Materials Science
Double-pulse control of all optical magnetization reversal in Tb/Co multilayers
Sheng Li, Dinar Khusyainov, Rein Liefferink et al. (+7 more)
Recent experiments have shown that femtosecond
laser pulse with a Gaussian intensity profile can induce magnetization reversal in Tb/Co multilayers with a ring-shaped switching pattern within the
laser-irradiated area. Here, we investigate the ultrafast magnetization dynamics leading to such a ring-shaped switching by using double-pulse
laser excitation. The
laser pulses cause heat-induced quenching and subsequent recovery of the
magnetic anisotropy in the multilayers and drive the precessional magnetization switching in the
magnetic multilayers. By adjusting the delay between the two pump pulses, we demonstrate that the recovery process can be manipulated and show, experimentally and numerically, that this allows control over the final
magnetic domain pattern.
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All authors Sheng Li, Dinar Khusyainov, Rein Liefferink, Lukas Körber, Quoc-Trung Trinh, Ricardo C. Sousa, Liliana D. Buda-Prejbeanu, Johan H. Mentink, Theo Rasing, Alexey V. Kimel
Superconductivity
Quench of chiral superconductivity by quantum phase fluctuations in twisted cuprate bilayers
Yin Shi, Mengxian Zhao, Fei Yang et al. (+2 more)
Following theoretical proposals of
chiral $d+id'$ superconductivity in twisted cuprate
bilayers, experimental signatures of time-reversal
symmetry breaking (TRSB) remain highly controversial. Here we demonstrate that
quantum phase fluctuations fundamentally reshape the phase diagram of this proposed
chiral state. Unlike regular superconducting orders, the
chiral $d+id'$ state requires long-range coherence of an interlayer phase degree of freedom and is therefore intrinsically vulnerable to phase fluctuations. Incorporating these fluctuations nearly eliminates the
chiral phase over most parts of the phase diagram, restricting it to a narrow twist-angle window and ultra-low temperatures. Phase fluctuations also strongly weaken Josephson phase locking near a twist angle of $45^\circ$. More broadly, our work establishes
quantum phase fluctuations as a fundamental constraint on the emergence of TRSB phases in low-dimensional layered
quantum materials.
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All authors Yin Shi, Mengxian Zhao, Fei Yang, Miao Liu, Sheng Meng
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Evanescent absorption spectroscopy of transition metal dichalcogenide materials using guided photoluminescence in Si$_3$N$_4$ photonic waveguides
Victor Gonzalez-Morote, Marianna Sledzinska, Arkadiusz P. Gertych et al. (+3 more)
On-chip integration of two-dimensional transition metal dichalcogenides (TMDs) with photonic waveguides underpins a growing class of compact optoelectronic and sensing devices, whose performance depends on the optical absorption of the 2D material in this integrated environment. We demonstrate source-free, on-chip evanescent absorption spectroscopy of MoS$_2$ and WS$_2$ flakes integrated on Si$_3$N$_4$ waveguides, in which the broadband defect-related photoluminescence of the Si$_3$N$_4$ core itself acts as the internal probe. Light generated inside the core propagates under the TMD flake and is spectrally attenuated by evanescent interaction with the 2D material, and normalizing the transmitted spectrum to a reference waveguide without TMD yields the energy-dependent absorption response without any external illumination. The extracted guided absorption agrees with Raman and local micro-photoluminescence characterization and resolves differences between spatially uniform and non-uniform flakes. A complementary top-pumping scheme recovers guided WS$_2$ photoluminescence, whose spectral reshaping during propagation is quantitatively reproduced by the measured absorption. This source-free platform qualifies 2D materials in their integrated photonic environment and provides a direct route toward waveguide-integrated TMD photodetectors and sensors.
