayleigh ratios in terms of a single orientational correlation parameter that is straightforwardly determined as a positive root of a quadratic algebraic equation. Simple expressions for the Rayleigh ratios are also derived in two mixed situations where DID dominates rotation and when rotation dominates DID. Relation to previous experimental and theoretical work is discussed.
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Quantum Gases
Site-selective preparation of two-dimensional dipolar quantum gases in an optical beat-note lattice
Niclas Höllrigl, Marian Kreyer, Rudolf Grimm et al. (+1 more)
High-resolution microscopy of two-dimensional dipolar
quantum gases requires selecting individual atomic layers, a task complicated for strongly
magnetic lanthanide atoms by the limited applicability of standard
magnetic-gradient techniques. We present an all-optical method for the deterministic spatial selection of single- and
bilayer samples of cold dipolar atoms using spatially selective parametric heating within a beat-note superlattice. By utilizing a high-resolution microscope objective as a common retroreflector for both optical frequency components, the
lattice planes are passively stabilized. This renders their positions exceptionally robust against experimental drifts and structure-borne vibrations, even eliminating the need for active
laser stabilization over millimeter-scale separations from the reflecting surface. We validate this approach by demonstrating the robust isolation of one or two atomic layers in precise coincidence with the focal plane of our objective. This enables future single-atom-resolved studies of long-range interacting systems.
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All authors Niclas Höllrigl, Marian Kreyer, Rudolf Grimm, Emil Kirilov
Other Condensed Matter
Space-Charge-Driven Nonlinear Charge Transport in Silicon Reconfigurable Nonlinear-Processing Units
Jonas Kareem, Lorenzo Cassola, Reinier J.C. Cool et al. (+4 more)
Reconfigurable nonlinear-processing units (RNPUs) are multi-terminal electronic devices that act as computational primitives, exploiting intrinsic nonlinear charge transport combined with electrostatic tunability. Silicon-based realizations provide a scalable and technologically relevant platform toward unconventional computing hardware, yet the physical origin of their room-temperature nonlinearity has remained unresolved. Here, we demonstrate room-temperature operation in both boron- and arsenic-doped silicon RNPUs and show, using temperature- and length-dependent measurements supported by TCAD simulations, that charge transport is governed by space-charge effects. Interface trap states strongly suppress the
equilibrium carrier density, while the functional nonlinearity arises from the competition between injected carriers and ionized dopants. The resulting transport evolves from Ohmic to strongly nonlinear and space-charge-limited current regimes, as evidenced by voltage and length scaling. The opposite-polarity background doping is shown to control the onset and strength of the nonlinearity, producing behavior beyond the quadratic dependence of the classical Mott-Gurney law. Agreement between experiment and simulation supports that the spatial distribution of injected carriers and fixed charge governs the electric-field profile and device response. These results establish a space-charge-based framework for RNPUs that does not require disorder or hopping transport, and provide design guidelines for scalable, CMOS-compatible nonlinear computing hardware.
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All authors Jonas Kareem, Lorenzo Cassola, Reinier J.C. Cool, Janiek I. van Slooten, Ray J.E. Hueting, Peter A. Bobbert, Wilfred G. van der Wiel
Materials Science
Multiple Softening Q-vectors Driving a Cascade of CDW Phases in $\mathrm{1T-VSe}_{2}$
Zheng-Hong Li, Yung-Ting Lee, Yu-Chan Tai et al. (+8 more)
Charge density wave (CDW) formation in two-dimensional materials is governed by complex competing
lattice instabilities that remain incompletely understood. Here, we investigate the structural
evolution of monolayer $\mathrm{1T-VSe}_{2}$ using first-principles electronic and
phonon calculations. The pristine phase exhibits several imaginary-frequency
phonon modes associated with dominant instability wave vectors $\mathrm{Q}_{CDW}$, which generate the first-generation CDW phases. Subsequent
phonon analyses reveal that several of these intermediate structures remain dynamically unstable and undergo further
symmetry-lowering distortions into larger superstructures. Through iterative
phonon-driven relaxations, we identify multiple transformation pathways that converge toward the same low-energy $2\sqrt{3}\times4$ CDW configuration. Although these pathways originate from distinct intermediate CDW states, they ultimately reach nearly degenerate energetically stable phases, demonstrating that different
phonon-driven routes can lead to the same ground-state configuration. The results establish a unified
phonon-driven cascade mechanism for hierarchical CDW formation in monolayer $\mathrm{1T-VSe}_{2}$ and provide a systematic framework for understanding competing ordered phases in low-dimensional
quantum materials.
