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2606.03278 2026-06-03 cond-mat.mes-hall quant-ph

Tailoring pure valley-Zeeman spin-orbit coupling in WSe$_2$-encapsulated monolayer graphene

在WSe$_2$封装单层石墨烯中定制纯谷-塞曼自旋轨道耦合

Yaqing Han, Siqi Jiang, Jingkuan Xiao, Jiawei Jiang, Yulu Liu, Jiabei Huang, Yu Du, Di Zhang, Fuzhuo Lian, Wanting Xu, Siqin Wang, Kenji Watanabe, Takashi Taniguchi, Xiaoxiang Xi, Alexander S. Mayorov, Renjun Du, Kai Chang, Hongxin Yang, Lei Wang, Geliang Yu

AI总结 通过平行扭转WSe$_2$双层封装单层石墨烯,实现了纯谷-塞曼自旋轨道耦合,并观察到朗道能级的对称性重排及量子霍尔效应的四重简并恢复。

Comments accepted in Physical Review Letters

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AI中文摘要

在扭转范德华异质结构中工程化邻近效应为设计电子性质提供了强大平台。尽管过渡金属二硫族化物封装石墨烯中的量子干涉理论预测可选择性地控制自旋轨道耦合分量,但实验实现一直难以捉摸。在此,我们报告了在单层石墨烯中实现的纯谷-塞曼自旋轨道耦合,通过两个平行扭转的WSe$_2$单层封装实现。我们观察到由固定谷-塞曼能与磁场依赖的回旋能之间的竞争驱动的朗道能级的对称性强制重排。这种重排的特征是从量子霍尔效应中的对称破缺态转变为具有整数或半整数量子霍尔序列的恢复四重简并。我们还展示了通过调节封装几何结构来完全猝灭邻近自旋轨道耦合的能力。

英文摘要

Engineering proximity effects in twisted van der Waals heterostructures offers a powerful platform for designing electronic properties. While theoretical predictions of quantum interference in transition metal dichalcogenide-encapsulated graphene can selectively control the spin-orbit coupling component, experimental realizations have remained elusive. Here, we report pure valley-Zeeman spin-orbit coupling in monolayer graphene, achieved by encapsulation between two parallel twisted WSe$_2$ monolayers. We observed a symmetry-enforced reordering of Landau levels, which is driven by the competition between the fixed valley-Zeeman energy and the magnetic-field-dependent cyclotron energy. This reordering is characterized by a transition from symmetry-broken states in the quantum Hall effect to a restored fourfold degeneracy with integer or half-integer quantum Hall sequences. We also demonstrate the ability to completely quench the proximity spin-orbit coupling by tuning the encapsulated geometry.

2606.03235 2026-06-03 cond-mat.soft

Monte-Carlo study of Compositional Heterogeneity in Multicomponent Cluster Crystals

多组分团簇晶体中成分异质性的蒙特卡洛研究

Roshan Maharana, Daan Frenkel, Jure Dobnikar

AI总结 通过蒙特卡洛模拟和密度泛函理论,研究二元团簇晶体中由密度驱动的从均匀混合态到异质“合金”状固体的转变,揭示其由团簇与去混合不稳定性竞争控制,并导出定量标度律。

Comments 7 pages, 4 figures

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AI中文摘要

具有有界相互作用的软(亚)微米级颗粒可以形成团簇晶体,即多个颗粒占据同一格点的周期结构。虽然单分散团簇晶体的热力学已得到充分理解,但成分无序如何影响其稳定性尚不清楚。利用蒙特卡洛模拟和密度泛函理论,我们展示了二元团簇晶体经历一个由密度驱动的转变,从均匀混合态转变为异质“合金”状固体,其中格点自发分化为具有不同成分和占据数的群体,同时保持底层晶体对称性。该转变伴随着平衡格点密度的急剧增加和成分涨落的增强,但我们没有观察到宏观相分离的证据。我们证明这一转变由团簇不稳定性和去混合不稳定性之间的竞争控制,并导出了去混合密度作为温度、成分和颗粒尺寸失配函数的简单标度律,与模拟结果定量一致。

英文摘要

Soft (sub)micron-sized particles with bounded interactions can form cluster crystals, periodic structures in which multiple particles occupy the same lattice site. While the thermodynamics of monodisperse cluster crystals is well understood, less is known about how compositional disorder affects their stability. Using Monte Carlo simulations and density functional theory we show that binary cluster crystals undergo a density driven transition from a homogeneous mixed state to a heterogeneous ``alloy" like solid in which lattice sites spontaneously differentiate into populations with distinct compositions and occupancies while preserving the underlying crystal symmetry. The transition is accompanied by a sharp increase in the equilibrium lattice site density and by increased compositional fluctuations, but we see no evidence for macroscopic phase separation. We demonstrate that this transition is governed by competition between clustering and demixing instabilities and derive a simple scaling law for the demixing density as a function of temperature, composition, and particle size mismatch, in quantitative agreement with simulation.

2606.03193 2026-06-03 cond-mat.mes-hall cond-mat.supr-con

Generation and time evolution of anomalous Floquet Majorana flat edge modes in two-dimensional noncolinear magnet-superconductor heterostructures

二维非共线磁体-超导体异质结构中反常Floquet马约拉纳平边缘模的产生与时间演化

Kamalesh Bera, Priyanka Mohan, Arijit Saha

AI总结 本文通过理论计算,在化学势谐波驱动的二维磁体-超导体异质结构中实现了无隙Floquet拓扑超导相,发现了常规0模和反常π模Floquet马约拉纳平边缘模,并利用卷绕数进行了拓扑表征。

Comments 12 Pages, 6 PDF Figures, Comments are welcome

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AI中文摘要

我们理论研究了在化学势中实现谐波驱动的二维磁体-超导体异质结构(2D Shiba晶格)中无隙Floquet拓扑超导相的实现。采用实空间紧束缚模型,我们在准能谱中获得了常规的$0$-和反常的$\pi$-Floquet马约拉纳平边缘模(FMFEMs)。我们还研究了FMFEMs的实时演化,并分析了它们在周期性驱动下的局域态密度。利用等效体有效动量空间哈密顿量的手征对称性,通过卷绕数进行了拓扑表征,这得到了相应边缘态谱的支持。此外,我们采用Brillouin-Wigner(BW)和Floquet微扰理论(FPT)来获得问题的解析洞察。我们比较了在不同频率范围内获得的准能谱的精确(数值)、BW和FPT结果。我们发现,在较高频率和高振幅区域,特别是接近$0$-准能量模时,精确数值、BW和FPT结果之间具有良好的一致性。

英文摘要

We theoretically investigate the realization of gapless Floquet topological superconducting phases in a two-dimensional magnet-superconductor heterostructure (2D Shiba lattice) in the presence of a harmonic drive implemented in the chemical potential. Employing a real-space tight-binding model, we obtain both the regular $0$- and anomalous $π$-Floquet Majorana flat edge modes (FMFEMs) in the quasi-energy spectrum. We also study the real-time evolution of the FMFEMs and analyze their local density of states in the presence of such a periodic drive. The topological characterization is performed using the winding number, exploiting the chiral symmetry of the equivalent bulk effective momentum-space Hamiltonian. This is also supported by the corresponding edge state spectra. Furthermore, we employ the Brillouin-Wigner (BW) and Floquet perturbation theory (FPT) to gain analytical insight into the problem. We compare our exact (numerical), BW, and FPT results in terms of the quasi-energy spectra obtained across different frequency regimes. We find good agreement between the exact numerical, BW, and FPT results in the higher-frequency and high-amplitude domain, particularly close to the $0$-quasi-energy modes.

2606.03124 2026-06-03 cond-mat.str-el

Many-Body Non-Hermitian Physics in the Generalized Brillouin Zone

广义布里渊区中的多体非厄米物理

Chaoze Lu, Chuanshu Xu, Zhenghao Yang, Xiancong Lu

AI总结 通过广义布里渊区变换构造准互易多体哈密顿量,利用精确对角化研究其相图,发现纠缠谱简并性表征各相,揭示了非厄米多体系统的拓扑性质。

Comments 5 pages, 4 figures

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AI中文摘要

非厄米系统中传统体边对应关系的失效可以通过广义布里渊区理论解决。然而,将广义布里渊区理论推广到相互作用多体系统仍然是一个开放问题。本文考虑一个以圆形广义布里渊区为特征的相互作用非厄米模型。我们证明,基于广义布里渊区变换,可以构造一个准互易多体哈密顿量,该哈密顿量在周期性边界条件下捕捉了原始非厄米模型在开放边界条件下的物理。利用精确对角化,我们通过计算Zak相位和电荷密度波相的结构因子,确定了准互易多体哈密顿量的相图。我们进一步研究了纠缠性质,发现低能纠缠谱的简并性表征了相图中的每个相。这些发现表明,相互作用非厄米系统中的拓扑性质编码在准互易模型的纠缠谱中。我们的工作建立了一条在广义布里渊区框架内研究多体非厄米物理的途径。

英文摘要

The breakdown of conventional bulk-boundary correspondence (BBC) in non-Hermitian system can be resolved by the generalized Brillouin zone (GBZ) theory. However, extending the GBZ theory to interacting many-body systems remains an open problem. Here, we consider an interacting non-Hermitian model characterized by a circular GBZ. We show that, based on a GBZ transformation, a quasi-reciprocal many-body Hamiltonian can be constructed which, under periodic boundary conditions (PBC), captures the physics of the original non-Hermitian model under open boundary conditions (OBC). Using exact diagonalization (ED), we determine the phase diagram for the quasi-reciprocal many-body Hamiltonian by computing the Zak phase and the structure factor of the charge-density-wave (CDW) phase. We further investigate the entanglement properties and find that the degeneracy of the low-lying entanglement spectrum characterizes each phase in the phase diagram. These findings demonstrate that the topological properties in interacting non-Hermitian system is encoded in the entanglement spectrum of the quasi-reciprocal model. Our work establishes a route to studying many-body non-Hermitian physics within the GBZ formalism.