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All authors Victor Gonzalez-Morote, Marianna Sledzinska, Arkadiusz P. Gertych, Syed Hassan Abbas Jaffery, Mariusz Zdrojek, Daniel Navarro-Urrios
Materials Science
In vacuo synthesis of single-layer Ni3(HITP)2 on HOPG surface using metallo-organic precursor
Chuyu Song, Yifei Feng, Henan Chen et al. (+1 more)
Single-layer conjugated metal-organic frameworks (SL c-MOFs) are predicated theoretically to host rich
quantum phases. To date, however, the experimental synthesis has largely resulted in SL c-MOFs on metal substrates, whose intrinsic properties are strongly screened due to substrate hybridization. To overcome this obstacle, here we develop a method to grow clean SL c-MOF Ni3(HITP)2 on a chemically inert substrate of highly oriented pyrolytic graphite (HOPG). By means of an ultra-high
vacuum based multi-step protocol using nickel acetylacetonate [Ni(acac)2] precursor, we obtain continuous single-layer Ni3(HITP)2. Scanning tunneling microscopy reveals a well-defined hexagonal framework with a uniform azimuthal orientation rotated by approximately 30 degrees with respect to the underlying graphite
lattice. Furthermore, we control the growth of
bilayer Ni3(HITP)2 which features an unusual AA stacking configuration. This work establishes metallo-organic chemistry as an efficient route for integrating 2D c-MOFs onto inert substrates, which opens a new avenue for exploring the exotic
quantum properties of SL c-MOFs.
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All authors Chuyu Song, Yifei Feng, Henan Chen, Nian Lin
Mesoscale and Nanoscale Physics
Robustness of Quantum Discord in Nonequilibrium Electronic Transport through Tunnel-Coupled Quantum Dots
Thingujam Yaiphalemba Meitei, Saikumar Krithivasan, Md. Manirul Ali et al. (+1 more)
Quantum discord captures
quantum correlations beyond
entanglement and can remain finite even when the
entanglement vanishes. We investigate the transient nonequilibrium dynamics and steady-state behavior of
quantum discord and classical correlations in a double
quantum dot (DQD) system coupled to fermionic reservoirs. By employing a
quantum Langevin equation formalism, we obtain the exact reduced density
matrix of the system, enabling a comprehensive analysis of its
quantum and classical correlations under nonequilibrium conditions. The influence of system-reservoir coupling strength, spectral bandwidth, thermal bias, and varying initial state on both the transient dynamics and steady-state correlations is systematically analyzed.
Quantum discord remains finite in the nonequilibrium steady state over a broad parameter range. Although thermal gradients reduce the overall magnitude of correlations,
quantum discord persists and exhibits greater resilience. These results demonstrate that nonequilibrium electronic transport, together with the environmental spectral properties and reservoir asymmetry, provides an effective means of controlling nonclassical correlations in mesoscopic systems and establishes
quantum discord as a robust hallmark of open fermionic
quantum devices.
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All authors Thingujam Yaiphalemba Meitei, Saikumar Krithivasan, Md. Manirul Ali, Arijit Sen
Materials Science
Entropy-Driven Structural Phase Transition in Nb$_3$Cl$_8$ via Density Functional Theory and an Effective Model
Chenjie Zhu, Shuai Zhang, Zhong Fang et al. (+3 more)
As a prototypical flat-band cluster Mott
insulator on an effective triangular
lattice, Nb$_3$Cl$_8$ is a potential candidate for hosting a
quantum spin liquid (QSL) state. Nevertheless, a first-order structural phase transition around 90K transforms the high-temperature paramagnetic $\alpha$ phase into the low-temperature nonmagnetic $\beta$ phase, suppressing the candidate QSL regime of the $\alpha$ phase. To clarify the microscopic origin of this transition, we combine first-principles calculations with an extended Hubbard model to construct a unified free-energy framework. This framework reveals that the transition is jointly driven by
phonon and
spin entropy: the $\alpha$ phase is stabilized by softer
phonons and larger paramagnetic
spin entropy, whereas the $\beta$ phase is favored by interlayer dimerization, which hardens the
phonons and quenches the
spin entropy through singlet formation. Furthermore, by evaluating the pressure-dependent generalized enthalpy, we provide a thermodynamic explanation for the suppression of the transition under c-axis uniaxial pressure, where stabilizing the $\alpha$ phase may allow the candidate QSL regime of the $\alpha$ phase to be explored at low temperatures.
