超导性
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显示 2025年09月05日， 星期五 新的列表
- [1] arXiv:2509.03683 [中文pdf, pdf, html, 其他]
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标题： 注意力是解决手性超导性的全部所需标题： Attention is all you need to solve chiral superconductivity评论： 15页，9图，1表主题： 超导性 (cond-mat.supr-con)
最近在神经量子态方面的进展表明，量子粒子之间的关联可以通过{\it attention}有效捕捉——这是现代神经架构的基础，使神经网络能够学习物体之间的关系。 在本工作中，我们表明一种通用的自注意力费米神经网络可以通过能量最小化在吸引费米气体中找到手征$p_x \pm i p_y$超导性，{\it 不带任何关于配对的先验知识或偏见}。 超导态通过测量各种物理可观测量从优化的波函数中识别出来：成对结合能、基态的总角动量以及两体约化密度矩阵中的非对角长程序。 我们的工作为在强关联量子材料中发现非常规和拓扑超导性提供了道路。
Recent advances on neural quantum states have shown that correlations between quantum particles can be efficiently captured by {\it attention} -- a foundation of modern neural architectures that enables neural networks to learn the relation between objects. In this work, we show that a general-purpose self-attention Fermi neural network is able to find chiral $p_x \pm i p_y$ superconductivity in an attractive Fermi gas by energy minimization, {\it without prior knowledge or bias towards pairing}. The superconducting state is identified from the optimized wavefunction by measuring various physical observables: the pair binding energy, the total angular momentum of the ground state, and off-diagonal long-range order in the two-body reduced density matrix. Our work paves the way for AI-driven discovery of unconventional and topological superconductivity in strongly correlated quantum materials.
- [2] arXiv:2509.03774 [中文pdf, pdf, html, 其他]
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标题： 用常规超导体使近邻磁体化标题： Proximitizing altermagnets with conventional superconductors主题： 超导性 (cond-mat.supr-con) ; 材料科学 (cond-mat.mtrl-sci) ; 强关联电子 (cond-mat.str-el)
最近的理论工作强调了超导交替磁体的独特性质，包括丰富的拓扑非平凡相以及它们在自旋电子学应用中的潜力。 鉴于尚未发现本征超导交替磁体，我们在此研究了由常规s波超导体的邻近效应诱导超导序的可能性。 通过对称性分析和微观模型，我们发现如果界面处存在弱的Rashba自旋轨道耦合，确实可以在薄的交替磁体薄膜中诱导出有趣的超导相。 令人惊讶的是，所产生的超导体通常是节点型的，具有混合的单重态/三重态序参量，并且对于应用来说，能够产生自旋极化的持续电流。 我们提出了一组具有低晶格失配度的候选异质结构，适合实验探测这些效应。
Recent theoretical work highlighted unique properties of superconducting altermagnets, including the wealth of topologically non-trivial phases as well as their potential uses in spintronic applications. Given that no intrinsically superconducting altermagnets have yet been discovered, we study here the possibility of superconducting order induced by proximity effect from a conventional s-wave superconductor. Through symmetry analysis and microscopic modeling we find that interesting superconducting phases can indeed be proximity-induced in a thin altermagnetic film provided that weak Rashba spin-orbit coupling is present at the interface. Surprisingly, the resulting superconductor is generically nodal with a mixed singlet/triplet order parameter and, importantly for applications, capable of generating spin-polarized persistent current. We propose a set of candidate heterostructures with low lattice mismatch suitable to probe these effects experimentally.