2606.03060 2026-06-03 cond-mat.mtrl-sci

High-Throughput Discovery of Semimetallic Borophenes with Diverse Dirac States Via Transferable Tight-Binding Approach

通过可转移紧束缚方法高通量发现具有多种狄拉克态的半金属硼烯

Yuke Song, Shifang Li, Tao Ouyang, Chao Tang, Jin Li, Chaoyu He

AI总结 开发可转移紧束缚框架结合图论和群论随机生成策略,高通量筛选522种硼烯同素异形体,发现8种新型半金属硼烯,包含I型、III型狄拉克锥、狄拉克节线及首次预测的二次节点半金属。

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AI中文摘要

硼烯因其结构灵活性和涌现的拓扑电子态而受到广泛关注。然而,在大量预测的同素异形体中,具有稳健狄拉克态的半金属硼烯仍然罕见。在这里,我们为平面硼烯开发了一个可转移的紧束缚框架,并将其与基于图论和群论的随机生成策略相结合,对522种硼烯候选物进行高通量筛选。识别出八种先前未报道的半金属硼烯,它们具有多种拓扑能带交叉,包括I型和III型狄拉克锥、狄拉克节线和二次节点。值得注意的是,硼烯中首次预测了二次节点半金属。对称性分析揭示了晶体对称性保护的狄拉克态,而第一性原理计算证实了它们的动力学和热稳定性。这些发现确立了硼烯作为在二维中工程化涌现狄拉克物理的多功能平台。

英文摘要

Borophene has attracted extensive interest due to its structural flexibility and emergent topological electronic states. However, semimetallic borophenes hosting robust Dirac states remain rare among the large number of predicted allotropes. Here, we develop a transferable tight-binding framework for planar borophenes and combine it with a graph- and group-theory-based random generation strategy to perform high-throughput screening of 522 borophene candidates. Eight previously unreported semimetallic borophenes are identified, hosting diverse topological band crossings, including type-I and type-III Dirac cones, Dirac nodal lines, and quadratic nodal points. Notably, quadratic nodal-point semimetals are predicted in borophene for the first time. Symmetry analysis reveals crystalline-symmetry-protected Dirac states, while first-principles calculations confirm their dynamical and thermal stability. These findings establish borophene as a versatile platform for engineering emergent Dirac physics in two dimensions.

2606.03044 2026-06-03 cond-mat.quant-gas cond-mat.mes-hall nlin.PS

Observation of interaction-induced fast Thouless pumping of solitons

相互作用诱导的孤子快速Thouless泵浦的观测

Yuqing Li, Jinxiong Jia, Yunfei Wang, Huiying Du, Zhong An, Zhenhua Qiao, Liantuan Xiao, Suotang Jia, Qian Niu, Jie Ma

AI总结 通过实验研究原子玻色-爱因斯坦凝聚体中周期性调制晶格上的Thouless泵浦,发现中等相互作用下物质波孤子的快速Thouless泵浦,突破了绝热条件的限制,实现了高频调制下的非绝热量子化泵浦。

Comments 8 pages, 4 figures

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AI中文摘要

Thouless泵浦为研究周期性驱动系统中相互作用对拓扑输运的影响提供了一个范例平台。然而,大多数研究受限于绝热条件,这阻碍了在高驱动频率下探索相互作用驱动的新型拓扑态。在这里,我们实验研究了在原子玻色-爱因斯坦凝聚体的动量空间中周期性调制晶格上实现的Thouless泵浦中相互作用与调制频率之间的相互作用。我们观察到中等相互作用下物质波孤子的快速Thouless泵浦,这在非相互作用或弱相互作用区域中没有对应物。在相互作用诱导的拓扑相变边界之外,孤子的非绝热量化泵浦在高调制频率下出现在广泛的相互作用范围内,与理论计算吻合良好,而孤子在低频绝热泵浦区域中保持俘获。我们的工作为加速驱动量子系统中的拓扑输运和设计快速拓扑器件开辟了新途径。

英文摘要

Thouless pumping provides a paradigmatic platform for studying the effects of interactions on topological transport in periodically driven systems. However, most studies have been constrained by adiabatic conditions, which preclude exploration of interaction-driven novel topological states at high driving frequencies. Here, we experimentally investigate the interplay between interaction and modulation frequency in Thouless pumping realized in a periodically modulated lattice in momentum space of atomic Bose-Einstein condensate. We observe fast Thouless pumping of matterwave solitons at intermediate interactions, with no counterpart in the non- or weakly interacting regimes. Beyond the boundary of topological phase transition induced by interaction, nonadiabatic quantized pumping of solitons emerges at high modulation frequencies over a broad interaction range, in good agreement with theoretical calculations, while the solitons remain trapped in the low-frequency adiabatic pumping regime. Our work opens new avenues for accelerating topological transport in driven quantum systems and engineering fast topological devices.

2606.03016 2026-06-03 cond-mat.soft cond-mat.mes-hall math-ph math.MP

Attractive Hopfions and Bimerons in Thin Films of Chiral Magnets: Cluster Formation and Lattice Instability in the Conical Phase

手性磁体薄膜中的吸引型霍普夫子与双半子:锥形态中的团簇形成与晶格不稳定性

Andrey O. Leonov, Takayuki Shigenaga

AI总结 研究手性磁体薄膜中双半子和霍普夫子在锥形态背景下的能量、相互作用及有序倾向,发现吸引相互作用导致团簇形成但无稳定长程有序。

Comments 19 pages, 11 figures

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AI中文摘要

我们研究了在具有锥形态背景态的手性磁体和手性液晶薄膜中,双半子(第二类胆甾相指状结构,CF-2)和霍普夫子的能量学、相互作用和有序倾向。尽管孤立双半子相对于锥形态具有正本征能量,但通过其正能量壳(即相对于锥形态形成的中间区域)的重构和部分重叠,它们发展出吸引相互作用。这种吸引促进了束缚对和扩展双半子链的形成,即使在周期双半子晶格不再热力学稳定的参数区间也是如此。将分析扩展到三维,我们证明双半子圆化为霍普夫子使其能量有限,并产生一个与胆甾相指状结构稳定性范围密切相关的明确亚稳态窗口。孤立霍普夫子同样在锥形态内表现出吸引相互作用,导致六角有序团簇的形成。这种吸引源于有利和不利扭曲区域之间的竞争,以及锥形态背景所施加的壳结构的能量代价。尽管存在吸引对势和团簇形成,我们证明六角霍普夫子晶格并不表现出平衡晶格周期。相反,系统演化到锥形态螺旋或CF-1相(第一类胆甾相指状结构)逐渐侵入孤子间区域的状态,从而阻止结晶。我们的结果揭示了吸引但无稳定长程有序的机制,并阐明了手性磁体和液晶薄膜中拓扑、约束和锥形态挫败之间的相互作用。

英文摘要

We investigate the energetics, interactions, and ordering tendencies of bimerons (cholesteric fingers of the second type, CF--2) and hopfions in thin films of chiral magnets and chiral liquid crystals hosting a conical background state. Although isolated bimerons possess positive eigen-energy with respect to the conical phase, they develop an attractive interaction mediated by the restructuring and partial overlap of their positive-energy shells, i.e., intermediate regions formed relative to the conical state. This attraction promotes the formation of bound pairs and extended bimeron chains, even in parameter regimes where a periodic bimeron lattice is no longer thermodynamically stable. Extending the analysis to three dimensions, we show that circularization of bimerons into hopfions renders their energy finite and gives rise to a well-defined metastability window closely linked to the stability range of cholesteric fingers. Isolated hopfions likewise exhibit an attractive interaction within the conical phase, leading to the formation of hexagonally ordered clusters. The attraction originates from the competition between favorable and unfavorable twist regions and from the energetic cost of the shell structures imposed by the conical background. Despite the presence of attractive pair potentials and cluster formation, we demonstrate that hexagonal hopfion lattices do not exhibit an equilibrium lattice period. Instead, the system evolves toward states in which the conical spiral or the CF--1 phase (cholesteric fingers of the first type) progressively invade the inter-soliton regions, thereby preventing crystallization. Our results reveal a regime of attraction without stable long-range order and clarify the interplay between topology, confinement, and conical-phase frustration in chiral magnet and liquid-crystal thin films.

