Strongly Correlated Electrons
Non-Hermiticity Induced Universal Anomalies in Kondo Conductance
Wei-Zhu Yi, Yun Chen, Jun-Jun Pang et al. (+3 more)
Strong correlation, when combined with dissipation in open systems, can lead to a variety of exotic
quantum phenomena. Here, we study nontrivial interplays between non-
Fermi liquid behaviors emerging from strong correlation and non-Hermiticity arising from open systems. We propose a practical physical setup that realizes a non-Hermitian multichannel Kondo model. We identify a weak-coupling local moment fixed point and a strong-coupling non-
Fermi liquid fixed point under PT
symmetry, both are enriched by the non-Hermitian effect. Remarkably, universal unconventional Kondo conductance behaviors are found for both cases, which are distinct from all previously studied Kondo systems. Particularly, we show that an anomalous upturn of conductance could take place with increasing the temperature, originating from the interplay between non-
Fermi liquid and non-Hermiticity. Our results identify a novel class of transport phenomena unrecognized before, driven by intertwined effects of correlation and dissipation.
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All authors Wei-Zhu Yi, Yun Chen, Jun-Jun Pang, Hong Chen, Baigeng Wang, Rui Wang
Materials Science
Tuning magnetic, lattice, and transport properties in CoNb3S6 via Fe doping
Deepu Kumar, Joydev Khatua, Mukesh Suthar et al. (+9 more)
We present a comprehensive investigation of the effects of Fe doping on the
lattice dynamics,
magnetic ordering, and magneto-transport properties of the intercalated van der Waals antiferromagnets Co1-xFexNb3S6 (x = 0.1 and 0.3). Temperature- and polarization-dependent Raman scattering measurements reveal a pronounced blue shift of the 180 cm-1
phonon mode with increasing Fe concentration, indicating enhanced sensitivity of
lattice vibrations to Fe-induced structural and mass effects. While the temperature
evolution of the
phonon modes is dominated by conventional anharmonic
phonon softening, subtle anomalies observed near the Néel temperature for x = 0.1 point to weak
spin-
phonon coupling. Electrical transport and
magnetic susceptibility data show clear signatures of the
antiferromagnetic phase transitions at TN ~ 20.5-23.7 K for x = 0.1 and TN ~ 32.0 K for x = 0.3. Out-of-plane magnetization measurements reveal hysteretic behavior with two field-induced transitions for x =0.1, which evolve into a single hysteresis loop at x =0.3, signaling a subtle reconstruction of the
magnetic ground state. Magneto-transport measurements for x = 0.1 further display a butterfly-shaped hysteretic magnetoresistance and a weak topological
Hall effect; however, both features are strongly suppressed at x = 0.3. These results illustrate the critical role of Fe-induced
magnetic structure reconstruction in fine-tuning topological and
magnetic transport phenomena in intercalated van der Waals antiferromagnets.
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All authors Deepu Kumar, Joydev Khatua, Mukesh Suthar, Rajesh Kumar Ulaganathan, Jeonghun Kang, Hengbo Cui, Sihun Seong, Seo Hyoung Chang, Kee Hoon Kim, Raman Sankar, Maeng-Je Seong, Kwang-Yong Choi
Statistical Mechanics · Cross-listed from hep-th
Defect relative entropy in symmetric orbifold CFTs
Mostafa Ghasemi
In this work, we compute the defect relative
entropy between topological defects in the symmetric product orbifold CFT $\mathrm{Sym}^N(M) = M^{\otimes N}/S_N$. Our analysis covers two distinct classes of defects: universal defects, which realize the $\mathrm{Rep}(S_N)$ non-invertible
symmetry, and non-universal defects. We show that the defect relative
entropy reduces to a Kullback–Leibler (KL) divergence. The resulting expression decomposes naturally into two contributions: one governed by characters of the symmetric group $S_N$, and the other controlled by modular $S$-
matrix elements of the seed RCFT. Remarkably, both sets of data appear as probability distributions, yielding an information-theoretic interpretation of permutation group data and modular data within the symmetric orbifold. The structure of the divergence depends sensitively on the defect class. For universal defects, only the permutation group data contributes; for maximally fractional defects, both permutation and modular data enter and together define the relevant probability distributions. This feature suggests that the maximally fractional defect can be understood as a kind of product of the RCFT defect and the symmetric orbifold defect.