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All authors Zheng-Hong Li, Yung-Ting Lee, Yu-Chan Tai, Cheng-Tien Chiang, Chien-Cheng Kuo, Meng-Kai Lin, Chun-Liang Lin, Hung-Chung Hsueh, Ming-Chiang Chung, Po-Tuan Chen, Chi-Cheng Lee
Strongly Correlated Electrons
A thermodynamic reference for field-induced phenomena in $\alpha$-RuCl$_3$: two coexisting polymorphs account for multiple magnetic phase transitions
Hamza Nasir, Daniel Balazs, Muhammad Nauman et al. (+5 more)
The majority of research on $\alpha$-RuCl$_3$ has focused on applying in-plane
magnetic fields to suppress the
antiferromagnetic order and induce a
quantum spin liquid (QSL). However, interpreting field-induced phenomena has been complicated by the material's temperature- and sample-size-dependent
crystal structure and its sensitivity to strain-induced stacking disorder. Here, we isolate the monoclinic ($C2/m$) phase in nanogram-scale single
crystals, providing the opportunity to study Kitaev physics in a new setting. We perform high-resolution magnetotropic susceptibility measurements on a structurally well-defined
crystal within several
crystal planes. Mapping the
antiferromagnetic (AFM) phase boundary as a function of temperature,
magnetic field, and field orientation, we find that the monoclinic phase diagram closely resembles that of rhombohedral
crystals, but is systematically shifted to higher transition temperatures and critical fields. We find that the critical fields coincide quantitatively with anomalies observed across the $\sim$7-11~T field range, where Kitaev
spin liquid physics has been widely reported across numerous independent studies and experimental techniques. Our study shows that these anomalies arise from the
magnetic phase boundaries of coexisting monoclinic and rhombohedral structural domains, rather than an exotic phase. These results provide a thermodynamic reference against which past studies can determine their structural composition, and toward which future studies can look for genuine signatures of
spin-
liquid phenomena beyond the close vicinity of the AFM boundary under in-
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All authors Hamza Nasir, Daniel Balazs, Muhammad Nauman, Vikram Nagarajan, Ezekiel Horsley, Subin Kim, Young-June Kim, K. A. Modic
Materials Science
From Film to Flakes: Electronic Properties and Magnetization Variations in Yttrium Iron Garnet
Pia M. Düring, Seema, Roman Hartmann et al. (+7 more)
Yttrium iron garnet (YIG) is a ferrimagnetic
insulator valued for its high Curie temperature, very low
magnetic damping, and ability to support long-range
spin-wave transport. These qualities have established it as a cornerstone material in the field of spintronics and magnonics. Most studies on YIG so far have been focused on bulk
crystals, thin films, and nanoparticles, including variants with substitutions at the yttrium or iron site. New morphologies such as sub-micron flakes have drawn interest recently as their geometry and mechanical flexibility might enable different device architectures. However, detailed investigations combining their electronic structure and
magnetic behavior remain scarce. In this work, we present a comparative study of the electronic and
magnetic properties of a bulk-like YIG film and a sub-micron-sized YIG flake. Our results highlight the distinct behavior that emerges in sub-micron dimensions and point toward future uses for flake-based YIG in compact spintronics devices.