2606.02999 2026-06-03 cond-mat.dis-nn

Relaxation of the Random Site Coulomb glass Model in Two Dimensions

二维随机位点库仑玻璃模型的弛豫

Preeti Bhandari, Vikas Malik

AI总结 通过平均场近似计算线性动力学矩阵的特征值分布,研究了二维随机位点库仑玻璃模型在密度、无序和局域长度影响下的弛豫动力学,发现系统经历快速弛豫后,单粒子态密度耗尽导致幂律衰减,最终遵循指数衰减律,弛豫时间与最小特征值成反比,且随密度降低或无序增加而延长。

Comments 8 pages, 11 figures

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Journal ref
Phys. Rev. E 113, 064107 (2026)
AI中文摘要

本研究探讨了材料密度、位点能量无序和局域长度对半填充二维随机位点库仑玻璃模型弛豫动力学的影响。为了探索弛豫规律,我们使用平均场近似计算了线性动力学矩阵的特征值分布。我们的发现表明,系统最初通过降低能量的跃迁经历快速弛豫。费米能级附近单粒子态密度的耗尽导致缓慢弛豫,涨落按照幂律衰减。随后,系统在特定时间(定义为弛豫时间)后遵循指数衰减律,该时间与动力学矩阵的最小特征值成反比。随着系统密度降低,弛豫速率减慢,导致弛豫时间增加。在恒定密度和局域长度下,位点能量无序的增加导致更长的弛豫时间。特征值谱的很大一部分不受影响,表明局域长度的减小与无序增加同时发生,可能在观察到的缓慢动力学中起着同样重要的作用。

英文摘要

This study investigates the influence of material density, disorder in onsite energies, and localization length on relaxation dynamics within a two-dimensional random site Coulomb glass model at half-filling. To explore relaxation laws, we calculate the eigenvalue distribution of the linear dynamical matrix using mean-field approximations. Our findings indicate that the system initially undergoes rapid relaxation through energy-lowering transitions. The depletion of the single-particle density of states (DOS) near the Fermi level leads to slow relaxation, with fluctuations diminishing according to a power law. Subsequently, the system adheres to an exponential decay law after a specific period, defined as the relaxation time, which is inversely related to the minimum eigenvalue of the dynamical matrix. As the density of the system decreases, the relaxation rate slows down, resulting in an increase in the relaxation time. For a constant density and localization length, an increase in the disorder of onsite energies results in a longer relaxation time. A significant portion of the eigenvalue spectrum remains unaffected, suggesting that a reduction in localization length concurrent with increased disorder may play an equally vital role in the slow dynamics observed.

2606.02988 2026-06-03 cond-mat.quant-gas

Effective scatterings and universal clusters of heteronuclear ultracold mixtures in quasi-low dimensions

准低维异核超冷混合物的有效散射与普适团簇

Tingting Shi, Xiaoling Cui

AI总结 研究准低维中异核原子有效s波散射参数,并利用其计算普适(1+N)团簇的结合能,为实验观测提供途径。

Comments 15 pages, 4 figures

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AI中文摘要

我们研究了在准低维中谐波约束的两个异核原子的有效s波散射,其中原子具有不等质量并受到不同的约束频率。由此得到的低维有效散射参数,包括散射长度和有效范围,被表示为三维散射参数和约束强度的函数。以实际的Li-K和Li-Cr混合物为例,我们进一步利用有效散射参数计算了准低维中普适$(1+N)$团簇的结合能。我们的发现为在低维异核超冷系统中实际观测普适团簇及其相关的多体相提供了一条有前景的途径。

英文摘要

We study the effective s-wave scattering of two heteronuclear atoms harmonically confined in quasi-low dimensions, where the atoms have unequal masses and are subject to different confinement frequencies. The resulting effective scattering parameters in low dimensions, including scattering length and effective range, are derived as functions of three-dimensional scattering parameters and confinement strengths. Using realistic Li-K and Li-Cr mixtures as examples, we further compute the binding energies of universal $(1+N)$ clusters in quasi-low dimensions using the effective scattering parameters. Our findings suggest a promising pathway for practically observing universal clusters and their associated many-body phases in low-dimensional ultracold heteronuclear systems.

2606.02987 2026-06-03 cond-mat.quant-gas quant-ph

Scattering and Bound States of Two Heteronuclear Ultracold Atoms in a Quasi-Two-Dimensional Confinement

准二维约束中两个异核超冷原子的散射和束缚态

B. Wang, F. Yang, P. Zhang

AI总结 本文精确求解了准二维几何中异核超冷原子的两体问题,推导了二维散射长度、有效力程参数和束缚态能量,并揭示了纵向质心与相对运动耦合可诱导多重二维散射共振,从而可用于调控有效二维原子间相互作用。

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AI中文摘要

我们求解了准二维(quasi-2D)几何中异核超冷原子的两体问题。准二维约束由沿纵向($z$方向)的谐振势实现,两个原子的阱频不同,这与当前许多异核超冷气体实验一致。因此,纵向质心(CoM)运动与相对运动耦合,这显著复杂化了两体问题。我们精确求解了该问题,并推导了二维散射长度$a_{\rm 2D}$、二维有效力程参数$R_{\rm 2D}$以及束缚态能量,它们作为两个原子在自由三维(3D)空间中的$s$波散射长度和有效力程的函数。我们表明,纵向质心与相对运动之间的耦合可以诱导多重二维散射共振。在这些共振附近,$a_{\rm 2D}$随3D散射参数快速变化,而$R_{\rm 2D}$显著增强。由于准二维超冷气体中的有效成对相互作用由两体散射振幅和束缚态能量决定,我们的结果可用于通过调节约束频率和3D散射参数来操纵准二维异核超冷气体中的有效二维原子间相互作用。

英文摘要

We solve the two-body problem of ultracold heteronuclear atoms in a quasi-two-dimensional (quasi-2D) geometry. The quasi-2D confinement is realized by a harmonic trap along the longitudinal ($z$-) direction, with different trap frequencies for the two atoms, as in many current experiments on ultracold heteronuclear gases. As a consequence, the longitudinal center-of-mass (CoM) motion is coupled to the relative motion, which significantly complicates the two-body problem. We solve this problem exactly and derive the 2D scattering length $a_{\rm 2D}$, the 2D effective range parameter $R_{\rm 2D}$, and the bound-state energies, as functions of the $s$-wave scattering length and effective range of the two atoms in free three-dimensional (3D) space. We show that multiple 2D scattering resonances can be induced by the coupling between the longitudinal CoM and relative motion. Around these resonances, $a_{\rm 2D}$ varies rapidly with the 3D scattering parameters, while $R_{\rm 2D}$ is strongly enhanced. Since the effective pairwise interaction in quasi-2D ultracold gases is determined by i.e., the two-body scattering amplitudes and bound-state energies, our results can be used for manipulating the effective 2D interatomic interaction in quasi-2D ultracold heteronuclear gases by tuning the confinement frequencies and the 3D scattering parameters.

2606.02931 2026-06-03 cond-mat.mes-hall cond-mat.mtrl-sci

Second-Order Synaptic Memory using Inherent Plasticity of Moiré Superlattices

利用莫尔超晶格的内在可塑性实现二阶突触记忆

Tanweer Ahmed, Kenji Watanabe, Takashi Taniguchi, Fèlix Casanova, Luis E. Hueso

AI总结 本文通过扭曲双层石墨烯莫尔超晶格中的电子滞后和可塑性,结合二阶非线性电响应,实现了纯碳基材料中的二阶突触记忆器件。

Comments This is a pre-peer review version. The published version of record and the supporting info can be obtained from the publisher's website using the url: https://doi.org/10.1002/adma.202509837

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AI中文摘要

在单元素量子材料中以电子方式实现突触功能是一个基本挑战,因为传统方法依赖于引入外在电荷陷阱或极性组分。在这里,我们展示了由纯碳组成的扭曲双层石墨烯(tDBLG)莫尔超晶格,在存在扭曲角无序的情况下表现出电子滞后和可塑性。莫尔尺度上的反演对称性破缺还通过无序介导的外在机制产生了二阶非线性电响应。这种二阶非线性在符号和幅度上均可通过改变载流子浓度和垂直位移场高度调节。我们利用电子可塑性和二阶非线性的共存来实现二阶突触记忆器件。我们的发现确立了应变莫尔碳系统作为节能神经形态计算的有力新平台,证明了复杂的电子功能可以纯粹从单元素材料中的对称性破缺物理中涌现。

英文摘要

Achieving synaptic functionality electronically in a single-element quantum material is a fundamental challenge, as conventional methods rely on the introduction of extrinsic charge-traps or polar components. Here, we demonstrate that twisted double bilayer graphene (tDBLG) moiré superlattices, composed purely of carbon, exhibit electronic hysteresis and plasticity in presence of twist-angle disorder. Inversion symmetry breaking at the moiré length scales also gives rise to second-order nonlinear electrical response via disorder-mediated extrinsic mechanisms. Such second-order nonlinearity is highly tunable in both sign and magnitude by varying carrier concentration and vertical displacement field. We harness the coexistence of electronic plasticity and second-order nonlinearity to realize a second-order synaptic memory device. Our findings establish strained moiré carbon systems as a powerful new platform for energy-efficient neuromorphic computing, demonstrating that complex electronic functionality can emerge purely from symmetry breaking physics in a single-element material.

