超导三维收缩结构中几何诱导的电流去拥挤效应
Geometry-induced current decrowding in superconducting 3D constrictions
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中文总结 AI 辅助
本研究通过三维几何工程实现超导收缩结构中的电流去拥挤，利用含时金兹堡-朗道方程建模揭示磁场可调临界电流及涡旋三维分裂机制，为纳米超导器件设计提供新范式。
中文摘要 AI 辅助
电流拥挤是纳米尺度器件中普遍存在的限制因素，其中约束和尖锐特征会扭曲电流流动，产生局部电流密度热点并导致过早失效。在超导体中，这种效应会抑制序参量并促进涡旋成核，使临界电流降低到本征拆对极限以下。在此，我们证明超导纳米结构的三维成形通过空间电流重新分布克服了几何电流拥挤，建立了一种几何诱导的去拥挤效应。基于含时金兹堡-朗道方程的有限元建模，我们揭示三维收缩结构对中等面内磁场表现出显著且可调的响应——这是平面几何中不具备的功能。这种场控几何结构实现了临界电流调制，并揭示了新的涡旋动力学机制，包括非互易临界电流。此外，曲率和有限厚度通过实现顶点介导的单涡旋线进入，随后其三维分裂为两条涡旋丝，从根本上改变了涡旋成核——这种机制在二维流形中不会发生。我们的发现表明，三维几何工程可作为超导纳米结构的设计范式，为接近拆对极限的器件提供电流分布和涡旋动力学的控制。
英文摘要
Current crowding is a ubiquitous limitation in nanoscale devices, where confinement and sharp features distort current flow, generating localized current-density hotspots and premature failure. In superconductors, this effect suppresses the order parameter and promotes vortex nucleation, reducing the critical current below the intrinsic depairing limit. Here, we demonstrate that 3D shaping of superconducting nanoarchitectures overcomes geometric current crowding through spatial current redistribution, establishing a geometry-induced decrowding effect. Using finite-element modeling based on the time-dependent Ginzburg--Landau equation, we reveal that 3D constrictions exhibit a pronounced and tunable response to moderate in-plane magnetic fields---a functionality absent in planar geometries. This field-controlled geometry enables critical-current modulation and unveils new vortex-dynamics regimes, including a non-reciprocal critical current. Furthermore, curvature and finite thickness fundamentally alter vortex nucleation by enabling apex-mediated entry of single vortex lines, followed by their 3D splitting into two vortex filaments---a mechanism that does not occur in 2D manifolds. Our findings demonstrate 3D geometric engineering as a design paradigm for superconducting nanoarchitectures, offering control over current distribution and vortex dynamics in devices approaching the depairing limit.
发表机构
- Technische Universität Braunschweig（布伦瑞克工业大学）
- FLUXONICS—The European Foundry for Superconducting Electronics e.V.（超导电子欧洲代工厂协会）
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