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All authors Pia M. Düring, Seema, Roman Hartmann, Sebastian Sailler, Michaela Lammel, Andrei Gloskovskii, Christoph Schlueter, Angelo Di Bernardo, Sebastian T. B. Goennenwein, Martina Müller
Strongly Correlated Electrons · Cross-listed from quant-ph
Universal Design and Physical Applications of Non-Uniform Cellular Automata on Translationally Invariant Lattices
Xiang-You Huang, Jie-Yu Zhang and Peng Ye
Motivated by recent theoretical and experimental advances,
hyperbolic lattices have emerged as a paradigmatic setting in which geometry becomes an active organizing principle of
quantum systems. Their negative
curvature, exponential volume growth, and non-Abelian translation
symmetry make them fundamentally distinct from Euclidean
lattices and give rise to rich geometry-dependent physics, but also hinder the direct application of well-established analytical and computational approaches originally developed for physical systems defined on Euclidean
lattices. To establish a unified framework for geometry-dependent physics on Euclidean and
hyperbolic lattices, we develop higher-order non-uniform cellular automata (NUCA) as a local-to-global construction for translationally invariant regular
lattices. This construction derives geometry-dependent update rules through a
lattice-deforming procedure that embeds
hyperbolic lattices into a Euclidean square
lattice, thereby encoding
hyperbolic geometry while preserving physical locality. It thus provides a systematic route toward
quantum and classical physics on
hyperbolic lattices. We demonstrate the framework in three applications ranging from
quantum many-body physics to non-
equilibrium statistical physics. First, on the
hyperbolic $\{5,4\}$
lattice, a linear NUCA generates exactly solvable subsystem
symmetry-protected topological (SSPT) models and spontaneous subsystem
symmetry-breaking models. Second, as a
quantum generalization, we construct non-uniform Clifford
quantum cellular automata (CQCA) for the
hyperbolic cluster state. Third, we formulate a probabilistic NUCA for directed percolation (DP) on the
hyperbolic lattice.
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Mesoscale and Nanoscale Physics
An Effective Scaling Framework for Non-Adiabatic Mode Dynamics
A.M.Tishin
This study proposes an effective theoretical framework for non-adiabatic parametric excitation in structured media, incorporating a nonlinear frequency regulator U as a stabilizing mechanism. We introduce the non-adiabaticity parameter as a time-local diagnostic for driven non-stationary systems and analyze its competition with nonlinear spectral detuning through the scaling ratio. The principal physical result is that strongly nonlinear oscillatory systems can exhibit saturation of non-adiabatic parametric amplification: when the nonlinear regulator becomes sufficiently strong, exponential mode growth is dynamically suppressed and the excitation evolves toward a bounded low-occupancy regime. Using numerical verification in an expanded 100-level bosonic Fock basis, we demonstrate a crossover from
hyperbolic amplification dynamics toward an effectively bounded response associated with spectral blockade and suppression of higher-order mode occupation. These results suggest that nonlinear spectral stabilization may represent a general mechanism for finite-amplitude non-adiabatic dynamics in driven structured media.
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Strongly Correlated Electrons
Invertible Symmetry and Spontaneous Duality Breaking in the Transverse-Field Ising Model
José Dupont and Jasper van Wezel
The self-duality of the transverse-field Ising model is an archetype for dualities that, alongside
symmetry and
topology, are used as an organizing principle throughout modern physics. This duality, however, is not exact. The original and dual models have different
symmetries and numbers of ground states, and the duality is implemented by a non-invertible operator giving rise to a non-invertible
symmetry at the
quantum critical point. Here, we show that by adjusting the model to accommodate open rather than periodic boundary conditions, it allows for an exact duality implemented by a unique invertible operator. In the model with exact duality, the
symmetry at the
quantum critical point is also exact, and hence invertible. Moreover, we find that the exact duality necessitates the presence of an anomalous edge degree of freedom, thus realizing a duality rather than
topology based bulk-boundary correspondence. Finally, the exactness of the duality implies that the spontaneous breakdown of a global
symmetry in terms of the original model can equivalently be described as spontaneously breaking a local
symmetry in the dual system. We show that this seeming contradiction of Elitzur's
theorem can be explained by the original and dual models obtaining different sensitivities to spatially local perturbations in any physical implementation of the
Hamiltonian. Although the dual partners are mathematically equivalent, their physical implementations therefore are not. In analogy to the spontaneous breakdown of
symmetries, we term this emergent distinction due to arbitrarily small environmental influences spontaneous duality breaking.