2606.02930 2026-06-03 cond-mat.str-el cs.NA math.NA quant-ph

Fast Tensor Network Imaginary Time Evolution by Implicit Stepping on Logarithmic Grids

基于对数网格隐式步进的快速张量网络虚时演化

John P. Zima, E. Miles Stoudenmire, Steven R. White, Olivier Parcollet, Jason Kaye

AI总结 提出一种利用对数时间网格和A-稳定隐式时间步进方法,高效实现矩阵乘积态虚时演化的新方案,显著减少时间步数并验证了在自旋链和安德森杂质模型中的加速效果。

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AI中文摘要

我们提出了一种新方法,用于高效实现由矩阵乘积态(MPS)表示的量子多体波函数的虚时演化。我们首先证明对数时间网格足以解析长虚时动力学,与标准方法相比,时间步数呈指数减少。然后我们证明,对于常微分方程,A-稳定隐式时间步进方法允许任意时间步长下的稳定传播。得到的方案仅需要矩阵-向量乘积和线性求解,这是MPS工具箱中的标准操作。我们通过两个例子验证了我们的方法:一个海森堡自旋链,我们用它来展示相比于具有均匀时间步长的标准时间相关变分原理方法,加速了几个数量级;以及一个具有金属浴的单站点安德森杂质模型,对于该模型,传播到大虚时允许观察到近藤温度对相互作用强度的指数依赖。

英文摘要

We present a new method for the efficient imaginary time evolution of quantum many-body wavefunctions represented by matrix product states (MPS). We first show that logarithmic time grids are sufficient to resolve long imaginary time dynamics, yielding an exponential reduction in the number of time steps compared with standard approaches. We then show that A-stable implicit time-stepping methods for ordinary differential equations allow stable propagation for any time step size. The resulting scheme requires only matrix-vector products and linear solves, standard operations in the MPS toolbox. We validate our approach with two examples: a Heisenberg spin chain, which we use to demonstrate a speedup of several orders of magnitude over the standard time-dependent variational principle method with uniform time steps, and a single-site Anderson impurity model with a metallic bath, for which propagation to large imaginary times allows one to observe the exponential dependence of the Kondo temperature on the interaction strength.

2606.02858 2026-06-03 cond-mat.mes-hall cond-mat.mtrl-sci

Negative temperature coefficient of Gilbert damping in magnetic bilayers

磁性双层中吉尔伯特阻尼的负温度系数

Lulu Cao, Yuting Gong, Xianyang Lu, Yongbing Xu, Ya Zhai, Jing Wu, Roy W. Chantrell, Richard F. L. Evans

AI总结 通过原子模拟和实验测量,发现Py/Nd双层中吉尔伯特阻尼随温度升高而降低,源于界面自旋泵浦增强阻尼及弛豫过程中界面与体磁化的动态分离,且可通过改变Nd覆盖层厚度调控温度依赖性。

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AI中文摘要

磁性材料的吉尔伯特阻尼是决定自旋电子器件开关速度和能量耗散的重要磁性参数。在简单金属中,本征吉尔伯特阻尼随温度升高而增大,并在居里温度附近由于自旋涨落而发散。本文展示了原子模拟和实验测量,显示Py/Nd双层中出现了相反的行为,即吉尔伯特阻尼随温度升高而降低。该效应源于自旋泵浦导致的界面阻尼增强,其中高温引起弛豫过程中界面与体磁化的动态分离。此外,阻尼的温度依赖性可通过改变Nd覆盖层厚度进行调控。我们的发现提出了一种新的自旋电子效应,可用于调控纳米材料和器件的动态特性,以提高能效或改善开关动力学。

英文摘要

The Gilbert damping of magnetic materials is an important magnetic parameter that determines the switching speed and energy dissipation of spintronic devices. In simple metals, the intrinsic Gilbert damping increases with temperature and diverges near the Curie temperature as a result of spin fluctuations. Here we present atomistic simulations and experimental measurements showing surprising and opposite behavior in Py/Nd bilayers, where the Gilbert damping decreases with increasing temperature. The effect arises because of the enhanced damping at the interface as a result of spin pumping, where elevated temperatures cause a dynamic separation of the interfacial and bulk magnetization during relaxation. Furthermore, the temperature dependence of the damping can be controlled by varying the thickness of the Nd capping layer. Our findings present a new spintronic effect that can be used to modify the dynamic properties of nanoscale materials and devices for enhanced energy efficiency or with improved switching dynamics.

2606.02853 2026-06-03 cond-mat.soft

Undulatory forcing of an intruder through granular media: effects of frequency and packing fraction

颗粒介质中侵入体的波动驱动:频率和填充分数的影响

Douglas Daniel de Carvalho, Erick de Moraes Franklin

AI总结 通过离散数值模拟,研究侵入体在颗粒介质中受方向振荡力作用下的运动,发现填充分数和频率显著影响运动模式,存在最优频率最小化通过时间,并基于系统弹性提出模型。

Comments Accepted manuscript for Physical Review E, 113, 055422 (2026)

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Journal ref
Physical Review E, 113, 055422, 2026
AI中文摘要

我们研究了侵入体在受到给定频率振荡的强制力作用下在颗粒中的运动。为此,我们使用了离散数值模拟,其中侵入体是一个较大的圆盘,对其施加方向振荡的力,而颗粒由较小的圆盘组成。所有圆盘放置在有基底摩擦的表面上,可以在其上滑动,系统在滑动方向受限,我们改变了系统的填充分数、振荡频率和力的大小。结果表明,侵入体的运动是间歇性的且非常复杂,取决于填充分数和振荡频率:它可以侧向移动同时缓慢前进,可以在开始移动之前和/或之后长时间被阻塞,或者可以在给定时间后完全被阻塞。有趣的是,我们发现当系统填充分数高于某个阈值时,位移速度要高得多,这与直觉相反。结果表明,存在一个最优频率,可以在某些填充分数范围内最小化通过时间,我们提出了一个基于系统弹性的模型来解释这一行为,并与数值模拟结果一致。我们的发现为如何更好地利用振荡运动在颗粒介质中移动物体提供了新的见解。

英文摘要

We investigate the motion amid grains of an intruder undergoing an imposed force that oscillates with a given frequency. For that, we made use of discrete numerical simulations where the intruder was a larger disk on which a force oscillating in direction was applied, and the grains consisted of smaller disks. All disks were placed on a surface with basal friction over which they could slide, the system was confined in the sliding directions, and we varied the system packing fraction, oscillation frequency, and magnitude of the forcing. The results show intermittent and very complex motions of the intruder depending on both the packing fraction and frequency of oscillation: it can move sideways while slowly progressing forward, it can be blocked during a long period after and/or before start moving, or it can simply be blocked after a given time. Interestingly, we find that the displacement velocity is much higher when the system packing fraction is above a given threshold, contrary to intuition. The results show that there is an optimal frequency that minimizes the transit time for some ranges of packing fraction, and we propose a model based on the system elasticity that explains this behavior and agrees with the numerical simulations. Our findings shed new light on how to better explore oscillating motion to move objects within granular media.

2606.02851 2026-06-03 cond-mat.mtrl-sci cond-mat.mes-hall

Shift current conductivity in monolayer SnS: a tight-binding analysis

单层SnS中的位移电流电导率:紧束缚分析

Yuki Kusunoki, Tomoaki Kameda, Katsunori Wakabayashi

AI总结 基于第一性原理导出的紧束缚模型,通过比较短程和长程跳跃模型,揭示了单层SnS中位移电流电导率的关键特征,并提供了理解和设计二维材料体光伏效应的清晰框架。

Comments 12 pages; 10 figures

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AI中文摘要

我们使用从第一性原理计算导出的有效紧束缚模型,研究了单层SnS中的体光伏效应。通过比较短程和长程跳跃模型,我们表明位移电流电导率的基本特征可由一个最小模型捕获。将位移电流分解为跃迁强度和位移矢量,从而能够识别主导的带间跃迁。比较表明,长程跳跃过程定量地改变了峰位和幅度,而短程模型保留了非线性响应的特征低能结构。我们的发现为理解和设计二维材料中的体光伏效应提供了一个透明的框架。

英文摘要

We investigate the bulk photovoltaic effect in monolayer SnS using an effective tight-binding model derived from first-principles calculations. By comparing short-range and long-range hopping models, we show that the essential features of the shift current conductivity are captured by a minimal model. The shift current is decomposed into transition intensity and shift vector, enabling identification of dominant interband transitions. The comparison reveals that long-range hopping processes quantitatively modify the peak positions and magnitudes, while the short-range model retains the characteristic low-energy structure of the nonlinear response. Our findings provide a transparent framework for understanding and designing bulk photovoltaic effects in two-dimensional materials.

2606.02845 2026-06-03 cond-mat.str-el

Phase transitions through excited-state level crossings and topological indicators: the case of the XXZ chain with staggered Ising interaction

通过激发态能级交叉和拓扑指标的相变:交错伊辛相互作用的XXZ链

B. F. Márquez, K. Hallberg, A. A. Aligia

AI总结 本文结合精确对角化,利用激发态能级交叉和拓扑指标两种方法,确定了具有交错伊辛相互作用的XXZ链的相图,并比较了两种方法的准确性和适用性。

Comments 8 pages, 3 figures

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AI中文摘要

我们结合两种基于精确对角化的方法,确定了具有交错伊辛相互作用和均匀横向交换的自旋-$1/2$ XXZ链的相图。该模型实现了由交替伊辛相互作用产生的奈尔序和键二聚化相之间的竞争。确定相边界的最简单方法是使用基于广义位置算子的拓扑指标。我们表明,总体上,拓扑指标的玻色化和数值结果一致。第二种方法基于激发态能级交叉,并由共形场论证明。尽管交替伊辛相互作用导致平移对称性部分丧失,我们发现后一种方法能够精确确定奈尔相和二聚化相之间的边界。相反,虽然拓扑指标的跳跃提供了定性正确的相图,但当我们使用场论论证表明,当相变一侧的能隙非常小(或关联长度非常大)时,其准确性会受到影响。两种方法的结合为计算一维关联模型的相图提供了一种比其他广泛使用的传统方法更有效的方式。

英文摘要

We combine two ways of determining the phase diagram of the spin-$1/2$ XXZ chain with a staggered Ising interaction and uniform transverse exchange, based on exact diagonalization. The model realizes a competition between Néel order and bond-dimerized phases generated by the alternating Ising interaction. The simplest approach to determine the phase boundaries is to use topological indicators based on generalized position operators. We show that in general, the bosonized and numerical results for the topological indicators agree. The second is based on crossings of excited energy levels and justified by conformal-field theory. In spite of the partial loss of translational symmetry caused by the alternating Ising interaction, we find that the latter method provides an accurate determination of the boundary between Néel and dimerized phases. Instead, while the jumps of a topological indicator provide a qualitatively correct phase diagram, its accuracy is affected when the gap is very small (or the correlation length very large) at one side of the transition, as we show using field-theoretical arguments. The combination of both methods provides a more efficient way of calculating phase diagrams for correlated one-dimensional models than other widely used conventional approaches.

