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arXiv 2003.05414cond-mat.supr-concond-mat.mes-hall
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拓扑约瑟夫森结中的平面约瑟夫森霍尔效应

Planar Josephson Hall effect in topological Josephson junctions

Oleksii Maistrenko, Benedikt Scharf, Dirk Manske, Ewelina M. Hankiewicz

摘要:

基于三维拓扑绝缘体的约瑟夫森结为实现非传统的$p$波配对和Majorana模提供了有趣的可能性。在这里,我们提供了一个均匀的磁化在正常区域的效果的详细研究:我们展示了如何之间的相互作用的自旋动量锁定的拓扑绝缘体和平行于相位偏置方向的面内磁化导致的Andreev谱相对于横向动量的不对称性。如果足够大,这种不对称性诱导从无间隙,反向传播马约拉纳模式的制度过渡到一个制度与未受保护的模式是单向的小横动量。有趣的是,磁化引起的Andreev谱的不对称性也引起约瑟夫森霍尔效应,即横向约瑟夫森电流的出现。详细研究了约瑟夫森霍尔电流的幅值和电流相位关系。特别是,我们展示了如何磁控制和门控的正常区域可以使相当大的约瑟夫森霍尔电流相比,纵向约瑟夫森电流。最后,我们还提出了平面磁场作为正常区域磁化的替代,并讨论了如何在实验中观察到平面约瑟夫森霍尔效应。

英文摘要:

Josephson junctions based on three-dimensional topological insulators offer intriguing possibilities to realize unconventional $p$-wave pairing and Majorana modes. Here, we provide a detailed study of the effect of a uniform magnetization in the normal region: We show how the interplay between the spin-momentum locking of the topological insulator and an in-plane magnetization parallel to the direction of phase bias leads to an asymmetry of the Andreev spectrum with respect to transverse momenta. If sufficiently large, this asymmetry induces a transition from a regime of gapless, counterpropagating Majorana modes to a regime with unprotected modes that are unidirectional at small transverse momenta. Intriguingly, the magnetization-induced asymmetry of the Andreev spectrum also gives rise to a Josephson Hall effect, that is, the appearance of a transverse Josephson current. The amplitude and current phase relation of the Josephson Hall current are studied in detail. In particular, we show how magnetic control and gating of the normal region can enable sizable Josephson Hall currents compared to the longitudinal Josephson current. Finally, we also propose in-plane magnetic fields as an alternative to the magnetization in the normal region and discuss how the planar Josephson Hall effect could be observed in experiments.

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