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All authors Chenjie Zhu, Shuai Zhang, Zhong Fang, Zhijun Wang, Quansheng Wu, Hongming Weng
Materials Science
A general-purpose atomic cluster expansion interatomic potential for niobium
Aleksei Egorov, Ralf Drautz and Thomas Hammerschmidt
Niobium, a body-centered cubic transition metal, poses a challenge for interatomic potentials, which struggle to capture its properties, such as
phonons, high-pressure behavior, energy barriers to dislocation glide, and others. To tackle this challenge, we constructed a general-purpose atomic cluster expansion (ACE) potential for niobium. We trained our ACE on thousands of density functional theory (DFT) structures spanning a diversity of local environments. We validated it across a range of properties and compared it with existing empirical and machine learning (ML) potentials, including a novel universal ML potential. The resulting ACE balances accuracy, efficiency, and robustness, enabling large-scale exploration of niobium with near-DFT precision. Finally, our ACE held its own in a stringent test: a near-million-atom molecular dynamics simulation of fracture
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Strongly Correlated Electrons
Strongly frustrated 2D magnetism in a 3D hexagonal perovskite
Bocheng Yu, Otkur Omar, Songtai Lv et al. (+12 more)
Exotic
quantum phenomena are often found to occur in
spin systems that exhibit low-dimensional magnetism. By combining
nuclear magnetic resonance,
neutron scattering, and
muon-
spin spectroscopy ($\mu$SR) techniques, we report a rare instance of strongly frustrated two-dimensional (2D) magnetism in a three-dimensional (3D) hexagonal perovskite. Here, Ba$_2$La$_2$MnTe$_2$O$_{12}$, a triangular-
lattice magnet, is shown to undergo a
magnetic transition at $T_\mathrm{N} \approx$ 4.4 K, below which the manganese moments form a 120$^{\circ}$ AFM order within the $ab$-plane, while staying disordered along the $c$-axis. This exotic ground state, which exhibits ideal 2D magnetism, is highly consistent with the persistently strong
spin fluctuations and the large internal field distributions revealed by zero-field $\mu$SR. Further, the 2D magnetism also leads to a significant frustration, much larger than that of most known magnetically-ordered frustrated systems. Our work on Ba$_2$La$_2$MnTe$_2$O$_{12}$ not only challenges the interpretations of
magnetic order in other 3D hexagonal perovskites, but it also provides insight into how the dimensionality affects the exotic
magnetic states.
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All authors Bocheng Yu, Otkur Omar, Songtai Lv, Long Ma, Zhengcai Xia, Jing Meng, Yanran Yang, Jie Ma, Yang Xu, Qingfeng Zhan, Vladimir Yu. Pomjakushin, Haiyuan Zou, Shang Gao, Toni Shiroka, Tian Shang
Materials Science
Effect of granules anisotropy on "double quantum" magnetic resonance excitation in nanogranular composites
A.B. Drovosekov, M.Yu. Dmitrieva, A.V. Sitnikov et al. (+2 more)
Films of metal-
insulator nanogranular composites (CoFeB)x(Al2O3)100-x with different contents of the metal
ferromagnetic (FM) phase CoFeB (x ~ 15-50 at.%) are investigated by the method of electron
spin resonance (ESR) in a wide range of frequencies (f = 7-80 GHz) and temperatures (T = 4.2-300 K). Besides the conventional FM resonance signal, the experimental spectra demonstrate an additional absorption peak with a double effective g-factor g ~ 4 which is explained within the
quantum mechanical "
giant spin" model by excitation of "double
quantum" transitions in FM granules CoFeB. According to the theory, the intensity of this "double
quantum" peak is a complex function of frequency and temperature, including as parameters the granule
magnetic moment and anisotropy. Experimentally, the size and anisotropy of the granules can be varied either changing the nominal FM phase content x in the composites or annealing the samples at different temperatures. Here we study the effects of concentration x and thermal annealing of (CoFeB)x(Al2O3)100-x films on their ESR spectral parameters. The observed behavior of the "double
quantum" peak intensity is well explained within the considered "
giant spin" theoretical concept. In conclusion, we demonstrate the correlation between the size of FM granules in nanocomposites and their anisotropy, indicating the surface origin of this anisotropy.
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All authors A.B. Drovosekov, M.Yu. Dmitrieva, A.V. Sitnikov, S.N. Nikolaev, V.V. Rylkov
Mesoscale and Nanoscale Physics
Real-time dynamics of triplet-resonant tunneling driven by nonequilibrium phonons
Kazuyuki Kuroyama, Sasha R. Valentin, Arne Ludwig et al. (+4 more)
Driven nonequilibrium systems can host emergent functionalities beyond
equilibrium, but real-time access to excited-state dynamics remains limited. Here we report real-time measurements of
phonon-driven charge and
spin dynamics in excited states of a double
quantum dot. Under
phonon irradiation, resonant inter-dot tunneling emerges at triplet resonance. Time-resolved charge sensing reveals that the resonant inter-dot tunneling is strongly modified by
spin blockade. For weaker inter-dot coupling, the nonequilibrium
phonon environment generates a unidirectional transport cycle along the
phonon density gradient.