2606.02838 2026-06-03 cond-mat.str-el cond-mat.supr-con

The pseudogap in high-$T_c$ superconductors from SU(2) gauge symmetry and dynamic correlation effects

高$T_c$超导体中来自SU(2)规范对称性和动态关联效应的赝能隙

I. A. Goremykin, A. A. Katanin

AI总结 利用SU(2)规范理论和动态平均场理论,研究了二维Hubbard模型在欠掺杂区域的谱性质,揭示了空穴口袋内外阻尼不对称性及费米弧的形成机制。

Comments 15 pages, 7 figures

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AI中文摘要

我们考虑二维Hubbard模型的谱性质,该模型描述高$T_c$化合物的电子性质,采用SU(2)规范理论,该理论假设电子自由度分离为自旋子和电荷子子系统。我们使用动态平均场理论(DMFT)方法描述电荷子子系统中的磁长程序,同时处理该状态之上的自旋子涨落。我们表明,由长波磁涨落补充的DMFT对于描述空穴口袋内部和外部区域之间阻尼的不对称性以及由此产生的欠掺杂区域(特别是在低空穴掺杂下)费米弧的形成至关重要。电荷子子系统中潜在的空穴口袋可以与量子振荡测量中观察到的空穴口袋相关联。

英文摘要

We consider the spectral properties of the two-dimensional Hubbard model, describing the electronic properties of high-$T_c$ compounds, within the SU(2) gauge theory, which assumes the separation of electronic degrees of freedom into those of spinon and chargon subsystems. We use the dynamic mean-field theory (DMFT) approach to describe magnetic long-range order in the chargon subsystem while also treating spinon fluctuations on top of this state. We show that DMFT supplemented by long-wavelength magnetic fluctuations is essential for describing the asymmetry in the damping between the inner and outer regions of the hole pockets and the resulting formation of Fermi arcs in the underdoped regime, especially at low hole doping. The underlying hole pockets in the chargon subsystem can be associated with those observed in quantum oscillation measurements.

2606.02808 2026-06-03 cond-mat.dis-nn

Structural glasses model using disorder fields: the boson peak from local ground states

使用无序场的结构玻璃模型:来自局部基态的玻色峰

M. M. Balbino, I. P. de Freitas, A. M. S. Macedo, G. Krein, N. F. Svaiter

AI总结 通过将静态密度涨落场与乘性淬火无序耦合,并利用平均自由能中的有效作用量识别大量亚稳态和基态,解释了结构玻璃光谱密度中玻色峰特征贡献的出现,并建立了双曲型微分方程与平均自由能中多个基态之间的联系。

Comments 13 pages, 0 figures

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AI中文摘要

我们展示了结构玻璃光谱密度中玻色峰特征贡献的出现。为了模拟玻璃态,我们考虑了与乘性淬火无序耦合的静态密度涨落场。通过对所有无序实现进行系综平均,得到了平均自由能的泛函级数表示。在玻璃态物质的平均自由能的级数表示中,我们在函数空间中识别出有效作用量。这些有效作用量呈现出大量的亚稳态和基态。文献中广泛讨论的作为过冷液体到玻璃态物质转变描述的随机一级转变在我们的形式中自然出现。我们建立了使用随机系数的双曲型微分方程与平均自由能中多个基态的存在之间的联系。这种联系使我们能够研究此类非晶材料中的涌现激发。

英文摘要

We show the emergence of a contribution characteristic of the boson peak in the spectral density of structural glasses. To model the vitreous state, we consider static density-fluctuation fields coupled to a multiplicative quenched disorder. Performing an ensemble average over all disorder realizations, a functional series representation of the average free energy is obtained. In this series representation of the average free energy for the glassy state of matter, we identify in the function space effective actions. These effective actions present a large number of metastable states and ground states. Random first-order transition, widely discussed in the literature as a description of the transition from the supercooled liquid to the glassy state of matter, emerges naturally in our formalism. We establish the connection between the use of hyperbolic differential equations with random coefficients and the presence of many ground states in the average free energy. This connection allows us to study emergent excitations in such amorphous materials.

2606.02794 2026-06-03 cond-mat.dis-nn cond-mat.str-el cs.CC quant-ph

Scaling Laws for Neural-Network Quantum States

神经网络量子态的缩放定律

Riccardo Rende, Alessandro Sinibaldi, Luciano Loris Viteritti, Roeland Wiersema, Antoine Georges, Giuseppe Carleo

AI总结 通过变压器波函数近似三角和方形晶格上$J_1$-$J_2$海森堡模型的基态,发现$V$-score随训练计算量呈幂律衰减,且缩放指数随阻挫程度系统性地减小,从而建立了缩放定律作为评估变分拟设的通用框架。

Comments 7 pages, 5 figures

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AI中文摘要

缩放定律,即现代神经网络中损失、架构大小和计算量之间的幂律关系,提供了一种量化学习问题复杂性的方法,其中控制损失衰减的指数反映了额外资源如何快速转化为精度的提升,从而表明目标的学习难度。一个类似的框架是否能够表征物理问题的复杂性仍然是一个开放问题。我们针对神经网络量子态(一种用于强关联量子多体系统的主要变分方法)研究了这一问题。通过使用变压器波函数近似三角形和方形晶格上多达$20\times 20$个格点的$J_1$-$J_2$海森堡模型的基态,我们发现变分态精度的度量$V$-score随训练计算量呈幂律衰减。在适当的计算量重标度下,不同系统大小的结果坍缩到一条曲线上,类似于临界现象中的标度坍缩。所得的幂律在很好的近似下与格点数无关,表明变压器拟设对于所考虑的系统是尺寸一致的。该指数随阻挫程度系统地减小,将其确定为基态表示难度的定量度量,并建立了缩放定律作为评估变分拟设的通用框架。

英文摘要

Scaling laws, the power-law relations between loss, architecture size, and compute observed in modern neural networks, offer a quantitative way to characterize the complexity of a learning problem, with the exponent governing the decay of the loss reflecting how rapidly additional resources translate into improved accuracy, and thus how hard the target is to learn. Whether an analogous framework can characterize the complexity of physical problems remains open. We address this question for Neural-Network Quantum States, a leading variational approach for strongly correlated quantum many-body systems. Using transformer wave functions to approximate ground states of the $J_1$-$J_2$ Heisenberg model on triangular and square lattices with up to $20\times 20$ sites, we find that the $V$-score, a measure of accuracy of a variational state, decays as a power law in training compute. Under an appropriate rescaling of compute, results for different system sizes collapse onto a single curve, analogous to scaling collapse in critical phenomena. The resulting power law is, to a good approximation, independent of the number of sites, showing that the transformer Ansatz is size-consistent for the systems considered. The exponent decreases systematically with frustration, identifying it as a quantitative measure of representational difficulty of the ground state and establishing scaling laws as a general framework for benchmarking variational ansätze.

2606.02793 2026-06-03 cond-mat.str-el cond-mat.stat-mech

Skyrmion and meron phases induced by spin-phonon coupling

自旋-声子耦合诱导的斯格明子和梅伦相

E. Iroulart, F. A. Gómez Albarracín, H. Diego Rosales

AI总结 通过蒙特卡洛模拟研究二维斯格明子模型中自旋-声子耦合对磁相互作用和自旋纹理的影响,发现爱因斯坦位点-声子模型稳定了斯格明子晶体并诱导了梅伦-反梅伦晶体和混合斯格明子-双斯格明子相,且强耦合导致六角晶格畸变为四方晶格。

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AI中文摘要

在手性磁体中,磁斯格明子通常通过外磁场下交换相互作用和Dzyaloshinskii-Moriya相互作用的竞争来稳定,而晶格自由度的作用相对较少受到关注。在这里,我们研究了自旋-声子(SP)耦合如何修改磁相互作用以及由此产生的二维斯格明子模型在正方晶格中的自旋纹理。使用蒙特卡洛模拟,我们比较了描述SP耦合的两个简化模型:爱因斯坦位点-声子(ESP)和键-声子(BP)模型。我们发现,ESP耦合在无耦合模型中拓扑平庸的场区域稳定了斯格明子晶体,并诱导了额外的纹理,包括梅伦-反梅伦(M-aM)晶体和混合斯格明子-双斯格明子(SkX-Bm)相。此外,对于足够强的声子耦合,传统的三重$\textbf{q}$六角斯格明子晶格畸变为双重$\textbf{q}$正方斯格明子晶格。总体而言,我们的结果表明晶格效应提供了一种调节拓扑磁性相的简单机制。

英文摘要

In chiral magnets, magnetic skyrmions are typically stabilized by the competition between exchange and Dzyaloshinskii-Moriya interactions under an external magnetic field, while the role of lattice degrees of freedom has received comparatively less attention. Here we study how spin-phonon (SP) coupling modifies magnetic interactions and the resulting spin textures in a two-dimensional skyrmion model in the square lattice. Using Monte Carlo simulations, we compare two simplified models describing the SP coupling: the Einstein site-phonon (ESP) and bond-phonon (BP) models. We find that ESP coupling stabilizes skyrmion crystals in field regimes that are topologically trivial in the uncoupled model and also induces additional textures, including meron-antimeron (M-aM) crystals and mixed skyrmion-bimeron (SkX-Bm) phases. Furthermore, for sufficiently strong phonon coupling, the conventional triple-$\textbf{q}$ hexagonal skyrmion lattice is distorted into a double-$\textbf{q}$ square skyrmion lattice. Overall, our results show that lattice effects provide a simple mechanism to tune topological magnetic phases.