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Quantum Gases
Measuring Spin-Charge Separation by an Off-diagonal Dissipative Response
Liang Tong, Shi Chen and Yu Chen
Fractionalization of
symmetry - exemplified by
spin-charge separation in the 1D Hubbard model and fractional charges in the fractional
quantum Hall effect - is a typical strongly correlated phenomena in
quantum many-body systems. Despite the success in measuring velocity differences, however, it is still quite challenging in probing emergent excitations' anomalous dimensions experimentally. We propose a off-diagonal dissipative response protocol, leveraging dissipative response theory (DRT), to directly detect
spin-charge separation. By selectively dissipating
spin-$\downarrow$ particles and measuring the
spin-$\uparrow$ response, we uncover a universal temporal signature: the off-diagonal response exhibits a crossover from cubic-in-time ($t^3$) growth at short times to linear-in-time ($t$) decay at long times. Crucially, the coefficients $\varkappa^s$ (short-time) and $\varkappa^l$ (long-time) encode the distinct anomalous dimensions and velocities of spinons and holons, providing unambiguous evidence of fractionalization. This signal vanishes trivially without
spin-charge separation. Our predictions, verified numerically via tDMRG, with microscopic parameters linking with Luttinger parameters by Bethe ansatz, establish off-diagonal dissipative response as a probe of
quantum fractionalization in synthetic
quantum matter.
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Materials Science
Relativistic spin-momentum locking in ferromagnets
Xujia Gong, Amar Fakhredine and Carmine Autieri
The relativistic
spin-momentum locking has been proven in time-reversal-breaking classes of materials with zero net magnetization in the non-relativistic limit, such as altermagnets and other non-collinear magnets. Using density functional theory calculations, we aim to show relativistic
spin-momentum locking in ferromagnets, focusing on a broad class of
ferromagnetic materials with
magnetic sites connected by rotational
symmetry, and compare with fcc Ni. In SrRuO3, the antisymmetric exchange interaction produces a
spin canting orthogonal to the easy axis, while in all other cases,
spin canting is forbidden. Even when the canted
magnetic moment in real space is forbidden, relativistic
spin-momentum locking shows sizable contributions in k-space. Using prototypical ferromagnets such as orthorhombic SrRuO3, hexagonal CrTe and CrAs with the NiAs
crystal structure, half-Heusler MnPtSb, and fcc Ni, we demonstrate that relativistic
spin-momentum locking can generate strong effects in ferromagnets. Subdominant components of centrosymmetric ferro-
magnetic materials with
magnetic sites connected by rotational
symmetry host
spin-momentum locking similar to altermagnets, while noncentrosymmetric MnPtSb hosts relativistic p-wave due to the
spin-orbit coupling. Fcc Ni shows a more complex behavior with a combination of two
spin-momentum locking patterns characteristic of altermagnets. Because ferromagnets typically have larger bandwidths than altermagnets, they provide a promising platform for observing even-wave relativistic
spin-momentum locking and associated emergent phenomena. From an application standpoint, relativistic
spin-momentum locking governs
symmetry-allowed
spin Hall currents,
spin photocurrents, and other momentum-dependent
spin responses in k-space.
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Statistical Mechanics
Finite-time Polytropic Steering Reveals Non-monotonic Irreversibility
Cong Fu, Youhui Lin, Shanhe Su et al. (+1 more)
How irreversibility evolves from slow to fast driving is a central question in nonequilibrium thermodynamics. While near-
equilibrium theory predicts increasing irreversibility with driving speed, the corresponding crossover far from
equilibrium is not generally resolved within a unified control framework. Here we introduce polytropic steering, in which a prescribed relation between the ensemble energy and a time-dependent control parameter continuously organizes finite-time processes between isothermal and adiabatic limits. A Fokker-Planck formulation makes the construction applicable to general confining potentials, and yields closed-form thermodynamic expressions for a harmonic trap. We find a non-monotonic irreversibility: the
entropy generation decreases in both the quasistatic and fast-driving limits and exhibits a maximum at an intermediate protocol duration. The resulting most-irreversible timescale quantifies the competition between thermal relaxation and external driving. We verify the persistence of this behavior in an anharmonic optical-
lattice potential and demonstrate how the same steering principle controls power-efficiency trade-offs in finite-time Brownian engines.