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Mesoscale and Nanoscale Physics
Lamb Shift of Landau Levels in Two-Dimensional Electron Systems in a Multimode Resonator
Aleksandr Shabanov, Georgy Alymov and Dmitry Svintsov
The use of resonators to modify the behavior of electromagnetic systems demonstrates its potential for application in a wide range of problems. However, existing theoretical studies often resort to the single-mode approximation, rarely considering a second resonator mode. In this paper, we show that including a large number of resonator modes in the model significantly enhances the softening effect of the cyclotron frequency of a two-dimensional electron system. We address this problem by demonstrating the possibility of reducing the system to a set of coupled harmonic oscillators and finding the eigenfrequencies of the oscillators. This is made possible by applying the self-energy method for modes in one polarization and the method for finding the
eigenvalues of
matrices that have undergone first-rank updating for modes in the perpendicular polarization.
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Mesoscale and Nanoscale Physics
Thermoelectric enhancement from an asymmetric spectral-conductivity cusp in spin-1 chiral fermions
Risako Kikuchi, Junya Endo and Ai Yamakage
A recent study showed that, in
spin-1
chiral fermion systems composed of two linearly dispersing bands and one trivial band,
impurity scattering produces an asymmetric cusp in the spectral conductivity. We demonstrate that this asymmetric cusp markedly enhances the electronic thermoelectric response. Using linear-response theory within the self-consistent Born approximation, we find low-temperature enhancements in both the Seebeck coefficient and the electronic figure of merit. Increasing the
curvature of the trivial band further strengthens this cusp-induced enhancement, even though the corresponding density of states becomes smoother. To clarify this mechanism, we introduce a minimal cusp model for the spectral conductivity and show that the enhancement is most pronounced when the cusp is sharp and strongly asymmetric, and when the spectral conductivity at the cusp energy is small.
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Superconductivity
Interface controlled spin filtering and nonreciprocal transport in Altermagnet/Ising superconductor junctions
Arindam Boruah, Saumen Acharjee and Prasanta Kumar Saikia
We investigate theoretically
spin-resolved transport,
spin filtering, and nonreciprocal effects in an Altermagnet/Ising
superconductor (AM/ISC) junction with a
spin-active interface. Using a modified Bogoliubov-de Gennes framework within the scattering formalism, we demonstrate that the interplay among intrinsic
spin-orbit coupling (ISOC), anisotropic AM
spin texture and
spin-dependent interfacial scattering gives rise to strongly anisotropic charge and
spin conductance. In the weak
spin-mixing regime, transport remains predominantly helicity conserving and exhibits pronounced angular dependence governed by the relative orientation between the AM
spin texture and interface magnetization. Increasing ISOC enhances
spin conductance and leads to
spin-selective Andreev reflection resulting in finite
spin filtering. In contrast, the strong
spin-mixing regime exhibits enhanced angular anisotropy and robust
spin-polarized transport over a broad energy range. Conventional Andreev reflection becomes strongly suppressed, accompanied by substantial spectral redistribution. We further show that nonreciprocal transport persists throughout the single-band, intermediate and double-band ISC regime. The
spin polarization and
spin-filter efficiency exhibit nonmonotonic dependence on system parameters, reaching values up to $\sim 86\%$, with characteristic angular modulation determined by the AM
spin texture. Finite-energy analysis reveals enhanced
spin selectivity at low energies and suppression near the superconducting gap. Furthermore, strong
spin mixing at the AM/ISC junction produces asymmetric conductance patterns, indicating nonreciprocal transport. Our results establish AM/ISC junctions as a versatile platform for tunable superconducting spintronics and directional
spin transport.