2606.02770 2026-06-03 cond-mat.supr-con

Early Experiments on Macroscopic Quantum Tunneling

宏观量子隧穿的早期实验

Willem den Boer

AI总结 回顾1980年莱顿大学在射频SQUID中铌点接触的早期实验,这些实验在Clarke等人1985年发表确凿证据前被解释为宏观量子隧穿。

Comments 7 pages,7 figures

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AI中文摘要

在Clarke、Devoret和Martinis于1985年发表宏观量子隧穿(MQT)的确凿证据之前,其他几个小组报告了被解释为MQT的实验结果。按时间顺序,第一个是在1980年,基于1979年在莱顿大学进行的研究。本文回顾了这些在射频超导量子干涉器件(rf SQUID)配置中,于1至4.2 K温度下对低电容铌点接触进行的实验。该研究受到Ivanchenko和Zilberman在1969年关于电流偏置约瑟夫森结中MQT的理论预测以及Leggett在1978年关于含超导弱连接闭合回路中MQT的理论预测的启发。

英文摘要

Before conclusive evidence of Macroscopic Quantum Tunneling, MQT, was published by Clarke, Devoret and Martinis in 1985, several other groups reported experimental results interpreted as MQT. The first, in chronological order, was in 1980 based on studies done at Leiden University in 1979. This paper looks back at these experiments on low capacitance Niobium point contacts in an rf SQUID, radio-frequency Superconducting Quantum Interference Device, configuration at temperatures between 1 and 4.2 K. The research was inspired by the theoretical predictions by Ivanchenko and Zilberman in 1969 on MQT in current-biased Josephson junctions and by Leggett in 1978 on MQT in closed loops with a superconducting weak link.

2606.02766 2026-06-03 cond-mat.str-el cond-mat.stat-mech

Spin-$s$ model with competing interactions on diamond-decorated lattices

菱形装饰晶格上具有竞争相互作用的自旋-$s$ 模型

D. V. Dmitriev, V. Ya. Krivnov, O. A. Vasilyev

AI总结 本文通过精确分析和数值方法,研究了菱形装饰晶格上铁磁-反铁磁自旋-$s$ 模型的基态性质、磁化和低温热力学,揭示了由双线性 Heisenberg 和高阶交换相互作用导致的丰富相图、宏观简并和残余熵,并指出其在超低温冷却和量子热机中的潜在应用。

Comments 33 pages, 7 figures

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AI中文摘要

我们研究了具有理想菱形单元的菱形装饰晶格上铁磁-反铁磁自旋-$s$ 模型的基态性质、磁化和低温热力学,其中包含对角自旋-$\sigma$ 之间的双线性 Heisenberg 和高阶交换相互作用。每个菱形对角线上复合自旋的局域守恒使得精确分析成为可能。对于纯 Heisenberg 情况,随着耦合比的变化,系统经历一系列 $2\sigma$ 个相变,在单体-二聚体(MD)、亚铁磁(Ferri)和铁磁(F)相之间转变,并具有不同的最优复合自旋值。在存在高阶相互作用的情况下,存在一个多临界点,其中所有可能的复合自旋值的态都是简并的,导致基态简并度最大。详细研究了具有双线性和双二次相互作用的 $s=\sigma=1$ 情况。其相图包含三个相——F、Ferri 和 MD,它们在一个三相点相遇。在相边界上,基态变得宏观简并。对于菱形链,我们精确计算了基态简并度;对于更高维度,问题映射到键逾渗框架,并通过数值求解。每个自旋的残余熵达到最大值的 $60\%$,在三相点处达到峰值。在外磁场中的低温磁化曲线表现出平台和跳跃。激发谱在 MD 相中有能隙,在 F 相中无能隙,在 Ferri 相中类似于 Lieb-Mattis 亚铁磁体。高残余熵表明其在超低温冷却和量子热机中的潜在应用。

英文摘要

We investigate the ground state properties, magnetization, and low-temperature thermodynamics of the ferromagnetic-antiferromagnetic spin-$s$ model on diamond-decorated lattices with ideal diamond units, incorporating bilinear Heisenberg and higher-order exchange interactions between diagonal spins-$σ$. Local conservation of the composite spin on each diamond diagonal enables exact analysis. For the pure Heisenberg case, the system undergoes a series of $2σ$ transitions between monomer-dimer (MD), ferrimagnetic (Ferri) and ferromagnetic (F) phases with different optimal composite spin values as the coupling ratio varies. In the presence of higher-order interactions, a multicritical point exists where the states with all possible values of composite spin are degenerate, leading to maximal ground state degeneracy. The case $s=σ=1$ with bilinear and biquadratic interactions is studied in detail. Its phase diagram comprises three phases - F, Ferri and MD, which meet at a triple point. On the phase boundaries, the ground state becomes macroscopically degenerate. For the diamond chain, we calculate the ground state degeneracy exactly; for higher dimensions, the problem maps onto a bond percolation framework, solved numerically. The residual entropy per spin reaches up to $60\%$ of the maximal value, peaking at the triple point. Low-temperature magnetization curves in external magnetic fields exhibit plateaus and jumps. The excitation spectrum is gapped in the MD phase, gapless in the F phase, and resembles that of the Lieb-Mattis ferrimagnet in the Ferri phase. The high residual entropy suggests potential applications in ultra-low-temperature cooling and quantum thermal machines.

2606.02760 2026-06-03 cond-mat.mtrl-sci cond-mat.str-el

Optoelectronics and Magnetic properties calculation of RE$_2$MnNiO$_6$ (RE=La-Lu,Y) using Density Functional Theory

基于密度泛函理论的RE2MnNiO6 (RE=La-Lu,Y) 光电与磁性计算

Debidutta Pradhan

AI总结 采用DFT+U方法研究RE2NiMnO6双钙钛矿系列,通过比较4f电子作为冻结芯态与价态的处理,揭示4f占据与八面体畸变对磁性和光电性能的协同影响。

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AI中文摘要

RE2NiMnO6 (RE = La-Lu) 有序双钙钛矿氧化物家族具有交替的NiO6和MnO6八面体共角网络,其电子和磁基态通过镧系收缩由A位离子半径系统调控。RE 4f电子的强局域性对密度泛函处理构成根本挑战,但4f与相邻5d (RE) 或3d (Ni, Mn) 态之间的杂化是整个系列交换相互作用和光电响应的关键。我们在DFT+U框架下对代表性RE2NiMnO6化合物的电子结构、晶格动力学和光学性质进行了全面的第一性原理研究。为了理清近藤型4f-d杂化的作用,计算分别将RE 4f电子作为冻结芯态和显式包含在价态中进行,从而直接评估它们对能带结构、介电函数和声子色散的贡献。自旋极化计算揭示了显著的自旋通道不对称性,对于该系列中的某些成员,磁矩高达每公式单元30 μB。结果建立了统一的图像,说明4f占据和八面体畸变如何共同决定该双钙钛矿家族的磁性和光电潜力。

英文摘要

RE$_2$MnNiO$_6$ (RE = La-Lu) family of ordered double-perovskite oxides hosts a corner-sharing network of alternating NiO$_6$ and MnO$_6$ octahedra whose electronic and magnetic ground states are systematically governed by the A-site ionic radius through the lanthanide contraction. The strong localisation of RE 4f electrons poses a fundamental challenge to density-functional treatments, yet the hybridisation between 4f and neighbouring 5d (RE) or 3d (Ni, Mn) states is central to the origin of exchange interactions and optoelectronic response across the series. We present a comprehensive first-principles study of the electronic structure, lattice dynamics, and optical properties of representative RE2NiMnO6 compounds within the DFT+U framework. To disentangle the role of Kondo-type 4f-d hybridisation, calculations are performed with the RE 4f electrons treated both as frozen core states and explicitly in the valence manifold, enabling a direct assessment of their contribution to the band structure, dielectric function, and phonon dispersion. Spin-polarised calculations reveal significant spin-channel asymmetry, with magnetic moments reaching up to 30 $μ$B per formula unit for select members of the series. The results establish a unified picture of how 4f occupancy and octahedral distortion collectively determine the magnetic and optoelectronic potential of this double-perovskite family.