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All authors Cong Fu, Youhui Lin, Shanhe Su, Yu-Han Ma
Mesoscale and Nanoscale Physics
Coulomb Interaction and Density-Independent Exciton-Scattering Processes in Atomically Thin Semiconductors
Henry Mittenzwey, Andreas Knorr and Thorsten Deilmann
In
quantum-kinetic approaches to the dynamics of Coulomb-bound many-body correlations such as
excitons, trions, biexcitons or higher-order correlations, a detailed knowledge of the many-body Coulomb
Hamiltonian serving as a starting point is important. In this manuscript, the second-quantized description of the Coulomb interaction between Bloch electrons in a Heisenberg-equation-of-motion approach in atomically thin
semiconductors is derived and reviewed. Emphasis is put on a discussion of Umklapp processes and the dielectric screening including all local-field effects. A link between ab initio methods of screening and few-band models in effective-mass approximations for the
quantum kinetics is established and important Coulomb scattering processes contributing to the
exciton energy landscape and density-independent
exciton scattering are discussed.
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Strongly Correlated Electrons
Interplay between non-Fermi liquid and non-Hermiticity: A multi-method study of non-Hermitian multichannel Kondo model
Wei-Zhu Yi, Yun Chen, Jun-Jun Pang et al. (+3 more)
Non-Hermitian multichannel Kondo problems host both non-
Fermi liquid and non-Hermitian physics, which provide a prototypical model to explore exotic collective
quantum phenomena driven by the two different ingredients. Here, we first propose an experimental setup that realizes this model with exact channel
symmetry as well as a controllable PT
symmetry. Then, we perform a multi-method study of this model, focusing on the low-energy spectrum, the thermodynamic quantities, and the transport properties associated with different fixed points. Using the Bethe ansatz approach, we identify existence of the Yu-Shiba-Rusinov-like state previously found in the non-Hermitian single-channel Kondo model. Then, based on non-Hermitian numerical renormalization group calculations, we reveal clear numerical signatures of the Yu-Shiba-Rusinov state emerging in the relatively strong non-Hermiticity regime of the PT-asymmetric model. Furthermore, our boundary conformal field theory, which is found to be applicable for the PT-symmetric model, uncovers an anomalous temperature dependence of the Kondo conductance, which is beyond conventional Hermitian Kondo systems.
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All authors Wei-Zhu Yi, Yun Chen, Jun-Jun Pang, Hong Chen, Baigeng Wang, Rui Wang
Materials Science
MLIP-MC: A Framework for Adsorption Simulations using Machine-Learned Interatomic Potentials
Connor W. Edwards, Fengxu Yang, Konstantin Stracke et al. (+1 more)
Grand canonical Monte Carlo (GCMC) simulations are essential for screening metal-organic frameworks (MOFs) for gas adsorption, yet their accuracy is limited by underlying interatomic potentials. Universal machine-learned interatomic potentials (MLIPs), trained on diverse chemical
datasets, promise zero-shot prediction without system-specific training. We introduce MLIP-MC, an open-source Python framework to conduct GCMC simulations with MLIPs, and use this framework to
benchmark a series of universal models, including MACE-MP-0, ORB-v3, and fairchem ODAC, for CO2 adsorption on ZIF-8, ZIF-4, and Mg-MOF-74. All universal models exhibit systematic biases, consistently over- or underestimating adsorption energetics. Crucially, accuracy depends on training data composition: only models trained on MOF-adsorbate interactions achieve reasonable agreement with a density functional theory derived reference. Errors grow linearly with CO2 uptake, reflecting compounding inaccuracies in adsorbate-adsorbate interactions. Our results demonstrate that current universal MLIPs require finetuning for quantitative adsorption predictions and demonstrate the power of MLIP-MC to rapidly test models.