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All authors Kazuyuki Kuroyama, Sasha R. Valentin, Arne Ludwig, Andreas D. Wieck, Yasuhiro Tokura, Seigo Tarucha, Sadashige Matsuo
Materials Science
Atom-selective spin-polarized transport in a charge-ordered altermagnet
Liu Yang, Yuan-Yuan Jiang, Xiao-Yan Guo et al. (+6 more)
Altermagnets provide a promising platform for
spin-polarized transport without net magnetization, but their transport properties are usually discussed in terms of momentum-space
spin splitting. Here, using first-principles calculations and
quantum transport simulations, we show that the charge-ordered altermagnet $\alpha$-Fe$_2$PO$_5$ exhibits a distinct form of real-space
spin selectivity despite weak altermagnetic
spin splitting near the
Fermi level. The charge order creates inequivalent Fe$^{2+}$ and Fe$^{3+}$ sites within each sublattice, while the puckered C-type
antiferromagnetic stacking suppresses inter-sublattice transport. As a result, electron and hole doping activate
spin-polarized transport predominantly through Fe$^{3+}$- and Fe$^{2+}$-based channels, respectively. These atom-selective channels carry opposite
spin polarizations on the two
antiferromagnetic sublattices, giving rise to a globally compensated charge current with hidden Néel
spin character. We further propose an all-in-one $\alpha$-Fe$_2$PO$_5$ tunnel junction, where matching or mismatching atom-selective conduction channels yields orders-of-magnitude conductance modulation. Our findings establish a real-space design principle for atomically controlled
spin functionality and spintronic devices.
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All authors Liu Yang, Yuan-Yuan Jiang, Xiao-Yan Guo, Yi-Dong Liu, Xian-Zhe Chen, Wen-Jian Lu, Yu-Ping Sun, Ming Li, Ding-Fu Shao
Strongly Correlated Electrons
Weak Ferromagnetism in NiS$_2$ under Nanocrystallization
Hayato Miyazaki, Tomohiko Yoshinaga, Ojiro Miyazaki et al. (+7 more)
Structurally well-ordered NiS$_2$ nanocrystals with an average diameter of $27.0 \pm 6.5$ nm retain the bulk-like two-step
antiferromagnetic transitions, as shown by magnetization and heat-capacity measurements. Below the lower transition, the nanocrystals exhibit a hysteretic
ferromagnetic response with large coercivity, exchange bias, and a vertical loop shift after field cooling, whereas the $M$-$H$ response just above the transition is nearly linear. These features are best explained by uncompensated surface moments generated where the low-temperature
antiferromagnetic order terminates at the nanocrystal surface. The absence of a clear additional bulk-like weak-
ferromagnetic component constrains homogeneous-canting models and indirectly favors a domain-wall scenario for the weak ferromagnetism of bulk NiS$_2$.
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All authors Hayato Miyazaki, Tomohiko Yoshinaga, Ojiro Miyazaki, Akira Matsuo, Koichi Kindo, Hirofumi Ishii, Tatsuya Kawae, Tetsuya Kida, Masashi Nantoh, Yoichi Ishiwata
Statistical Mechanics
Single-cell-level distributions and relationships can differentiate cell-division and growth models
Vikas, Rahul Marathe and Anjan Roy
Complex interactions among regulatory molecules determine the rules underlying
cell growth and division in microbial
cells. While the governing molecular network may not always be obvious, it is well known that correlations among certain physiological quantities measured in experiments, such as birth-size, division-size, division-time, and division-added-size, can differentiate among various
cell-division models, such as Timer, Sizer, and Adder. Here we show that, apart from these correlations, which we extend for the case of
stochastic single-
cell growth and
stochastic asymmetric partitioning, probability distributions of these quantities and statistical relationships between them can also be used to differentiate between these division models. Interestingly, we show that these quantities can not only differentiate the division models, but also distinguish among the single-
cell growth paradigms, such as linear and exponential growth. We then demonstrate this differentiability among various division and growth models by comparing our analytical results with published experimental data. We further show that these results remain valid even when the growth rate of a
cell is correlated with the growth rate of
cells from previous generations in the lineage.
