Theory of giant diode effect in d-wave superconductor junctions on the surface of a topological insulator
Theory of giant diode effect in d-wave superconductor junctions on the surface of a topological insulator
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拓扑绝缘体表面d波超导结的巨二极管效应理论
DOI：
10.1103/physrevb.106.214524
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发表时间：
2022
影响因子：
3.7
通讯作者：
Naoto Nagaosa
中科院分区：
文献类型：
--
作者：
Yukio Tanaka;Bo Lu;Naoto Nagaosa
非中心对称量子材料的非互易响应引起了人们的广泛兴趣，这对于二极管的整流功能至关重要。最近的一个突破是超导二极管效应的发现。超导二极管的设计迫切需要一种放大整流效应的原理。本文从理论上研究了拓扑绝缘体（TI）表面的约瑟夫森结S/FI/S（S：-波超导体，FI：铁磁绝缘体）。约瑟夫森电流中同时存在阶数几乎相同的项、项和项，是使两个超导体在TI上的宏观相位差的因子和负因子得到较大值的必要条件。我们发现，通过调节超导体的晶轴和FI的磁化强度，可以产生很大的二极管效应。正、负方向的最大约瑟夫森电流之差约为2倍，电流-相位关系与传统的电流-相位关系相比有很大的改进。零能量Andreev束缚态作为Majorana束缚态在界面上的相关性也被揭示。这一结果为实现低能耗的高效超导二极管铺平了道路。
Nonreciprocal responses of noncentrosymmetric quantum materials attracted recent intensive interests, which is essential for the rectification function in diodes. A recent breakthrough is the discovery of superconducting diode effect. The principle to enlarge the rectification effect is highly desired to guide the design of the superconducting diode. Here, we study theoretically the Josephson junction S/FI/S (S:-wave superconductor, FI: ferromagnetic insulator) on the surface of a topological insulator (TI). The simultaneous existence of,, andterms with almost the same order in the Josephson currentis essential to get larger values of thefactor given bywithand the negative onefor the macroscopic phase differenceof two superconductors on TI. We find that it can show a very large diode effect by tuning the crystal axes of-wave superconductors and the magnetization of FI. The difference of the maximum Josephson currents's between the positive and negative directions can be about a factor of 2, where the current-phase relation is modified largely from the conventional one. The relevance of the zero-energy Andreev bound states as Majorana bound states at the interface is also revealed. This result can pave the way to realize an efficient superconducting diode with low-energy cost.