- [3] arXiv:2509.03801 [中文pdf, pdf, html, 其他]
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标题： 可调控的约瑟夫森二极管效应，$0$-$π$转变和开关效应在超导体/二维外尔节线半金属/超导体结中标题： Controllable Josephson diode effect, $0$-$π$ transition and switch effect in the superconductor/two-dimensional Weyl nodal line semimetal/superconductor junctions评论： 10页，7图期刊参考： 物理评论B 112 (2025) 054509主题： 超导性 (cond-mat.supr-con)
我们使用格林函数方法研究超导体/二维外尔节线半金属/超导体结中的约瑟夫森效应。 当半导体中同时存在Rashba自旋-轨道耦合和外部磁场时，保护超电流对称性的对称性可能被破坏，从而实现具有超电流非对称性的约瑟夫森二极管效应。 通过实验可实现的磁场和Rashba自旋-轨道耦合值，可以实现超过$40\%$的高效率。 二极管效率可以通过磁场的方向和大小以及自旋-轨道耦合的强度轻松控制。 当没有自旋-轨道耦合或没有外部场时，约瑟夫森二极管效应消失，但电流-相位差关系仍然表现出对场或耦合的强依赖性。 如果旋转场的方向或改变场的大小和耦合的强度，可以在结中形成可调的$0$-$\pi$转变和超电流的开关效应。 获得的约瑟夫森二极管效应、$0$-$\pi$转变和超电流的开关效应有助于基于节线半金属的量子器件的设计。
We study the Josephson effects in the superconductor/two-dimensional Weyl nodal line semimetal/superconductor junctions using the Green's function method. When the Rashba spin-orbit coupling and an external magnetic field coexist in the semimetal, the symmetries protecting the reciprocity of supercurrent can be broken and the Josephson diode effect with the nonreciprocity of supercurrent can be realized. A high efficiency exceeding $40\%$ can be achieved with the experimentally accessible values of the magnetic field and the Rashba spin-orbit coupling. The diode efficiency can be easily controlled by the direction and magnitude of the field and the strength of the spin-orbit coupling. When the spin-orbit coupling is absent or the external field is absent, the Josephson diode effect vanishes but the current-phase difference relations still show strong dependence on the field or the coupling. The tunable $0$-$\pi$ transition and the switch effect of supercurrent in the junctions can be formed if the direction of the field is rotated or the magnitude of the field and the strength of the coupling are changed. The obtained Josephson diode effect, the $0$-$\pi$ transition and the switch effect of supercurrent are helpful in the design of the quantum devices based on nodal line semimetals.
- [4] arXiv:2509.03907 [中文pdf, pdf, html, 其他]
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标题： 单层过渡金属二硫属化物中的非常规超导性标题： Unconventional superconductivity in monolayer transition metal dichalcogenides评论： 15页，14图主题： 超导性 (cond-mat.supr-con) ; 强关联电子 (cond-mat.str-el)
在具有Ising自旋轨道耦合的单层过渡金属二硫属化合物超导体中，多种实验观察结果表明存在非常规的超导配对机制。这些实验包括扫描隧道显微镜实验中观察到的Leggett模和节点状超导能隙、与Pauli极限相比更大的面内上临界场，以及磁阻测量中观察到的两倍能隙各向异性。在这里，我们提出一种由自旋和电荷涨落介导的超导配对机制，并确定与单层TaS$_2$相关的主要超导不稳定性。然后，我们探讨了额外电子-声子配对贡献的影响，并将我们的结果与最近的实验发现进行比较。特别是，我们的理论稳定了一个具有类似节点态密度的超导基态，这与扫描隧道显微镜实验一致。由于超导态中Ising自旋轨道耦合和偶奇宇称混合的结合，该理论获得了较大的面内上临界场。此外，我们发现面内磁场会分裂超导基态的简并度， resulting 的两倍对称超导序参量可以解释磁阻实验中观察到的能隙各向异性。总体而言，所提出的理论配对模型可以调和各种实验观察结果，并且与其它二硫属化合物超导体如单层NbSe$_2$的观察结果保持一致。
A variety of experimental observations in monolayer transition metal dichalcogenide superconductors with Ising spin-orbit coupling suggest the presence of an unconventional superconducting pairing mechanism. Some of these experiments include observation of Leggett modes and a nodal superconducting gap in STM experiments, a large in-plane upper critical field compared to the Pauli limit, and the observation of a two-fold gap anisotropy in magnetoresistance measurements. Here, we propose a superconducting pairing mechanism mediated by spin and charge fluctuations and identify the dominant superconducting instability relevant to monolayer TaS$_2$. We then explore the effect of an additional electron-phonon pairing contribution, and compare our results with recent experimental findings. In particular, our theory stabilizes a superconducting ground state with nodal-like density of states that agrees with STM experiments. The theory obtains a large in-plane upper critical field due to a combination of Ising spin-orbit coupling and even-odd parity mixing in the superconducting state. Further, we find that an in-plane magnetic field splits the degeneracy of the superconducting ground state, and the resulting two-fold symmetric superconducting order parameter could explain the gap anisotropy observed in magnetoresistance experiments. Overall, the proposed theoretical pairing model can reconcile diverse experimental observations and remains consistent with observations on other dichalcogenide superconductors such as monolayer NbSe$_2$.