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Statistical Mechanics
Slow heat-driven flow in a gas of hard disks
Amit Kumar, Abhishek Dhar and Baruch Meerson
We study a slow heat-driven flow in a gas of elastically colliding hard disks confined to a long channel. The initial state consists of two regions with large temperature and density contrasts but nearly equal pressures, leading to a low-Mach-number, nearly isobaric
evolution. In the dilute limit, the corresponding isobaric hydrodynamic theory reduces to a previously known ideal-gas description. We extend this theory to finite densities by incorporating a non-ideal equation of state of a hard-disk fluid, and solve the resulting one-dimensional equations numerically. Finite-density effects produce appreciable deviations from the ideal-gas prediction. We then test the theory directly against event-driven molecular dynamics simulations of hard disks and find very good agreement in both the dilute and finite-density regimes. The results provide, to our knowledge, the first particle-level test of isobaric gas dynamics of a strongly inhomogeneous cooling flow.
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Superconductivity
Transforming Native Oxide into a Metallic Platinum–Niobium Alloy for Passivation of Superconducting Niobium Films
Ananya Chattaraj, Conan Weiland, Bruce Ravel et al. (+10 more)
Dielectric losses at surfaces and interfaces remains a primary limitation to coherence in superconducting transmon
qubits. Niobium (Nb), a widely used material in superconducting
quantum circuits, readily forms native
oxides under ambient conditions, leading to lossy dielectric interfaces that degrade device performance. Here, we demonstrate a novel fabrication strategy that chemically transforms the native dielectric
oxide on Nb into a metallic Pt–Nb surface
alloy through post-oxidation Pt deposition followed by thermal annealing, thereby stabilizing Nb surfaces against further oxidation, potentially including sidewall regions. High-purity Nb films were fabricated with bulk-like superconducting transition temperatures ($T_c = 9.30\pm0.10$~K). Spectroscopic and microscopic analyses confirm the conversion of the native
oxide into a chemically stable, metallic
alloy-dominated layer that suppresses subsequent
oxide growth. Ab initio simulations elucidate the atomic-scale rearrangement and electronic structure
evolution associated with Pt incorporation into native niobium
oxide, providing insight into the mechanism underlying the
oxide-to-metal transformation and stabilization of the alloyed surface.
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All authors Ananya Chattaraj, Conan Weiland, Bruce Ravel, Kim Kisslinger, Sooyeon Hwang, Xiao Tong, Ajith Pattammattel, Andrew M. Kiss, Steven L. Hulbert, Aswin kumar Anbalagan, Andrew L. Walter, Peter V. Sushko, Mingzhao Liu
Materials Science
Modulation of the Nernst Thermoelectrics by Regulating the Anomalous Hall and Nernst Angles
Meng Lyu, Junyan Liu, Jianlei Shen et al. (+8 more)
The large anomalous Nernst effect in
magnetic Weyl semimetals is one of the most intriguing transport phenomena, which draws significant
attention for its potential applications in topological thermoelectrics. Despite frequent reports of substantial anomalous Nernst conductivity (ANC), methods to optimize Nernst thermoelectrics remain limited. Our research reveals that the magnitude of the ANC is directly related to the sum of the anomalous Nernst and
Hall angles. While the sign of the anomalous
Hall angle is relatively stable in a certain material, the sign of the anomalous Nernst angle can be intrinsically tuned. Therefore, the ANC can be effectively optimized by regulating these angles to work in concert. This finding is verified by experimental modulation from iron-doped
magnetic topological material Co3Sn2S2. Additionally, we observed a robust TlnT scaling law of the ANC over the temperature range of 40 to 140 K in all studied samples, suggesting an intrinsic origin of the ANC. Considering the common opposite sign of the anomalous Nernst and
Hall angles in many
magnetic topological materials, our research offers an applicable scheme for optimizing the Nernst thermoelectrics.