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Mesoscale and Nanoscale Physics
Reconfigurable chiral superconductivity
Surajit Dutta, Nadav Auerbach, Tonghang Han et al. (+9 more)
Rhombohedral multilayer
graphene at high displacement fields hosts superconductivity emerging from a
spin valley polarized quarter metal, with transport signatures suggestive of time reversal
symmetry (TRS) breaking and
chiral superconductivity (CSC). These observations have motivated proposals of topological superconductivity and non-Abelian quasiparticles, yet direct
magnetic evidence and microscopic insight into the superconducting state remain lacking, limiting understanding of this unique state. Here we use nanoscale SQUID on tip magnetometry to image isospin-polarized domains in rhombohedral pentalayer
graphene and establish CSC via spatially resolved thermodynamic detection of TRS breaking. We find that the density at which domain walls proliferate at elevated temperatures coincides with the onset of CSC, indicating an underlying transition in the parent state that both induces superconductivity and reduces domain wall energy. We further show that the
chiral domain structure in the superconducting phase is inherited from the isospin-polarized parent state. Strikingly, the CSC phase exhibits multiple transport regimes governed by configurations of
chiral domains separated by highly resistive domain walls. We demonstrate deterministic, ultra low current control of these domains, enabling reversible switching between states of opposite chirality a defining CSC property absent in other
superconductors. These results establish rhombohedral
graphene as a unique platform for reconfigurable CSC and ultra low power electronic functionality based on controllable isospin textures.
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All authors Surajit Dutta, Nadav Auerbach, Tonghang Han, Yaozhang Zhou, Gal Shavit, Niladri-Sekhar Kander, Yuri Myasoedov, Martin E. Huber, Kenji Watanabe, Takashi Taniguchi, Long Ju, Eli Zeldov
Mesoscale and Nanoscale Physics
Electron - acoustic phonons scattering in quantum wells in a tilted quantizing magnetic field
M.P. Telenkov and Yu.A. Mityagin
Electron scattering by longitudinal acoustic
phonons in a quantizing
magnetic field is considered. Expressions for the scattering rate in a
magnetic field tilted to the
quantum well layers are derived. By analyzing these expressions, trends in the behavior of the scattering rate are established with changes in the
magnetic field strength and orientation, as well as the potential profile of the
quantum well.
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Strongly Correlated Electrons
Reentrant behavior and possible $2/3$ magnetization plateau on the double-trillium langbeinite K$_2$Ni$_2$(SO$_4$)$_3$
Matías G. Gonzalez, Yurii Skourski, Johannes Reuther et al. (+1 more)
K$_2$Ni$_2$(SO$_4$)$_3$ is a member of the langbeinite family, consisting of two intertwined $S=1$ trillium
lattices, out of which one is strongly coupled (strong-TL) and the other is weakly coupled (weak-TL). Further inter-trillium interactions give rise to a highly-frustrated Heisenberg
Hamiltonian. Despite ordering at low temperatures, K$_2$Ni$_2$(SO$_4$)$_3$ lies close in parameter space to a
spin-
liquid region that surrounds the tetratrillium limit, where each triangle belonging to strong-TL turns into a tetrahedron by connecting to a single
spin from weak-TL. Here, we compare the experimentally determined magnetization process using pulsed
magnetic fields up to $40$ T with classical Monte Carlo calculations, uncovering a series of phase transitions at both low and intermediate fields. Furthermore, we reveal a signature of a $2/3$ magnetization plateau consisting of a $1/3$ phase on strong-TL and a fully polarized phase on weak-TL. Although in the classical limit no plateau is expected, we find a very prominent dome structure reflecting the tendency of the system to stabilize this particular
spin configuration. The presence of a dome leads to a reentrant phenomenon in which the system recovers the
Hamiltonian symmetries when increasing the
magnetic field. Finally, we show that this plateau-like phase is also present in the classical Heisenberg model on the single trillium and tetratrillium
lattices, indicating its possible presence in the large family of double-trillium langbeinite compounds. Our findings motivate future studies on the presence of the plateau phase in the
quantum limit of both trillium and double-trillium materials within the langbeinite family.