- [5] arXiv:2509.03915 [中文pdf, pdf, html, 其他]
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标题： 超导透镜和AA堆叠双层石墨烯中的约瑟夫森效应标题： Superconducting lens and Josephson effect in AA-stacked bilayer graphene期刊参考： 物理评论B 111, 165411 (2025)主题： 超导性 (cond-mat.supr-con)
我们研究了AA堆叠双层石墨烯中的超导输运现象，包括透镜效应和超电流，其特征是具有两个位移的狄拉克锥的线性无能隙带。 我们的研究结果表明，交叉安德烈夫反射和约瑟夫森电流仅在同锥过程中发生，而异锥散射则被严格禁止。 正常/超导/正常结可以作为上下锥的超导透镜。 根据锥指数，通过调整栅极电压，传输的电子和空穴可以被聚焦、准直或发散。 在超导/正常/超导结中，由于层间耦合，两个锥的临界电流随结宽表现出不同的振荡周期，导致总临界电流出现不规则振荡。 此外，交换场下临界电流的振荡在两个锥之间保持一个四分之一周期的稳定相位差。 因此，在这种约瑟夫森结中实现了依赖于锥的0-\pi 转变。
We study the superconducting transport phenomena, involving lensing effect and supercurrent in AA-stacked bilayer graphene, which is characterized by a linear gapless band with two shifted Dirac cones. Our findings indicate that cross Andreev reflection and Josephson current occur exclusively within the intracone process, while intercone scatterings are strictly prohibited. The normal/superconductor/normal junction can act as a superconducting lens for the upper and lower cones. Depending on cone index, the transmitted electrons and holes can be focused, collimated or diverged by adjusting the gate voltages. In superconductor/normal/superconductor junction, due to interlayer coupling, the critical currents of the two cones exhibit distinct oscillation periods with junction width, leading to an irregular oscillation of the total critical current. Furthermore, the oscillations of critical currents with exchange field maintain a stable phase difference of one quarter period between the two cones. Consequently, a cone-dependent 0-\pi transition is achieved in this Josephson junction.
- [6] arXiv:2509.03936 [中文pdf, pdf, html, 其他]
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标题： 无序超导体在窄带和宽带极限下的二维相干光谱学标题： Two-dimensional coherent spectroscopy of disordered superconductors in the narrow-band and broad-band limits评论： 22页，14图主题： 超导性 (cond-mat.supr-con)
我们理论分析了无序超导体在两个极限下的二维相干光谱(2DCS)信号：一个是窄带极限，使用正弦脉冲波，另一个是宽带极限，使用δ函数脉冲。 虽然窄带极限下的2DCS信号与三阶非线性极化率$\chi^{(3)}(3\Omega; \Omega, \Omega, \Omega)$（三次谐波产生）和$\chi^{(3)}(\Omega; \Omega, \Omega, -\Omega)$（交流Kerr效应）有关，但我们发现，在宽带极限下，二维频率空间中对角线和水平线上信号与另一种非线性极化率$\chi^{(3)}(\Omega; \Omega, 0, 0)$（直流Kerr效应）有关。 我们基于BCS平均场理论和杂质的自洽玻恩近似，对超导体的格点模型中的这些极化率进行了数值评估。 窄带和宽带极限下的2DCS信号分别在超导能隙频率处表现出阈值和共振行为，其物理起源结合准粒子和希格斯模激发进行了讨论。
We theoretically analyze two-dimensional coherent spectroscopy (2DCS) signals for disordered superconductors in two limits: One is the narrow-band limit with sinusoidal pulse waves, and the other is the broad-band limit with delta-function pulses. While the 2DCS signal in the narrow-band limit is related to the third-order nonlinear susceptibilities $\chi^{(3)}(3\Omega; \Omega, \Omega, \Omega)$ (third harmonic generation) and $\chi^{(3)}(\Omega; \Omega, \Omega, -\Omega)$ (ac Kerr effect), we find that in the broad-band limit the signal along the diagonal and horizontal lines in the two-dimensional frequency space is related to another nonlinear susceptibility $\chi^{(3)}(\Omega; \Omega, 0, 0)$ (dc Kerr effect). We numerically evaluate those susceptibilities for a lattice model of superconductors based on the BCS mean-field theory and self-consistent Born approximation for impurities. The 2DCS signals in the narrow-band and broad-band limits show threshold and resonance behaviors at the superconducting-gap frequency, respectively, whose physical origin is discussed in light of quasiparticle and Higgs-mode excitations.