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All authors Connor W. Edwards, Fengxu Yang, Konstantin Stracke, Jack D. Evans
Mesoscale and Nanoscale Physics
Polar unidirectional magnetotransport in $p-$type tellurene from quantum geometry
Claudio Iacovelli, Pierpaolo Fontana, Victor Velasco et al. (+5 more)
Unidirectional magnetoresistance, or electric magnetochiral anisotropy (eMChA), is a nonlinear magnetotransport phenomenon that arises in noncentrosymmetric conductors , where changes in resistance $R(B)$ are: (i)
chiral, $\Delta R(B)/R(0)=2\,\chi\, {\bf I}\cdot{\bf B}$, or (ii) polar, $\Delta R(B)/R(0)=2\,\gamma\, {\bf I}\cdot({\bf P}\times{\bf B})$, with eMChA coefficients $\chi$ and $\gamma$. In [Phys. Rev. Lett. 135, 106602 (2025)], we showed that the eMChA in the conduction band of tellurene is polar ($\chi=0$, $\gamma\neq 0$) and emerges from the
quantum metric dipole due to its Weyl node and from the lone pair polarization ${\bf P}$. Here, we extend our work to the valence band of tellurene, where the eMChA is usually said to be
chiral ($\chi \neq 0, \gamma = 0$). We show that also a polar coefficient $\gamma \neq 0$ emerges naturally through a downfolding procedure, in which remote Weyl-node containing bands induce momentum-space gradients of the
quantum metric in the low-energy levels, activating finite metric dipoles. Combining semiclassical Boltzmann transport with a ${\bf k}\cdot{\bf p}$ description of tellurene, our numerical calculations agree quantitatively with doping ($\mu$) dependent second-harmonic measurements of the longitudinal voltage $V^{2\omega}_\parallel(\mu)$ in perpendicular field. The combined
chiral and polar characters ($\chi\neq0, \gamma\neq 0)$ of the eMChA in tellurene also explains the shift in the angular ($\phi$) dependence of $V^{2\omega}_\parallel(\phi)$ for in plane fields. Our results demonstrate that the polar eMChA can arise in topologically trivial bands through multiband effects and establishes tellurene as a platform for
quantum-
geometric rectification in both electron and hole regimes.
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All authors Claudio Iacovelli, Pierpaolo Fontana, Victor Velasco, Chang Niu, Peide D. Ye, Marcus V. O. Moutinho, Caio Lewenkopf, Marcello B. Silva Neto
Mesoscale and Nanoscale Physics
Quantitative models for excess carrier diffusion and recombination in STEM-EBIC experiments on semiconductor nanostructures
Tobias Meyer, Christoph Flathmann, David A. Ehrlich et al. (+4 more)
The increased complexity and reduced size of (opto-)electronic devices demands for quantitative descriptions of excess carrier transport and recombination via various mechanisms. In addition, experimental methods capable of resolving carrier dynamics on the nanometer scale are required. In this paper, we present a quantitative model of a confined geometry including recombination at two surfaces, which is very generic for electron beam induced current measurements in a scanning transmission electron microscope - a method which offers atomic scale spatial resolution. The model is based on analytical considerations as well as finite element simulations and underlying assumptions are subjected to an in-depth discussion. Finally, the successfull application to experimental data obtained on the complex
oxide SrTi0.995Nb0.005O3 demonstrates the practicality and robustness of the approach, which enables the precise determination of its bulk
diffusion length of L = 10.2 +- 0.1 nm.
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All authors Tobias Meyer, Christoph Flathmann, David A. Ehrlich, Patrick Paap-Peretzki, Jonas Lindner, Christian Jooß, Michael Seibt
Mesoscale and Nanoscale Physics
Disorder-Induced Topological Phases in a Two-Dimensional Chern Insulator with Strong Magnetic Disorder
Devesh Vaish and Michael Potthoff
Strong directional disorder in local
magnetic moments coupled to a Chern
insulator gives rise to topological phases that cannot be continuously connected to the clean limit and are therefore genuinely disorder-driven. We demonstrate this in a spinful Qi-Wu-Zhang model of a two-dimensional Chern
insulator coupled to disordered classical
spins of unit length. The topological phase diagram is computed numerically using two complementary approaches: twisted boundary conditions and the topological
Hamiltonian technique. Our results show that strong disorder can act as a fundamental topological mechanism rather than merely a perturbation. For strong exchange coupling, tuning the mass parameter reveals a transition between phases with different Chern numbers $C$. Remarkably, this transition is driven by zeros, rather than poles, of the disorder-averaged Green's function crossing the chemical potential, and has no analogue in any clean system. We further identify a strong-coupling phase with $C = 0$ that is nonetheless topologically nontrivial, characterized by a distinct Chern number $C^{(\mathrm{S})} \neq 0$ over the
manifold of classical
spin configurations. This phase is also disorder-driven, as $C^{(\mathrm{S})} = 0$ in the clean limit.