2606.02733 2026-06-03 cond-mat.dis-nn

Coexistence of topologically nontrivial and trivial insulating states in topological Anderson Chern insulator

拓扑安德森陈绝缘体中拓扑非平凡与平凡绝缘态的共存

Bo Yin, Yan Zhang, Anqi Wang, Jie Shen, Zhijun Wang, Quansheng Wu

AI总结 通过密度泛函理论和非平衡格林函数方法研究无序驱动的铁磁单层MnBi4Te7中的拓扑安德森陈绝缘体,发现拓扑非平凡与平凡绝缘态在强无序下共存,并构建了相图。

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AI中文摘要

无序与拓扑之间的相互作用已成为凝聚态物理的核心主题。无序不仅可以破坏拓扑相,还可以诱导拓扑相,拓扑安德森绝缘体(TAI)就是一个例子。在这里,我们表明,类似地,无序可以将清洁极限下时间反演对称性破缺(T-broken)的铁磁(FM)单层MnBi4Te7的量子自旋霍尔态驱动为量子反常霍尔相,称为拓扑安德森陈绝缘体(TACI)。利用密度泛函理论(DFT)和存在无序的非平衡格林函数(NEGF)计算,我们识别了无序诱导的相——包括T-broken TAI、TACI、正常绝缘体等,然后构建了全面的相图。为了区分强无序区域中的多个相,我们进一步使用了自洽玻恩近似(SCBA)计算的态密度,这特别区分了有能隙和无能隙的拓扑相。我们发现哈密顿量的两个有效能带反转在不同的临界无序强度下被抑制;单个反转在有限无序窗口内的存活稳定了TACI。值得注意的是,在强无序下,我们进一步提出了一种零霍尔平台绝缘态,其特征是绝缘体体和受到扩散散射的边缘通道,可以与TACI共存。这种行为与传统的带隙陈绝缘体不同,并提供了清晰的实验特征。

英文摘要

The interplay between disorder and topology has become a central theme in condensed matter physics. Disorder can not only destroy topological phases but also induce them, as exemplified by the topological Anderson insulator (TAI). Here we show that, in close analogy, disorder can drive the clean-limit, time-reversal-broken(T-broken) quantum spin Hall state of ferromagnetic(FM) monolayer MnBi4Te7 into a quantum anomalous Hall phase, which was called topological Anderson Chern insulator (TACI). Using density functional theory (DFT) and nonequilibrium Green's func tion (NEGF) calculations in the presence of disorder, we identify disorder induced phases-including T-broken TAI, TACI, Normal insulator, etc., then construct a comprehensive phase diagram. To discriminate multiple phases in the strong disorder regime, we further use the density of states computed within the self-consistent Born approximation (SCBA), which in particular distinguishes gapped and ungapped topological phases. We find that the two effective band inversions of Hamiltonian are suppressed at distinct critical disorder strengths; the survival of a single inversion over a finite disorder window stabilizes the TACI. Remarkably, at strong disorder, we further propose a zero Hall plateau insulating state characterized by an insulating bulk and edge channels subject to diffusive scattering that can coexist with the TACI. This behavior is distinct from a conventional band-gap Chern insulator and provides a clear experimental signature.

2606.02730 2026-06-03 cond-mat.supr-con cond-mat.mtrl-sci

Anharmonic lattice dynamics and superconductivity in strained bulk and surface niobium

应变块体和表面铌中的非谐晶格动力学与超导电性

Mihir Ranjan Sahoo, Roman Lucrezi, Pedro Nunes Ferreira, Chia-Nien Tsai, Matthew Julian, Rohit P. Prasankumar, Mahmoud I. Hussein, Christoph Heil

AI总结 通过第一性原理计算,研究均匀应变和晶面取向如何调控铌的振动和超导性质,发现应变增强超导转变温度,表面需考虑非谐效应,并识别出最有效的配对声子能量范围。

Comments 14 pages, 10 figures

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AI中文摘要

利用第一性原理计算,我们研究了均匀应变和晶面取向如何改变铌的振动和超导性质。对于块体Nb,拉伸应变强烈软化声子谱并增强电子-声子耦合,使超导转变温度从平衡时的9.5 K提高到约6%晶格膨胀时的14.5 K。对于低指数Nb(001)、Nb(110)和Nb(111)表面,谐波声子计算出现虚频模式,表明非谐晶格效应至关重要。为了有效处理这些效应,我们在块体和板层第一性原理构型上训练了Nb特定的机器学习原子间势,并用于加速随机自洽谐波近似计算,从而获得非谐重整化声子模,再结合密度泛函微扰理论电子-声子矩阵元构建Eliashberg谱函数。在我们考虑的清洁自由站立板层中,Nb(001)表现出最强的电子-声子耦合和最高的计算转变温度10.0 K,而Nb(110)和Nb(111)的配对强度逐渐减弱。最后,通过分析Eliashberg谱函数和泛函导数δT_c/δα²F(ω),我们识别出对超导配对最有效的声子能量范围。我们的结果表明,应变、表面终止和非谐声子重整化为调控Nb中的超导电性提供了互补且相互关联的微观途径。

英文摘要

Using first-principles calculations, we investigate how homogeneous strain and crystallographic surface orientation modify the vibrational and superconducting properties of niobium. For bulk Nb, tensile strain strongly softens the phonon spectrum and enhances the electron--phonon coupling, increasing the superconducting transition temperature from 9.5 K at equilibrium to 14.5 K at $\sim\!6\%$ lattice expansion. For the low-index Nb(001), Nb(110), and Nb(111) surfaces, harmonic phonon calculations exhibit imaginary modes, showing that anharmonic lattice effects are essential. To treat these effects efficiently, we train Nb-specific machine-learning interatomic potentials on bulk and slab first-principles configurations and use them to accelerate stochastic self-consistent harmonic approximation calculations, thereby obtaining anharmonically renormalized phonon modes that are combined with density-functional perturbation theory electron--phonon matrix elements to construct the Eliashberg spectral function. Among the clean free-standing slabs considered here, Nb(001) exhibits the strongest electron--phonon coupling and the highest calculated transition temperature of 10.0 K, while Nb(110) and Nb(111) show progressively reduced pairing strength. Finally, by analyzing the Eliashberg spectral function and the functional derivative $δT_\text{c}/δα^2F(ω)$, we identify the phonon energy ranges most effective for superconducting pairing. Our results show that strain, surface termination, and anharmonic phonon renormalization provide complementary and interrelated microscopic routes for tuning superconductivity in Nb.

2606.02716 2026-06-03 cond-mat.str-el

Two-orbital $e_g$ model with bond-dependent spin-orbit coupling: A playground for emergent band topology, Kitaev magnetism, and magnetoelectricity

具有键依赖自旋轨道耦合的双轨道 $e_g$ 模型:涌现能带拓扑、Kitaev 磁性和磁电效应的游乐场

YuZheng Xie, Manoj Gupta, Arun Paramekanti, Tanusri Saha-Dasgupta

AI总结 基于镍二卤化物 Ni$X_2$ 的电子结构,提出低能双轨道 $e_g$ 模型,包含由配体原子自旋轨道耦合驱动的键依赖自旋轨道项,展示了非相互作用带中的拓扑带和更高阶拓扑态,以及半填充莫特绝缘体中的 Kitaev 交换相互作用和磁电效应。

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AI中文摘要

受镍二卤化物 Ni$X_2$($X$=Cl, Br, I)等化合物电子结构的启发,我们提出了一个低能双轨道 $e_g$ 模型,其特征是由配体 $X$ 上的原子自旋轨道耦合驱动的键依赖自旋轨道项。我们证明该模型拥有丰富的现象。在非相互作用带极限下,自旋轨道衍生的自旋依赖和自旋翻转跳跃项分别产生具有自旋陈数 $C_s=\pm 2, \pm 4$ 的拓扑带和具有分数角电荷的高阶拓扑态。在半填充莫特绝缘体极限下,我们恢复了一个具有键依赖 Kitaev 交换相互作用的自旋-$1$ 哈密顿量。我们利用基于对称性的视角和微观计算探索了该双轨道模型中的磁电效应,超越了单轨道情况的广义 Katsura-Nagaosa-Balatsky 理论。我们的工作可能与 Ni$X_2$ 及相关材料的掺杂、应变或压力研究相关。

英文摘要

Inspired by the electronic structure of compounds like nickel dihalides Ni$X_2$ ($X$=Cl, Br, I), we propose a low-energy two-orbital $e_g$ model featuring bond-dependent spin-orbit terms, driven by atomic spin-orbit coupling on the ligand $X$. We demonstrate that this model hosts a rich array of phenomena. In the non-interacting band limit, spin-orbit-derived spin-dependent and spin-flip hopping terms produce topological bands with spin-Chern numbers $C_s=\pm 2, \pm 4$, and higher order topological states with fractional corner charges, respectively. In the half-filled Mott insulator limit, we recover a spin-$1$ Hamiltonian with bond-dependent Kitaev exchange interactions. We explore the magnetoelectric effect in this two-orbital model using symmetry-based perspective and microscopic calculations, going beyond the generalized Katsura-Nagaosa-Balatsky theory for the single-orbital case. Our work may be relevant to study of doping, strain, or pressure on Ni$X_2$ and related materials.