- [7] arXiv:2509.03949 [中文pdf, pdf, html, 其他]
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标题： 可调谐的马约拉纳角态由垂直约瑟夫森结中的超导相位偏置驱动标题： Tunable Majorana corner states driven by superconducting phase bias in a vertical Josephson junction评论： 11页，7图主题： 超导性 (cond-mat.supr-con)
实现和操控马约拉纳零模是实现拓扑量子计算的关键步骤。 在本文中，我们展示了在超导-绝缘体-超导垂直约瑟夫森结中存在马约拉纳角态。 这些马约拉纳角态的位置可以通过超导相位偏置精确且容易地控制，这通过数值和边缘态理论分析得到了确认。 此外，我们提出了一种在三个圆形垂直约瑟夫森结系统中实现马约拉纳角态拓扑编织的协议。 我们的研究通过提供对马约拉纳角态高效精确操控的新见解，推动了拓扑量子计算领域的发展。
The realization and manipulation of Majorana zero modes is a key step in achieving topological quantum computation. In this paper, we demonstrate the existence of Majorana corner states in a superconductor-insulators-superconductor vertical Josephson junction. The position of these Majorana corner states can be precisely and easily controlled by the superconducting phase bias, which be confirmed through both numerical and edge state theoretical analysis. In addition, we propose a protocol for achieving topological braiding of the Majorana corner states in a system of three circular vertical Josephson junctions. Our findings advance the field of topological quantum computation by providing new insights into the efficient and precise manipulation of Majorana corner states.
- [8] arXiv:2509.03984 [中文pdf, pdf, html, 其他]
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标题： 基于双磁杂质的约瑟夫森二极管的设计标题： Design of a Josephson diode based on double magnetic impurities评论： 11页，6图期刊参考： 物理评论B 111, 054515 (2025)主题： 超导性 (cond-mat.supr-con)
我们理论上提出了一种基于双磁杂质的通用超导二极管器件，这些磁杂质与约瑟夫森结的连接区域耦合。 正向和反向电流流过结时会产生相反的磁场，使侧边磁杂质的磁矩翻转到相反方向，从而两个杂质会对相反电流产生不同的影响。 这导致正向和反向临界电流不相等的现象，称为超导二极管效应（SDE）。 使用非平衡格林函数方法（NEGF），我们得到了方向依赖的临界电流。 我们确认了SDE的存在，并展示了超导二极管效率对一系列参数的依赖性，包括磁矩的大小、方向和位置。 此外，我们系统地分析了系统中非互易性的对称关系。 我们的方案通过避免对外部磁场、库珀对动量和自旋轨道耦合的需求，具有很高的实用性。 我们的方法为非互易电子电路的发展开辟了新可能性，并为超导器件的进步提供了另一种视角。
We theoretically propose a universal superconducting diode device based on double magnetic impurities which are coupled to the connection region of the Josephson junction. The positive and negative currents flowing across the junction can generate opposite magnetic fields, flipping the magnetic moment of the side magnetic impurity to the opposite directions, and in turn, the two impurities will have different impacts on the opposite currents. This results in the phenomenon that the positive and negative critical currents are unequal, referred to as the superconducting diode effect (SDE). Using the nonequilibrium Green's function method (NEGF), we obtain the direction-dependent critical currents. We confirm the emergency of the SDE and demonstrate the dependence of the superconducting diode efficiency on a range of parameters including the magnitude, the direction, and the position of the magnetic moment. Besides, we systematically analyze the symmetry relations of the nonreciprocity in our system. Our proposal has high practicability by avoiding the demand on the external magnetic field, the Cooper pair momentum, and the spin-orbit coupling. Our approach opens up new possibilities for the development of nonreciprocal electronic circuits and provides an alternate perspective on the advancement of superconducting devices.