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Strongly Correlated Electrons
Localized-basis formulation of interacting Hamiltonians in flat topological bands: coherent states and coherent-like states for fractional physics
Nobuyuki Okuma
In topological bands, it is impossible to construct exponentially localized Wannier functions while preserving the
symmetries. Instead, in
quantum Hall systems, one can define an overcomplete basis of spatially localized coherent states. In this work, we propose a unified framework for understanding the
quantum Hall effect and Chern
insulators from the perspective of localized bases, by extending the overcomplete basis of coherent states to Chern bands in terms of coherent-like states. Specifically, by representing both coherent states and coherent-like states as wave packets defined on a band, the difference between them can be encoded solely in the functional form of the wave packet in momentum space. Furthermore, for filling factor $\nu=1/3$, we define a local repulsive interaction
Hamiltonian based on these bases and discuss properties of its ground states. In particular, by relating this
Hamiltonian to previously studied models, we show that in
quantum Hall systems it possesses exactly zero-energy ground states with topological degeneracy, thereby confirming that it serves as a model for fractional
quantum Hall systems. In addition, we numerically verify that the
Hamiltonian possesses topological degeneracy for representative Chern
insulator models. An advantage of this formulation is that it allows fractional
quantum Hall systems and various fractional Chern
insulator systems to be discussed within a unified framework using the same
Hamiltonian form. In addition, we discuss that coherent-like states can also be defined in $\mathbb{Z}_2$ topological
insulators. Corresponding to the fermionic time-reversal
symmetry of the system, Kramers-degenerate coherent-like states can be naturally defined. The localized basis constructed from coherent-like states is expected to be useful for describing strongly correlated topological phases in flat-band systems.
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Statistical Mechanics
Mesoscopic MCT theory resolves Giant Non-Gaussian Parameter and Flory's conjecture
Yikun Ren, Feixiang Xu and Ming Lin
Extending Prigogine's ideas to the interior of the system, we generalize mode-coupling theory from a microscopic to a mesoscopic formulation by incorporating the non-
equilibrium eigen-phase. The resulting framework resolves two long-standing puzzles in glass transition physics with an error less than 0.01 against experiments: (i) the
giant non-Gaussian parameter $\alpha_{2} \sim 1-10$ which exceeds standard MCT predictions (only 0.1) by two orders of magnitude; (ii) the universal WLF constant $C_{1}=17 \ln 10 /(3 \sqrt{42}-19) \approx 16.7$, empirically observed for seven decades but never derived from first principles(e.g. Adam-Gibbs $C_{1}=8.5$, while other theories are off by more than a factor of two). These results establish mesoscopic MCT as a measurable foundation for non-
equilibrium thermodynamics, unifying dynamic heterogeneity and thermodynamic universality in glass-forming systems.
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Materials Science · Cross-listed from physics.optics
Surface defects in carbon-doped hexagonal boron nitride for negative-contrast direct laser writing
Dmitrii Litvinov, Virgil Gavriliuc, Magdalena Grzeszczyk et al. (+5 more)
Radiative defects in hexagonal boron nitride (hBN) are active in a broad spectral range from deep ultraviolet to near-infrared wavelengths. Representatives of these defects act as bright single
photon sources,
spin-1 systems, and multiproperty atomic-scale sensors. They are predominantly investigated in bulk hBN films, where defects are decoupled from surface and interfacial effects. Here, we demonstrate a novel class of surface defects optically active in the green/yellow visible spectral range, which exhibit photophysical properties distinct from their bulk counterparts. High-power resonant
laser illumination quenched the emission from the ensemble of such defects, which was attributed to a light-driven structural reconfiguration. The quenched defects were found to recover their emissive capabilities via a thermal cycling process, revealing an activation energy of 24.5 meV for the structural transition. Alternatively, permanent quenching of the defects was triggered by surface chemistry, involving lithiation-enabled attachment of functional groups. These mechanisms were utilized to realize negative-contrast direct
laser writing, designing arbitrary
geometric emissive patterns on demand in a microscopic configuration. The surface-active radiative centers in hBN appear particularly attractive for exploring environmental sensitivity, surface science, and coupling to photonic structures or electronic devices by taking unique advantage of the two-dimensional characteristics of the host
lattice.
