涡旋河流与超导MgB$_2$薄膜中的多重电压转变
Vortex rivers and multiple voltage transitions in superconducting MgB$_2$ thin films
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中文总结 AI 辅助
基于含时金兹堡-朗道方程模拟超导薄膜中不同无序类型下的电流-电压特性，发现晶界缺陷导致多重电压转变，细长缺陷产生电压台阶，L形缺陷形成线性区段，并分析序参量演化及实验可行性。
中文摘要 AI 辅助
涡旋动力学决定了第二类超导体的耗散和磁电阻特性。在大输运电流下，处于混合态的超导体其电流-电压（$I$-$V$）特性通常表现出非线性上扬，随后因磁通流动不稳定性而发生突变跳跃。然而，也可能出现其他转变行为，包括形成相滑移线和正常态区域。哪种机制占主导取决于样品的均匀性、样品尺寸相对于相干长度和穿透深度的大小，以及电子能量弛豫和热移除的速率。本文基于含时金兹堡-朗道方程，对具有不同类型无序的超导薄膜的$I$-$V$曲线进行了数值模拟。对于晶界缺陷网格，我们发现了多重电压转变叠加在$I$-$V$曲线的非线性上扬之上。对于随机排列的细长缺陷，$I$-$V$曲线表现出电压台阶；而对于垂直于输运电流取向的L形缺陷，$I$-$V$曲线则显示出由电压转变分隔的扩展线性区段。我们分析了沿$I$-$V$曲线序参量的演化，并讨论了所揭示动力学机制在实验上的可观测性。
英文摘要
Vortex dynamics govern the dissipation and magneto-resistive properties of type-II superconductors. At large transport currents, the current-voltage ($I$-$V$) characteristics of a superconductor in the mixed state usually exhibit a nonlinear upturn followed by an abrupt jump occurring due to a flux-flow instability. However, other transition behaviors are also possible, including the formation of phase-slip lines and normal domains. Which mechanism dominates depends on the sample uniformity, its dimensions relative to the coherence length and penetration depth, and the rates of electron energy relaxation and heat removal. Here, based on the time-dependent Ginzburg-Landau equation, we present the results of numerical modeling of the $I$-$V$ curves of superconducting films with various types of disorder. For a grain-boundary defect mesh, we find multiple voltage transitions overlaid with a nonlinear upturn of the $I$-$V$ curves. For randomly arranged elongated defects, the $I$-$V$ curves exhibit voltage steps, whereas for L-shaped defects oriented perpendicular to the transport current, the $I$-$V$ curves show extended linear regimes separated by voltage transitions. We analyze the evolution of the order parameter along the $I$-$V$ curves and discuss the experimental accessibility of the revealed dynamics regimes.
发表机构
- Technische Universität Braunschweig（布伦瑞克工业大学）
- University of Vienna（维也纳大学）
- Université de Lorraine-CNRS（洛林大学-法国国家科学研究中心）
- FLUXONICS—The European Foundry for Superconducting Electronics e.V.（FLUXONICS——欧洲超导电子铸造协会）
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