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- [9] arXiv:2509.03583 (交叉列表自 cond-mat.mes-hall) [中文pdf, pdf, html, 其他]
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标题： 多莫尔超晶格扭曲三重层石墨烯中的魔幻连续体标题： Magic continuum in multi-moiré twisted trilayer grapheneLi-Qiao Xia, Aviram Uri, Jiaojie Yan, Aaron Sharpe, Filippo Gaggioli, Nicole S. Ticea, Julian May-Mann, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Trithep Devakul, Jurgen H. Smet, Pablo Jarillo-Herrero主题： 中尺度与纳米尺度物理 (cond-mat.mes-hall) ; 强关联电子 (cond-mat.str-el) ; 超导性 (cond-mat.supr-con)
莫尔晶格为探索电子关联与能带拓扑之间的相互作用提供了一个高度可调的平台。引入第二个莫尔图案扩展了这一范式：两个莫尔图案之间的干涉产生了一种超莫尔调制，开辟了一条进一步定制电子性质的途径。扭曲的三层石墨烯通常代表了这样的系统：由于相邻石墨烯层之间的相对扭转，会产生两种不同的莫尔图案。在这里，我们报告了在一系列扭曲的三层石墨烯器件中观察到的相关现象，这些器件的扭转角度位于扭转角度参数空间中的两条连续线上。根据晶格弛豫的程度，扭曲的三层石墨烯可分为两类：由具有局部共格莫尔序的周期性区域组成的莫尔多晶体，以及具有平滑变化的局部莫尔构型的莫尔准晶体。在螺旋扭曲的莫尔多晶体中，我们观察到了异常霍尔效应，这与来自具有破坏$xy$反演对称性的区域的拓扑能带一致。相反，超导性在我们的莫尔准晶体中普遍存在。其中一部分系统表现出空间调制超导性的特征，我们将其归因于超莫尔结构。我们的发现揭示了扭曲三层石墨烯中观察到的相关相的组织原则，强调了超莫尔调制和晶格弛豫的关键作用，并提出了一个更广泛的框架，在该框架中，魔法条件不是作为孤立点出现，而是在复杂莫尔材料的多维扭转角度空间中的扩展流形。
Moir\'e lattices provide a highly tunable platform for exploring the interplay between electronic correlations and band topology. Introducing a second moir\'e pattern extends this paradigm: interference between the two moir\'e patterns produces a supermoir\'e modulation, opening a route to further tailor electronic properties. Twisted trilayer graphene generally exemplifies such a system: two distinct moir\'e patterns arise from the relative twists between adjacent graphene layers. Here, we report the observation of correlated phenomena across a wide range of twisted trilayer graphene devices whose twist angles lie along two continuous lines in the twist-angle parameter space. Depending on the degree of lattice relaxation, twisted trilayer graphene falls into two classes: moir\'e polycrystals, composed of periodic domains with locally commensurate moir\'e order, and moir\'e quasicrystals, characterized by smoothly varying local moir\'e configurations. In helically twisted moir\'e polycrystals, we observe an anomalous Hall effect, consistent with topological bands arising from domains with broken $xy$-inversion symmetry. In contrast, superconductivity appears generically in our moir\'e quasicrystals. A subset of these systems exhibits signatures of spatially modulated superconductivity, which we attribute to the supermoir\'e structure. Our findings uncover the organizing principles of the observed correlated phases in twisted trilayer graphene, highlight the critical roles of the supermoir\'e modulation and lattice relaxation, and suggest a broader framework in which magic conditions arise not as isolated points but as extended manifolds within the multi-dimensional twist-angle space of complex moir\'e materials.
- [10] arXiv:2509.03750 (交叉列表自 cond-mat.str-el) [中文pdf, pdf, html, 其他]
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标题： 无限层镍酸镧LaNiO$_2$的晶格动力学标题： Lattice dynamics of the infinite-layer nickelate LaNiO$_2$Shohei Hayashida, Vignesh Sundaramurthy, Wenfeng Wu, Pascal Puphal, Thomas Keller, Björn Fåk, Masahiko Isobe, Bernhard Keimer, Karsten Held, Liang Si, Matthias Hepting主题： 强关联电子 (cond-mat.str-el) ; 超导性 (cond-mat.supr-con)
无限层（IL）镍酸盐迅速成为一类新的超导体。 然而，由于其拓扑合成的技术挑战，它们迄今为止主要以薄膜或多晶粉末样品的形式实现，限制了对诸如晶格动力学等基本物理性质的全面研究。 在此，我们对由大量共取向的块体晶体组成的IL镍酸盐LaNiO$_2$样品进行了飞行时间非弹性中子散射研究。 我们观察到几个色散声子分支，这与基于密度泛函微扰理论的晶格动力学计算结果良好一致。 此外，我们将选定的LaNiO$_2$声子模式特性与同结构的铜氧化物超导体进行比较。 我们的发现为未来实验和理论研究提供了参考点，旨在理解IL镍酸盐中晶格动力学与电子性质之间的相互作用。
Infinite-layer (IL) nickelates have rapidly emerged as a new class of superconductors. However, due to the technical challenges of their topotactic synthesis, they have so far been realized primarily as thin films or polycrystalline powder samples, limiting comprehensive investigations of fundamental physical properties such as the lattice dynamics. Here, we present a time-of-flight inelastic neutron scattering study on a sample composed of a large number of co-aligned bulk crystals of the IL nickelate LaNiO$_2$. We observe several dispersive phonon branches, which are in good agreement with lattice dynamical calculations based on density-functional perturbation theory. In addition, we compare the characteristics of selected LaNiO$_2$ phonon modes to those of isostructural cuprate superconductors. Our findings provide a reference point for future experimental and theoretical efforts aimed at understanding the interplay between lattice dynamics and electronic properties in IL nickelates.