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All authors Dmitrii Litvinov, Virgil Gavriliuc, Magdalena Grzeszczyk, Kristina Vaklinova, Kenji Watanabe, Takashi Taniguchi, Kostya S. Novoselov, Maciej Koperski
Strongly Correlated Electrons
Evolution of magnetic correlation in doped Hubbard model with altermagnetic spin splitting
Yinlong Li, Rana Imran Mushtaq, Ji Liu et al. (+4 more)
The
evolution of
magnetic correlation in strongly correlated electron systems with altermagentic
spin splitting remains largely unexplored. Here we investigate how
spin splitting generated by
spin-dependent next-nearest-neighbor hopping t' reshapes the
Fermi surface nesting and van Hove singularities in the two-dimensional square-
lattice Hubbard model, leading
evolution of
magnetic instabilities. Using the constrained-path
quantum Monte Carlo method, we find the dominant
magnetic correlation as functions of the filling and t'/t by computing the momentum-resolved
spin structure factor. The analysis reveals a transition from
antiferromagnetic ({\pi},{\pi}) order in the isotropic, half-filled system to non-collinear spiral ({\pi},q) order upon increasing the
spin-dependent anisotropy or doping away from half-filling, ultimately entering a short-range correlation regime where stripe and spiral correlation coexist. These findings highlight a possible route to realizing spiral correlation in altermagnetic systems, potentially providing a platform for spintronic devices that exploit non-collinear
spin textures.
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All authors Yinlong Li, Rana Imran Mushtaq, Ji Liu, Wing Chi Yu, Xiaosen Yang, Cho-Tung Yip, Ho-Kin Tang
Quantum Gases · Cross-listed from quant-ph
Ward-Takahashi Identity and Gauge-Invariant Response Theory for Open Quantum Systems
Hongchao Li, Xie-Hang Yu, Masaya Nakagawa et al. (+1 more)
We derive the Ward-Takahashi identity and establish the gauge-invariant response theory for open
quantum systems described by Lindbladians to show that particle-number conservation is not necessary to satisfy gauge invariance. We construct an observable which can be used to test the gauge invariance in the absence of particle-number conservation. We derive the low-energy collective modes that emerge as a consequence of gauge invariance in open
quantum systems, and find that two-body loss induces diffusive modes in dissipative Bardeen-Cooper-Schrieffer (BCS) superconductivity. Possible experimental situations for testing gauge invariance in open
quantum systems are also discussed.
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All authors Hongchao Li, Xie-Hang Yu, Masaya Nakagawa, Masahito Ueda
Mesoscale and Nanoscale Physics
Ballistic transport in nanodevices based on single-crystalline Cu thin film
Yongjin Cho, Su Jae Kim, Min-Hyoung Jung et al. (+7 more)
In ballistic transport, the movement of charged carriers is essentially unimpeded by scattering events. In this limit, microscopic parameters such as
crystal momentum,
spin and
quantum phases are well conserved, allowing electrons to maintain their
quantum coherence over longer distances. Nanoscale materials, like carbon nanotubes,
graphene, and nanowires, exhibit ballistic transport. However, their scalability in devices is significantly limited. While deposited metal films offer excellent scalability for nanodevices, achieving ballistic transport in these films poses a challenge due to their short electronic mean free path. Here, we investigated the electronic transport in cross-geometry devices fabricated with 90 nm-thick copper films without grain boundaries. We observed ballistic transport in devices with channel width smaller than 150 nm below 85 K by measuring negative bend resistance. Our findings would open the opportunity for probing intrinsic
quantum properties of Cu, and for realizing scalable low-loss signal transmission and high-quality interconnects in
semiconductor devices.
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All authors Yongjin Cho, Su Jae Kim, Min-Hyoung Jung, Yousil Lee, Hu Young Jeong, Young-Min Kim, Hu-Jong Lee, Seong-Gon Kim, Se-Young Jeong, Gil-Ho Lee
Materials Science
Anisotropic Core-Shell Swift Heavy Ion Tracks in beta-Ga2O3
Huan He, Jiayu Liang, Shaowei He et al. (+8 more)
Swift heavy ion (SHI) irradiation generates nanoscale ion tracks through intense electronic excitation, yet the microscopic mechanisms governing their morphology and phase stability in low
symmetry oxides remain poorly understood. Here, a multiscale atomistic simulation framework is used to investigate the formation and recovery of SHI-induced tracks in monoclinic $\beta$-Ga2O3 over a wide range of electronic energy losses (Se) and crystallographic orientations. A sequence of distinct structural responses is identified with increasing Se: (i) complete
lattice recovery at low Se; (ii) recrystallization into a metastable $\gamma$-Ga2O3 phase at intermediate Se; and (iii) the formation of core-shell ion tracks at high Se, consisting of an amorphous core surrounded by a recrystallized $\gamma$-phase shell. Despite the essentially isotropic initial energy deposition, the final ion-track morphology exhibits pronounced crystallographic anisotropy, governed by orientation-dependent recovery dynamics. The superior recrystallization along the [010] direction is attributed to its exceptionally high elastic stiffness. Notably, SHI irradiation perpendicular to the (100) plane induces a more severe structural response at low Se ($\le$ 10 keV/nm), however, at higher Se, it yields a smaller residual ion track compared to the other orientations. The simulated ion-track sizes show excellent quantitative agreement with the available experimental measurements over a wide range of Se values. These findings establish a unified atomic-scale picture of core-shell track formation and anisotropic recovery in $\beta$-Ga2O3.