2606.02713 2026-06-03 cond-mat.quant-gas cond-mat.stat-mech quant-ph

A mean-field description of strong-to-weak symmetry breaking in the monitored three-dimensional Bose-Hubbard model

受控三维Bose-Hubbard模型中强弱对称性破缺的平均场描述

Yicheng Tang, Pradip Kattel, J. H. Pixley

AI总结 通过Gutzwiller平均场框架模拟受控Bose-Hubbard模型,发现局域序参量在测量强度临界点附近表现出强弱对称性破缺,且与电荷锐化转变具有相同临界指数,表明两者可能源于同一临界点。

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AI中文摘要

强弱自发对称性破缺已成为受控和开放量子系统中一种新的有序形式,但其表征迄今主要依赖于非局域诊断。本文为受控玻色子晶格系统开发了Gutzwiller平均场框架,实现了三维空间中随机测量动力学的直接模拟。将该方法应用于具有局域密度测量和Lindblad耗散的受控Bose-Hubbard模型,我们通过轨迹平均的局域序参量识别出强弱对称性破缺。我们发现,该局域序参量在测量强度接近电荷锐化转变时变得临界,并表现出洛伦兹不变性,关联长度指数$\nu\simeq 1.2$与电荷锐化转变相当,表明这两种现象可能源于共同的临界点。我们的工作建立了强弱对称性破缺的局域表征,揭示了其与电荷锐化的联系,并为未来受控Bose-Hubbard模型的实验提供了具体预测。

英文摘要

Strong-to-weak spontaneous symmetry breaking has emerged as a novel form of ordering in monitored and open quantum systems, yet its characterization has so far primarily relied on nonlocal diagnostics. Here, we develop a Gutzwiller mean-field framework for monitored bosonic lattice systems, enabling the direct simulation of stochastic measurement dynamics in three spatial dimensions. Applying this approach to the monitored Bose-Hubbard model with local density measurements and Lindbladian dissipation, we identify strong-to-weak symmetry breaking through a trajectory-averaged local order parameter. We find that this local order parameter becomes critical near the same measurement strength as the charge-sharpening transition and exhibits Lorentz invariance with a correlation-length exponent, $ν\simeq 1.2$, comparable to that of the charge-sharpening transition, suggesting that the two phenomena may originate from a common underlying critical point. Our work establishes a local characterization of strong-to-weak symmetry breaking, reveals its connection to charge sharpening, and provides concrete predictions for future experiments on the monitored Bose-Hubbard model.

2606.02694 2026-06-03 cond-mat.supr-con cond-mat.mes-hall

Dynamical Josephson Effect Between a Singlet and a Triplet Superconductor

单态与三重态超导体之间的动力学约瑟夫森效应

Morten Amundsen, Niladri Banerjee, Igor Žutić

AI总结 通过建模由二维电子气分隔的自旋单态和自旋三重态超导体的约瑟夫森结,发现时变门电压可改变选择定则,产生静态下消失的振荡cosφ约瑟夫森分量,导致包含无耗散和耗散分量的电荷电流。

Comments 7 pages, 3 figures

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AI中文摘要

相位敏感的约瑟夫森效应长期以来一直是识别超导体中非常规配对对称性的核心。尽管决定约瑟夫森结(JJs)的选择定则通常由组成超导体的对称性决定,但我们证明这种范式在动态状态下被修改。通过建模一个由二维电子气分隔的自旋单态和自旋三重态超导体的JJ,我们展示了时变门电压定性地改变了潜在的选择定则。这种修改源于门控自旋轨道耦合。门电压的谐波调制产生了一个在静态极限下消失的振荡$\cos \phi$约瑟夫森分量。由此产生的电荷电流包含无耗散和耗散分量,后者在低温下被强烈抑制。这种动力学约瑟夫森效应可能改变JJs在量子比特、作为自旋三重态电流源以及作为邻近效应平台中的使用。

英文摘要

Phase-sensitive Josephson effect has long been central to identifying unconventional pairing symmetries in superconductors. Although the selection rules governing Josephson junctions (JJs) are generally determined by the symmetries of the constituent superconductors, we demonstrate that this paradigm is modified in the dynamic regime. By modeling a JJ where spin-singlet and spin-triplet superconductors are separated by a two-dimensional electron gas, we show that a time-dependent gate voltage qualitatively changes the underlying selection rules. This modification arises as a consequence of the gate-controlled spin-orbit coupling. A harmonic modulation of the gate voltage generates an oscillatory $\cos ϕ$ Josephson component which vanishes in the static limit. The resulting charge current contains both dissipationless and dissipative components, with the latter strongly suppressed at low temperatures. This dynamical Josephson effect could transform the use of JJs in qubits, as sources of spin-triplet currents, and as platforms for proximity effects.

2606.02682 2026-06-03 cond-mat.dis-nn math.PR

Neural Networks and Schramm-Loewner Evolutions

神经网络与Schramm-Loewner演化

Neilesh Shrotri, Vlad Margarint

AI总结 本文利用神经网络预测Schramm-Loewner演化(SLE)的自然参数κ,并验证了模型在不同κ值下的准确性。

Comments The version of record which also contains robustness analysis, Deep Learning experiments for the SLE traces, etc. is available at Neural Comput & Applic 38, 318 (2026). https://doi.org/10.1007/s00521-026-12058-3

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Journal ref
Neural Comput & Applic 38, 318 (2026)
AI中文摘要

在这篇手稿中,我们探索了应用神经网络来预测Schramm-Loewner演化(SLE$_\kappa$)理论中的自然参数$\kappa \geq 0$。SLE$_\kappa$是一族随机分形曲线,在统计力学和共形场论中具有重要意义。参数$\kappa \geq 0$在理论中扮演重要角色,因为平面统计物理中的一些模型已被证明具有SLE作为标度极限,而其他模型则被推测对于不同的$\kappa \geq 0$值具有该极限。此外,随着参数$\kappa$在$[0, \infty)$中变化,SLE曲线表现出三种不同的统计行为。利用神经网络强大的模式识别能力,本研究旨在开发一个能够以良好精度估计$\kappa$参数的预测模型。

英文摘要

In this manuscript, we explore the application of neural networks to predict the natural parameter $κ\geq 0$ of Schramm-Loewner Evolution (SLE$_κ$) theory. SLE$_κ$ is a family of random fractal curves that has significant implications in Statistical Mechanics and Conformal Field Theory. This parameter $κ\geq 0$ plays an important role in the theory as there are models of Planar Statistical Physics that are proven to have SLE as scaling limits as well as others that are conjectured to have this limit for various choices of the parameter $κ\geq 0$. In addition, there are three different statistical behaviors of the SLE curves as the parameter $κ$ changes in $[0, \infty).$ Leveraging the powerful pattern recognition capabilities of neural networks, this study aims to develop a predictive model that can estimate the $κ$ parameter with good accuracy.

2606.02622 2026-06-03 cond-mat.supr-con

On the Detection of Curl-Free Gauge Fields

关于无旋规范场的探测

Armen Gulian, Will Benston, Vahan Nikoghosyan

AI总结 本文通过非平衡过程中超导凝聚体的瞬态响应,证明无旋规范场在单连通系统中可被探测,并建立了基于时空动态闭合的探测原理。

Comments 2 figures plus online video (Ref. [20])

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AI中文摘要

在量子理论中,电磁规范场直接进入波函数的相位演化,甚至可以在相关电场和磁场为零的区域影响量子系统。Aharonov-Bohm效应表明,当相干量子系统沿双连通路径包围磁通时,此类规范场会产生可观测的后果。这导致了一种普遍观点,即无旋规范场在单连通系统中无法被探测,从而产生了一种拓扑盲性。在这里,我们证明这一结论并非根本性的。在非平衡过程中,集体量子系统可以在不包围静态几何中的磁通的情况下,对无旋规范场产生瞬态响应。以超导凝聚体为例,我们证明宏观波函数的演化相位会产生超电流和电压脉冲,其时间积分正比于矢势的开路径线积分。与传统的Aharonov-Bohm效应相比,所产生的响应不受磁通量子的模限制,并且可能大大超过与静态双连通几何相关的尺度。该机制可解释为规范轮廓在时空中的动态闭合,并得到规范不变论证、含时Ginzburg-Landau理论建模和数值模拟的支持。这些结果为探测无旋规范场建立了一般原理,并为探测量子物质及其他领域中隐藏的规范结构提出了新方法。

英文摘要

In quantum theory, electromagnetic gauge fields enter directly into the phase evolution of the wavefunction and can even influence quantum systems in regions where the associated electric and magnetic fields vanish. The Aharonov-Bohm effect demonstrates that such gauge fields produce observable consequences when a coherent quantum system encloses magnetic flux along a doubly connected path. This has led to the widespread view that curl-free gauge fields are undetectable in simply connected systems, giving rise to a form of topological blindness. Here we show that this conclusion is not fundamental. During nonequilibrium processes, collective quantum systems can develop transient responses to curl-free gauge fields without enclosing magnetic flux in a static geometry. Using superconducting condensates as a concrete example, we demonstrate that the evolving phase of the macroscopic wavefunction generates supercurrents and voltage pulses whose time integral is proportional to the open-path line integral of the vector potential. In contrast to the conventional Aharonov-Bohm effect, the resulting response is not restricted modulo the flux quantum and may greatly exceed the scale associated with static doubly connected geometries. The mechanism can be interpreted as a dynamical closure of the gauge contour in spacetime and is supported by gauge-invariant arguments, time-dependent Ginzburg-Landau theory modeling, and numerical simulations. These results establish a general principle for detecting curl-free gauge fields and suggest new approaches for probing hidden gauge structures in quantum matter and beyond.