- [11] arXiv:2509.04002 (交叉列表自 cond-mat.mes-hall) [中文pdf, pdf, html, 其他]
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标题： 量子点-马约拉纳零能模耦合系统的相变标题： Phase transitions in quantum dot-Majorana zero mode coupling systems评论： 18页，7图期刊参考： 科学论文物理核心 8，031 (2025)主题： 中尺度与纳米尺度物理 (cond-mat.mes-hall) ; 超导性 (cond-mat.supr-con)
量子点(QD)的磁双态基态(GS)可以通过与超导体耦合变为自旋单态基态。 类似地，这里我们研究量子点-马约拉纳零模(MZM)耦合系统中的基态相变：基态的行为随着量子点内能级和量子点-MZM耦合强度而发生相变。 获得了基态的相图，包括存在和不存在泽曼项的情况。 除了相变，我们还研究了自旋特性和态密度的变化。 通过平均场图像理解相变的特性。 我们的研究不仅作为量子点-超导体相变的类比，还对与MZM相关的实验提供了其他解释。
The magnetic doublet ground state (GS) of a quantum dot (QD) could be changed to a spin-singlet GS by coupling to a superconductor. In analogy, here we study the GS phase transitions in QD-Majorana zero mode (MZM) coupling systems: GS behaves phase transition versus intra-dot energy level and QD-MZM coupling strength. The phase diagrams of GS are obtained, for cases with and without Zeeman term. Along with the phase transition, we also study the change of spin feature and density of states. The properties of the phase transition are understood via a mean-field picture. Our study not only serves as an analogue to QD-superconductor phase transitions, but also gives alternative explanations on MZM-relevant experiments.
- [12] arXiv:2509.04003 (交叉列表自 cond-mat.mes-hall) [中文pdf, pdf, html, 其他]
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标题： 铁磁/超导结中交叉安德烈夫反射和自旋谷开关的电控标题： Electrical control of crossed Andreev reflection and spin-valley switch in antiferromagnet/superconductor junctions评论： 9页，8图期刊参考： 物理评论B 104, 045418 (2021)主题： 中尺度与纳米尺度物理 (cond-mat.mes-hall) ; 超导性 (cond-mat.supr-con)
我们研究了在通用弯曲蜂窝系统（如硅烯、锗烯和锡烯）中，通过反铁磁/超导（AF/S）和反铁磁/超导/反铁磁（AF/S/AF）结的亚能隙输运，该过程由电场控制。在存在电场和反铁磁交换场的情况下，由于自旋轨道耦合，蜂窝系统中可以实现自旋-谷极化的半金属相，这为产生纯交叉安德烈夫反射（CAR）提供了机会。发现纯CAR可以在宽范围的电场下产生，而无需局部安德烈夫反射（AR）和弹性库伦隧穿（EC）。通过调整电场，可以在纯CAR和纯EC之间实现自旋-谷开关效应。AR过程和CAR过程的特性强烈依赖于自旋-谷极化状态。我们的结果表明，该器件可以实现对CAR过程和自旋-谷开关的电测量。
We study the subgap transport through the antiferromagnet/superconductor (AF/S) and antiferromagnet/superconductor/antiferromagnet (AF/S/AF) junctions controlled by electric field in a generic buckled honeycomb system, such as silicene, germanene, and stanene. In the present of electric field and antiferromagnetic exchange field, the spin-valley polarized half metallic phase can be achieved in the honeycomb system due to the spin-orbit coupling, which affords an opportunity to generate the pure crossed Andreev reflection (CAR). It is found that the pure CAR can be generated without local Andreev reflection (AR) and elastic cotunneling (EC) over a wide range of electric field. A spin-valley switch effect can be realized between the pure CAR and the pure EC by adjusting the electric field. The properties of AR process and CAR process strongly depend on the spin-valley polarized states. Our results suggest that the device can implement an electrical measurement of the CAR process and spin-valley switch.
