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arXiv 2002.01715cond-mat.supr-conphysics.ins-det
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局部非均匀磁场中的约瑟夫森结

Josephson junctions in a local inhomogeneous magnetic field

V. M. Krasnov

摘要:

在各种实验条件下,约瑟夫森结都可能受到局部的、强不均匀的磁场的作用。在这里,这个问题进行了分析和数值。本文导出了含时局域场的修正sine-Gordon型方程,并在静态和动态情况下进行了数值求解。两个具体的例子被认为是当地的领域:诱导由Abrikosov涡,或由一个尖端的磁力显微镜(MFM)。结果表明,随时间变化的局域场可以诱导一个动态的磁通流状态的结穿梭,或单向棘轮状约瑟夫森涡运动。这提供了通过振荡MFM尖端检测和操纵约瑟夫森涡旋的机制。在静态情况下,局部场会导致临界电流与磁场($I_c(H)$)调制模式的失真。畸变对局部场的形状和幅度都很敏感。因此,$I_c(H)$图案携带关于结内的局部场分布的信息。这开启了采用单个约瑟夫森结作为扫描探针传感器的可能性,其空间分辨率不受其几何尺寸的限制,从而避免了传感器的场灵敏度和空间分辨率之间的折衷的已知问题。

英文摘要:

A Josephson junction can be subjected to a local, strongly inhomogeneous magnetic field in various experimental situations. Here this problem is analyzed analytically and numerically. A modified sine-Gordon type equation in the presence of time-dependent local field is derived and solved numerically in static and dynamic cases. Two specific examples of local fields are considered: induced either by an Abrikosov vortex, or by a tip of a magnetic force microscope (MFM). It is demonstrated that time-dependent local field can induce a dynamic flux-flow state in the junction with shuttling, or unidirectional ratchet-like Josephson vortex motion. This provides a mechanism of detection and manipulation of Josephson vortices by an oscillating MFM tip. In a static case local field leads to a distortion of the critical current versus magnetic field, $I_c(H)$, modulation pattern. The distortion is sensitive to both the shape and the amplitude of the local field. Therefore, the $I_c(H)$ pattern carries information about the local field distribution within the junction. This opens a possibility for employing a single Josephson junction as a scanning probe sensor with spatial resolution not limited by its geometrical size, thus obviating a known problem of a trade-off between field sensitivity and spatial resolution of a sensor.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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