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All authors Matías G. Gonzalez, Yurii Skourski, Johannes Reuther, Ivica Živković
Superconductivity
Superconductivity in a Two-Orbital Hatsugai-Kohmoto Model at Half Filling
Nico Hahn and R. Matthias Geilhufe
Multiband superconductivity gives rise to a rich landscape of possible pairing states. Here we study superconductivity emerging from a half-filled normal state in a two-orbital extension of the Hatsugai-Kohmoto model, an exactly solvable model of correlated electrons with momentum-local interactions, which provides a minimal framework to explore the interplay of strong correlations, orbital structure and pairing
symmetry. For a system with point-group
symmetry $\rm D_{4h}$, we classify the
symmetry-allowed superconducting gap structures, taking into account
spin, orbital and momentum degrees of freedom. We further compute the critical temperature and the superconducting order parameter for selected pairing channels as functions of interaction and pairing strength within a mean-field treatment. Our results provide a systematic framework for analyzing superconductivity in the orbital Hatsugai-Kohmoto model and extend
symmetry-based approaches to correlated multiband settings.
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Superconductivity · Cross-listed from physics.app-ph
In-situ tunable superconducting diode: towards field-free operation with infinite nonreciprocity
Razmik A. Hovhannisyan, Taras Golod, Amirreza Lotfian et al. (+1 more)
Efficient, scalable, and
magnetic-field-free superconducting diodes are essential for future superconducting electronics; yet, despite significant efforts, such practical devices remain unrealized. The main challenge lies in achieving broad-range in-situ tunability, both for optimization and for achieving transistor-like operation. Here, we study diodes based on four-terminal niobium planar Josephson junctions. We show that the multiterminal structure eliminates the need for an external
magnetic field and enables essentially unrestricted in-situ tunability, along with reconfigurability of the diode polarity, leading to new functionality. For example, we demonstrate that such diodes can operate as Gauss
neurons via reentrant superconductivity. By deliberately tuning the junction parameters, we obtain effectively infinite nonreciprocity (within experimental resolution) leading to threshold-free ac-current rectification. Such technologically simple, reconfigurable, and broadly tunable diodes could be instrumental for future digital and neuromorphic computing.
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All authors Razmik A. Hovhannisyan, Taras Golod, Amirreza Lotfian, Vladimir M. Krasnov
Materials Science
Minimum energy paths for defect annihilation in finite dodecagonal quasicrystal clusters
Tiejun Zhou, Rong Liu, Gang Cui et al. (+3 more)
Defect repair in quasicrystals involves local structural rearrangements on a complex potential energy landscape. Here, we combine the string method with the spring pair method to compute a minimum energy path connecting a locally defective finite dodecagonal quasicrystal cluster to a locally repaired reference configuration in the Lennard-Jones–Gauss particle model. The computed path contains seven local minima connected through six transition states. A detailed analysis of one defective region resolves three successive stages: a phason flip, aggregation of neighboring shield-like defects, and decomposition of the aggregated motif. The phason flip restores the local outer-ring structure and relocates a shield-like defect into the interior. Subsequent collective rearrangements remove the defective motifs and yield a net decrease in the local interaction-energy measure together with an increase in local bond-orientational order. These results provide a microscopic description of a specific defect-repair pathway on the potential energy surface of a finite dodecagonal quasicrystal cluster.
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All authors Tiejun Zhou, Rong Liu, Gang Cui, Xianbo Huang, Li Peng, Kai Jiang
Materials Science · Cross-listed from physics.class-ph
Acoustic Chirality
Alex J. Vernon and Konstantin Y. Bliokh
We reveal a previously unknown continuous
symmetry and conservation law in the equations of linear isotropic elasticity, which describe the chirality of elastic waves. We show that the integral chirality is determined by the population imbalance between right- and left-handed transverse
phonons, whereas the local chirality density generally involves both transverse and longitudinal wave components. We also introduce the related concepts of acoustic helicity and “false chirality”. The theory is illustrated with simple interference fields exhibiting distinct distributions of chirality,
spin angular momentum, and false chirality. Our results establish chirality as a fundamental property of elastic waves and provide a general theoretical framework for
chiral acoustic phenomena.
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