交叉提交 (展示 4 之 4 条目 )
- [13] arXiv:2310.20017 (替换) [中文pdf, pdf, 其他]
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标题： II型超导体中超导性的空间分辨标题： Spatially resolving superconductivity in type-II superconductorsDonald M. Evans, Michele Conroy, Lukas Puntigam, Dorina Croitori, Lilian Prodan, Marin Alexe, James O. Douglas, Baptiste Gault, Vladimir Tsurkan主题： 超导性 (cond-mat.supr-con) ; 材料科学 (cond-mat.mtrl-sci) ; 强关联电子 (cond-mat.str-el)
超导性通过宏观零电阻态的出现来识别，通常通过在有限电流下四探针电压消失来推断。这种推断假设了空间均匀的导电性——例如，在电流引线和采样有限电势梯度的电压电极之间至少存在一条连续的超导路径——如果驱动电流绕过电极或狭窄的细丝短路电流接触，这种推断可能会失败。在这里，我们介绍了一种方法，通过使用低温导电原子力显微镜（cAFM）对局部直流变化进行空间分辨测量，来测试这些假设。使用Fe(Se,Te)作为模型系统，我们发现尽管体测量与均匀超导态一致，但该材料表现出异质的导电景观：微米尺度的超导区域与相对绝缘的区域共存。我们进一步表明，cAFM在20 K（> TC）时解析出导电性波动，这些波动在重复扫描中变化，符合BCS-BEC交叉区域中短暂存在的预形成库珀对的预期。这些结果确立了cAFM作为一种实用工具，用于验证四探针输运背后的假设，并强调了在宏观响应可能掩盖纳米尺度不均匀性的材料中进行直接空间探测的必要性。准确识别宏观特性对于由其宏观特性定义的材料类别如超导体至关重要。
Superconductivity is identified by the emergence of a macroscopic zero-resistance state, typically inferred from a vanishing four-probe voltage at finite current. That inference assumes spatially uniform conduction-e.g., at least one continuous superconducting path between the current leads and voltage electrodes that sample a finite potential gradient-and can fail if the drive current bypasses the electrodes or if narrow filaments short the current contacts. Here we introduce a methodology to test these assumptions in superconductors, by using spatially resolved measurements of local variations in dc using cryogenic conductive atomic-force microscopy (cAFM). Using Fe(Se,Te) as a model system, we find that despite bulk measurements consistent with a homogeneous superconducting state, the material exhibits a heterogeneous conducting landscape: micrometre-scale superconducting regions coexist with relatively insulating areas. We further show that cAFM resolves conductance fluctuations at 20 K (> TC) that vary between repeated scans, consistent with expectations for short-lived, pre-formed Cooper pairs in the BCS-BEC crossover regime. These results establish cAFM as a practical tool to validate assumptions underlying four-probe transport and underscore the need for direct spatial probes in materials whose macroscopic response can conceal nanoscale inhomogeneity. Accurate identification of macroscopic properties is critical for materials classes like superconductors that are defined by their macroscopic properties.
- [14] arXiv:2508.17707 (替换) [中文pdf, pdf, 其他]
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标题： 考虑从磁测量中得到的临界电流密度的HTS颗粒尺寸分布标题： Accounting the size distribution of HTS granules for the critical current density from magnetic measurements评论： 7页，3图期刊参考： 超导性：基础与应用研究 2(7) (2025) 52-58主题： 超导性 (cond-mat.supr-con) ; 材料科学 (cond-mat.mtrl-sci)
从磁滞回线确定临界电流密度被广泛用于表征和比较超导样品。 带材和单晶的磁滞回线取决于临界电流密度和样品尺寸。 后者决定了超导电流循环的尺度。 然而，在通过固相合成或溶胶-凝胶法制备的多晶高温超导体中，磁化由单个晶粒中超导电流的循环决定。 本文讨论了晶粒尺寸分布对电流循环有效尺度的影响。 对数正态分布和威布尔分布都被认为是晶粒尺寸的可能分布。 计算晶内电流密度的有效尺寸已被证明明显大于平均晶粒尺寸。
The determination of the critical current density from magnetic hysteresis loops is widely used to characterize and compare superconducting samples. Magnetic hysteresis loops for tapes and single crystals depend on both the critical current density and sample size. The latter sets the scale of supercurrent circulation. However, in polycrystalline high-temperature superconductors prepared by solid-phase synthesis or by sol-gel method, the magnetization is determined by the circulation of supercurrents in individual grains. The paper discusses the effect of the grain size distribution on the effective scale of current circulation. Log-normal and Weibull distributions are both considered as possible for grain sizes. The effective size for calculating the intragrain current density has been shown to be significantly larger than the average grain size.