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All authors Meng Lyu, Junyan Liu, Jianlei Shen, Shen Zhang, Yang Liu, Jinying Yang, Yibo Wang, Yiting Feng, Binbin Wang, Hongxiang Wei, Enke Liu
Soft Condensed Matter · Cross-listed from physics.bio-ph
A bilayer cellular Potts model of epithelial docking
Troy Singletary, Andrea James and Tyler A. Engstrom
Fusion of two epithelial
cell sheets brought together in a
bilayer configuration is a common step in animal morphogenesis, yet, in contrast to other epithelial fusion processes such as wound healing in a monolayer of
cells, it has not been a strong focus of modeling efforts. Here we consider a preliminary stage of
bilayer fusion, recently termed "docking." In multiple instances of docking that span apical and basal varieties,
cells appear to have a tendency to remodel so as to co-localize their bilateral junctions (match their edges) across the
bilayer. Motivated by this observation, we introduce a
bilayer cellular Potts model that couples two standard 2D area- and perimeter-elasticity models via short-range, out-of-plane interactions between
cell edges. The new coupling involves a single adjustable parameter that minimally models the combined effect of dynamic cytoskeletal protrusions, cadherins, and other potential edge-associated adhesion molecules. Our model predicts that
bilayer edge matching is maximized when the two monolayers are in their fluid-like regimes (average
cell shape index greater than 4.6 in our implementation), and when the
bilayer coupling strength strikes a balance between in-plane and out-of-plane energy scales. At higher coupling strengths, the system tends to get stuck in metastable states with sub-optimal edge matching. Exploration of the mechanisms of edge matching reveals that pairs and quadruplets of coordinated T1 transitions play a particularly important role. We also find numerous examples of emergent features we term "domain walls" - branching or unbranching curves that cross no matched edges, but that separate regions of nearly complete matching. These domain walls can be both system spanning and long lived. Finally, we extend our model to crudely account for bending of the two sheets, and study the distributions of docking front speeds that result.
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Strongly Correlated Electrons
Holographic Quantum Transformer: A Generalist Neuro-Symbolic Architecture for Solving Frustrated Systems via Generative Attention
Xingran Guo, Tiaojie Xiao, Jie Liu et al. (+1 more)
Simulating two-dimensional frustrated
quantum matter is a grand challenge due to the sign problem and exponential
Hilbert space complexity. In this work, we introduce the
Holographic Quantum Transformer (HQT), a physics-inspired generative architecture that leverages global self-
attention to resolve non-local
entanglement patterns. We validate HQT on the square
lattice $J_1-J_2$ Heisenberg model. On the heavily frustrated $8 \times 8$
lattice at the
quantum critical point ($J_2=0.5$), HQT reaches a ground-state energy per site ($E/N$) of $\mathbf{-0.5001(1)}$, consistent with the expected finite-size scaling trend. Beyond numerical accuracy, HQT exhibits intrinsic physical awareness, autonomously recovering the underlying $J_2$ interaction geometry through interpretable
attention maps. Our central contribution is “
Holographic Transfer", a zero-shot size-extrapolation protocol with rapid
alignment: a model trained on $8 \times 8$ systems is directly projected onto larger $10 \times 10$
lattices via continuous positional-
embedding interpolation and head re-initialization, achieving high-fidelity initialization and rapid convergence. This zero-shot protocol yields an energy of $E/N = \mathbf{-0.49782(3)}$, statistically consistent with the variational state of the art while requiring no from-scratch training on the target
lattice. Our results establish generative
attention as a scalable paradigm for transferable
quantum simulation.
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All authors Xingran Guo, Tiaojie Xiao, Jie Liu, Keqin Li
Mesoscale and Nanoscale Physics
Modulation of anomalous Hall angle in a magnetic topological semimetal
Jinying Yang, Yanxing Shang, Xingchen Liu et al. (+14 more)
The anomalous
Hall angle ({\theta}A) is a measure of the efficiency of converting a longitudinal driving current to a transverse
spin-polarized
Hall current. For anomalous
Hall sensing, a large anomalous
Hall angle can improve the sensitivity of
magnetic field detection. However, modulation of this angle is challenging and
magnetic materials typically have low angles of 0.1 to 3{\deg}. Here, we report modulation of the anomalous
Hall angle in the
magnetic Weyl semimetal Co3Sn2S2. We propose that the angle parameter tan{\theta}A can be formulated as a function of the product of electrical resistivity and anomalous
Hall conductivity. Our scheme was utilized to demonstrate the modulation of tan{\theta}A up to a magnitude of 0.46, corresponding to an angle of around 25{\deg}. Microfabricated anomalous
Hall devices using Fe-doped Co3Sn2S2 single-crystalline nanoflakes exhibit a high
Hall sensitivity of 7028 {\mu}{\Omega}ucm/T and a
magnetic field detectability of 23.5 nT/Hz0.5 at 1 Hz.