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All authors Huan He, Jiayu Liang, Shaowei He, Yanwen Zhang, Jiahui Zhang, Ziqi Cai, Tan Shi, Hang Zang, Flyura Djurabekova, Chaohui He, Junlei Zhao
Mesoscale and Nanoscale Physics
Magnonic spontaneous oscillation induced by parametric pumping
Yi Li, Carissa Kiehl, Jinho Lim et al. (+10 more)
Spontaneous dynamic systems have attracted significant
attention for their rich underlying physics such as phase-locking and synchronization. In this work, we report a new mechanism of generating
magnetic spontaneous oscillation via parametric pumping. By applying a pump tone to excite propagating
spin waves in a yttrium iron garnet delay line, four-wave mixing converts the pump mode into two phase-autonomous propagating
magnon modes, i.e. a spontaneous mode with nearly twice the wavenumber of the pump mode and an idler mode with nearly zero wavenumber. This allows us to reliably generate ultrasharp
spin wave dynamics with broad frequency tunability from the pump and
magnetic field. We show that the spontaneous mode can be phase-locked to a probe tone, similar to an auto-oscillator. Furthermore, the spontaneous dynamics can be used to implement a high-gain magnonic parametric amplifier with a gain up to 40 dB. Our results open a new avenue for studying nonlinear magnonics and synchronization physics in propagating
magnon geometry and for developing new magnonic devices.
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All authors Yi Li, Carissa Kiehl, Jinho Lim, Cliff Abbott, Pratap K. Pal, Alex J. Szymczak, Juliang Li, Ralu Divan, Clarence L. Chang, Charudatta Phatak, Dmytro A. Bozhko, Axel Hoffmann, Valentine Novosad
Mesoscale and Nanoscale Physics
Electronic Structure of Multilayer Graphene with Arbitrary Stackings
Fred Sun and Jia-An Yan
Stacking geometry in multilayer
graphene (MLG) provides an interesting degree of freedom to engineer its electronic structure near the
Fermi level, wherein the linear bands in single layer
graphene could retain or evolve into
parabolic or flat bands. Using a tight-binding model, we carried out a detailed analytical analysis of the electronic band structures for arbitrarily stacked MLGs. We show that their low energy band dispersions near the
Fermi level may be deduced from its substacks in isolation. The analytical solutions of the momenta with zero
eigenvalue for an AA stacking allows us to generalize the results of the zero energy momenta for arbitrarily stacked MLGs. Moreover, we find that an interplay of parallel and rhombohedral stackings allows for flat band engineering and enhancement in arbitrarily stacked MLGs. The existence of flat bands in MLGs might offer another interesting platform for exploring the superconductivity in
graphene systems beyond the twisted
bilayer graphene.
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Mesoscale and Nanoscale Physics
Josephson-like magnetic tunnel junction – transition from classical to quantum regime
V.V.Yurlov, P.N. Skirdkov, K.A. Zvezdin et al. (+1 more)
We theoretically propose and analyze a Josephson-like
magnetic tunnel junction (MTJ) structure that exhibits
quantum spin dynamics analogous to those in superconducting Josephson junctions. By exploiting the isomorphism between the equations of motion for low-dissipation MTJs with easy-plane anisotropy and the Josephson phase dynamics, we construct a theoretical framework for realizing spintronic
qubits. Within this framework, we identify the physical parameters – such as anisotropy constants, Gilbert damping,
spin current amplitude, and
geometric factors – that govern the transition from classical to
quantum behavior. We show that different types of spintronic
qubits, including analogs of charge, flux, and transmon superconducting
qubits, can be implemented depending on the hierarchy of energy scales. A
Hamiltonian formalism is developed for each regime, enabling an analytical treatment of the two-level
quantum dynamics and estimation of coherence times. In particular, we demonstrate that the
spin current can be used not only to excite but also to stabilize the
qubit states through dissipation control. These findings provide a route toward integrating spintronic
qubits into CMOS-compatible architectures and lay the groundwork for a fully spintronic platform for
quantum computation.