- [15] arXiv:2411.18542 (替换) [中文pdf, pdf, html, 其他]
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标题： 费米面和高掺杂 Sr$_{2}$IrO$_{4}$中的赝能隙标题： Fermi surface and pseudogap in highly doped Sr$_{2}$IrO$_{4}$Y. Alexanian, A. de la Torre, S. McKweon Walker, M. Straub, G. Gatti, A. Hunter, S. Mandloi, E. Cappelli, S. Riccò, F. Y. Bruno, M. Radovic, N. C. Plumb, M. Shi, J. Osiecki, C. Polley, T. K. Kim, P. Dudin, M. Hoesch, R. S. Perry, A. Tamai, F. Baumberger评论： 9页，4图。补充信息：3页，3图主题： 强关联电子 (cond-mat.str-el) ; 超导性 (cond-mat.supr-con)
费米面在体电子掺杂的Sr$_{2}$IrO$_{4}$中的命运仍然难以捉摸，其赝隙相的起源和扩展也是如此。 在这里，我们使用高分辨率角分辨光电子能谱（ARPES）研究Sr$_{2-x}$La$_{x}$IrO$_{4}$的电子结构，直至$x=0.2$，这比以前的工作高两倍。 我们发现反节点赝隙持续到最高的掺杂水平，并因此超越了在$x^{*}\simeq 0.16$以上最近观察到的霍尔载流子密度急剧增加至$\simeq 1+x$[Y.-T. Hsu 等，Nature Physics 20, 1593 (2024)]。 这表明掺杂铱氧化物中存在一种独特的物质相，在这种相中，大的霍尔密度与各向异性的赝隙共存，将费米面分割成不相连的弧。 赝隙的温度边界为$T^{*}\simeq 200$K 对于$x=0.2$，与铜氧化物和铜氧化物及铱氧化物中短程反铁磁关联的能量尺度相当。
The fate of the Fermi surface in bulk electron-doped Sr$_{2}$IrO$_{4}$ remains elusive, as does the origin and extension of its pseudogap phase. Here, we use high-resolution angle-resolved photoelectron spectroscopy (ARPES) to investigate the electronic structure of Sr$_{2-x}$La$_{x}$IrO$_{4}$ up to $x=0.2$, a factor of two higher than in previous work. We find that the antinodal pseudogap persists up to the highest doping level, and thus beyond the sharp increase in Hall carrier density to $\simeq 1+x$ recently observed above $x^{*}\simeq 0.16$ [Y.-T. Hsu et al., Nature Physics 20, 1593 (2024)]. This suggests that doped iridates host a unique phase of matter in which a large Hall density coexists with an anisotropic pseudogap, breaking up the Fermi surface into disconnected arcs. The temperature boundary of the pseudogap is $T^{*}\simeq 200$ K for $x=0.2$, comparable to cuprates and to the energy scale of short range antiferromagnetic correlations in cuprates and iridates.
- [16] arXiv:2503.06018 (替换) [中文pdf, pdf, html, 其他]
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标题： 关联电子格点极化子系统的赝隙能带结构的演化标题： Evolution of the pseudogap band structure in a system of electron-correlated lattice polarons评论： 12页，11图主题： 强关联电子 (cond-mat.str-el) ; 超导性 (cond-mat.supr-con)
晶格振动在强关联电子系统中赝隙态形成中的作用的演变已被研究，涉及电子-声子耦合参数和掺杂电荷载流子浓度的变化。 我们应用广义紧束缚方法的极化子版本来分析一个现实的多带二维模型的能带结构，该模型包含了霍尔斯坦型和皮尔斯型的电子-晶格贡献。 已经证明，极化子效应的出现始于谱函数强度的调制。 然而，在相图的特定区域内，电子能带结构和赝隙态会发生显著变化。 这是由于相干极化子激发在费米能级附近产生了部分平坦的能带。 这一过程导致费米面的拓扑结构发生变化，并在态密度中出现相应的特征。
The evolution of the role of lattice vibrations in the formation of the pseudogap state in strongly correlated electron systems has been investigated concerning changes in the electron-phonon coupling parameters and the concentration of doped charge carriers. We apply the polaronic version of the generalized tight-binding method to analyze the band structure of a realistic multiband two-dimensional model that incorporates the electron-lattice contributions of both Holstein and Peierls types. It has been demonstrated that the emergence of polaronic effects begins with the modulation of spectral function intensity. However, within a specific region of the phase diagram, a significant transformation of the electron band structure and pseudogap state occurs. It results from coherent polaron excitations that create a partially flat band near the Fermi level. This process leads to a change in the topology of the Fermi surface and the emergence of corresponding features in the density of states.