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All authors Jinying Yang, Yanxing Shang, Xingchen Liu, Yibo Wang, Xuebin Dong, Qingqi Zeng, Meng Lv, Shen Zhang, Yang Liu, Binbin Wang, Hongxiang Wei, Yizheng Wu, Stuart Parkin, Gangqin Liu, Claudia Felser, Enke Liu, Baogen Shen
Statistical Mechanics · Cross-listed from quant-ph
Subsystem Thermalization and Work Statistical Characterizations of Floquet Dynamics
Feng-Li Lin and Ching-Yu Huang
We study Floquet thermalization in a periodically driven
quantum non-integrable Ising chain by combining two operational diagnostics: subsystem thermalization and work statistics. For generic interacting Floquet systems, stroboscopic dynamics lead to heating toward an infinite-temperature state at low driving frequencies, to a prethermal state during the crossover regime, and then to a finite-temperature state at high driving frequencies. We show that reduced density
matrices of small subsystems provide a precise measure of local equilibration and clearly resolve prethermal plateaus. In parallel, we analyze the statistics of work performed over a Floquet cycle using both the characteristic function of work with and without the two-point measurements, and the related fluctuation
theorem, which captures coherent contributions and deviations from thermal
equilibrium. By comparing these two diagnostics within the same Floquet setting, we demonstrate that work statistics encode the same dynamical crossover that governs subsystem thermalization. Our results establish a unified and experimentally accessible framework for characterizing Floquet thermalization, prethermal regimes, and coherent energy absorption in interacting
quantum systems.
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Mesoscale and Nanoscale Physics
Universal Scaling of the Spin Hall Effect
Atsuo Shitade and Naoto Nagaosa
We study the
spin Hall (SH) effect for the Dirac electrons in terms of the
spin and
magnetic-moment accumulation coefficients $-\Gamma^{00} g_{s(m)z}^{\phantom{s(m)z} xy}$. We take short-range nonmagnetic
impurities into account within the self-consistent $T$-
matrix approximation. Similarly to the universal scaling for the anomalous
Hall (AH) effect, we find three disctinct regimes by changing the electric conductivity $\sigma^{yy}$; the superclean regime with $-\Gamma^{00} g_{s(m)z}^{\phantom{s(m)z} xy} \propto \sigma^{yy}$ owing to the skew scattering, moderately dirty regime with almost constant $-\Gamma^{00} g_{s(m)z}^{\phantom{s(m)z} xy}$, and dirty regime with a new scaling relation $-\Gamma^{00} g_{s(m)z}^{\phantom{s(m)z} xy} \propto (\sigma^{yy})^{0.6}$ whose exponent differs from that of the AH conductivity. Our results construct a unified theory of the SH effect without any ambiguity of
spin current.
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Statistical Mechanics · Cross-listed from quant-ph
Coupling effect of nearest-neighbor interacting qubit chains to a single qubit system
Manuel Allan L. Orongan, Lemuel John F. Sese and Rayda P. Gammag
This study establishes a
theorem that provides sufficient criteria for identifying terms in any time-independent
Hamiltonian that have no influence on local dynamics, local observables, or any local phenomena, without any approximation. The usefulness of this
theorem is demonstrated by predicting the behavior of three systems. The first system consists of multiple
qubit chains with Ising interactions. The second system is formed by a single
qubit chain, differentiated by the substitution of Dzyalonshinskii-Moriya (DM) interaction for the last Ising interaction. The predictions were verified by analytically deriving the reduced dynamics of both systems. A third system was also considered, namely, a short
qubit chain with a transverse
magnetic field on the intermediary environment
qubit. This transverse
magnetic field signals that the commutation relation required by our
theorem no longer holds. The third system's local dynamics were also derived analytically, demonstrating that all
Hamiltonian constituents contributed to the reduced dynamics. The physical consequences of our
theorem's inapplicability were also explored using this third system by analyzing the
entanglement dynamics between the
qubits that do not directly interact. The results showed that the
entanglement is caused by an emergent coupling between the two non-directly interacting subsystems. This emergent coupling arises from the non-commutativity of the intermediate interactions connecting the two subsystems. When searching for these emergent couplings, our
theorem can eliminate intermediate interactions that will not produce them.
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