Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA.
Department of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA.
Nat Commun. 2023 Mar 23;14(1):1628. doi: 10.1038/s41467-023-36786-5.
The suggestion that non-reciprocal critical current (NRC) may be an intrinsic property of non-centrosymmetric superconductors has generated renewed theoretical and experimental interest motivated by an analogy with the non-reciprocal resistivity due to the magnetochiral effect in uniform materials with broken spatial and time-reversal symmetry. Theoretically it has been understood that terms linear in the Cooper pair momentum do not contribute to NRC, although the role of higher-order terms remains unclear. In this work we show that critical current non-reciprocity is a generic property of multilayered superconductor structures in the presence of magnetic field-generated diamagnetic currents. In the regime of an intermediate coupling between the layers, the Josephson vortices are predicted to form at high fields and currents. Experimentally, we report the observation of NRC in nanowires fabricated from InAs/Al heterostructures. The effect is independent of the crystallographic orientation of the wire, ruling out an intrinsic origin of NRC. Non-monotonic NRC evolution with magnetic field is consistent with the generation of diamagnetic currents and formation of the Josephson vortices. This extrinsic NRC mechanism can be used to design novel devices for superconducting circuits.
非互易超导临界电流（NRC）可能是非中心对称超导体的固有性质的这一观点，激发了理论和实验上的新兴趣，其动机是类比于由于具有空间和时间反转对称性破缺的均匀材料中的磁手性效应引起的非互易电阻率。从理论上可以理解，库珀对动量的线性项不会导致 NRC，尽管高阶项的作用仍不清楚。在这项工作中，我们表明在磁场产生的抗磁性电流存在的情况下，多层超导体结构具有临界电流非互易性这一共性。在层间中等耦合的情况下，预计约瑟夫森涡旋将在高磁场和电流下形成。实验上，我们报告了在由 InAs/Al 异质结构制成的纳米线中观察到的 NRC。该效应与线的晶体学取向无关，排除了 NRC 的固有起源。与磁场的非单调 NRC 演化一致的是抗磁性电流的产生和约瑟夫森涡旋的形成。这种外在的 NRC 机制可用于设计超导电路的新型器件。