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All authors V.V.Yurlov, P.N. Skirdkov, K.A. Zvezdin, A.K. Zvezdin
Materials Science
Altermagnetism, ARPES, symmetry, non-relativistic band splitting
Jiayu Liu, Xun Ma, Xinnuo Zhang et al. (+3 more)
Altermagnetism arises from composite real-space and
spin-space
symmetries, combining zero net magnetization with pronounced momentum-dependent
spin splitting. This review highlights the pivotal role of angle-resolved photoemission spectroscopy (ARPES), along with its
spin-resolved (SARPES) and circular-dichroism (CD-ARPES) variants, in directly visualizing nonrelativistic band splitting and
spin textures in altermagnets. Within the
spin-group framework, we distinguish
ferromagnetic,
antiferromagnetic, and altermagnetic orders and elucidate the
symmetry origin of
spin polarization. We then systematically review representative systems: the debated d-wave prototype RuO2, layered d-wave altermagnets KV2Se2O and Rb1-delta V2Te2O, and a series of g-wave compounds including MnTe (domain-tunable) and CrSb (topological), together with the noncoplanar antiferromagnet MnTe2 and other emerging candidate platforms. Overall, ARPES has become a key probe for resolving
symmetry-driven
spin splitting. Future advances in micro/nano-beam and in-situ spectroscopies, combined with strain and domain engineering,
heterostructure design, and exploration of broader unconventional
magnetic states, are expected to drive the joint
evolution of altermagnetism and photoemission spectroscopy, paving the way for spintronic and correlated
quantum research.
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All authors Jiayu Liu, Xun Ma, Xinnuo Zhang, Wenchuan Jing, Zhengtai Liu, Dawei Shen
Superconductivity
Metal hydrides achieve high-Tc superconductivity at low pressure by mimicking high-pressure H3S chemical bonding
Wendi Zhao, Shumin Guo, Chengda Li et al. (+4 more)
Compressed hydrides are promising candidates for high-temperature superconductivity, yet achieving simultaneous structural stability and high-Tc at low pressures remains challenging. Here, we introduce a new mechanism for accomplishing this goal by mimicking the bonding characteristics of high-pressure H3S within metal hydrides. Using Li3CuH4 as an example, its Cu-H covalent interaction effectively mimics the core function of the S-H bonding in H3S. This interaction not only induces a high hydrogen-derived electronic density of states at the
Fermi level, but also softens the hydrogen
phonon modes, thereby significantly enhancing the electron-
phonon coupling. Furthermore,
embedding the strongly ionic Li3H
lattice into the covalent Cu-H framework stabilizes the structure at significantly low pressures via a chemical-template effect, while maintaining high-Tc. Li3CuH4 exhibits excellent thermodynamic stability at 20 GPa, with a Tc of 39.25 K at 12 GPa. Further comprehensive high-throughput studies on Li3MH4 (M = transition metal) compounds uncover general principles applicable to a broader range of compounds. This work establishes a new paradigm for the simultaneous optimization of the stability and high-temperature superconductivity of metal hydrides through complementary sublattice interactions, thus advancing the search for practical and viable superconducting materials.
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All authors Wendi Zhao, Shumin Guo, Chengda Li, Abhiyan Pandit, Tian Cui, Defang Duan, Maosheng Miao
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Time-Domain Two-Magnon Interference Enabled by a Tunable Beamsplitter
Cody Trevillian, Steven Louis and Vasyl Tyberkevych
This letter presents a model system for controllable two-
magnon interference in the time domain. This two-
magnon interference, i.e., a magnonic analog to the photonic Hong-Ou-Mandel effect, is supported by a tunable magnonic beamsplitter operation formed in a hybrid cavity magnonic system comprising a pair of mutually coupled
magnon modes. By applying a time-dependent
magnetic field,
magnons can be excited independently in each mode and subsequently brought into interaction, shifting from independent to collective oscillations, to realize a controllable magnonic beamsplitter. When the beamsplitter operation is applied to an initially unentangled two-
magnon state, a maximally entangled magnonic $N00N$ state with tunable phase sensitivity is produced. These findings suggest that two-
magnon interference in hybrid cavity magnonic systems may enable novel
quantum metrological devices to study fundamental
magnon dynamics and contribute to developing hybrid magnonic
quantum computing architectures.
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