Proximity-induced superconductivity generated by thin films: Effects of Fermi surface mismatch and disorder in the superconductor
Proximity-induced superconductivity generated by thin films: Effects of Fermi surface mismatch and disorder in the superconductor
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DOI：
10.1103/physrevb.106.085429
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发表时间：
2022-08-15
影响因子：
3.7
通讯作者：
Das Sarma, Sankar
中科院分区：
文献类型：
--
作者：
Stanescu, Tudor D.;Das Sarma, Sankar
基于三维微观模型的精确数值分析，我们研究了超导薄膜的无序特性对薄膜(如半导体)产生的邻近感生超导电性的影响。为了使问题在数值上易于处理，我们使用递归格林函数方法和“修补方法”相结合，这种方法利用了界面格林函数在无序存在时的短程性质。由于超导(SC)和半导体(SM)之间的费米面失配，再加上约束诱导的横向SC模量子化，清洁的SC膜引起的邻近效应通常比体相SC的相应量小一到三个数量级，并表现出巨大的厚度变化。无序的存在有相互竞争的效应：一方面，它增强了近邻诱导的超导电性，抑制了它强烈的厚度依赖性，另一方面，它在SM中产生了近邻诱导的有效无序。非微扰地研究了近邻诱导无序对拓扑超导相及其相关的Majorana模的影响。
We investigate the effects of disorder characterizing a superconducting thin film on the proximity-induced superconductivity generated by the film (in, e.g., a semiconductor) based on the exact numerical analysis of a three-dimensional microscopic model. To make the problem numerically tractable, we use a recursive Green's function method in combination with a "patching approach" that exploits the short-range nature of the interface Green's function in the presence of disorder. As a result of the Fermi surface mismatch between the superconduc-tor (SC) and the semiconductor (SM) in combination with the confinement-induced quantization of the transverse SC modes, the proximity effect induced by a clean SC film is typically one to three orders of magnitude smaller that the corresponding quantity for a bulk SC and exhibits huge thickness-dependent variations. The presence of disorder has competing effects: on the one hand, it enhances the proximity-induced superconductivity and suppresses its strong thickness dependence, on the other hand, it generates proximity-induced effective disorder in the SM. The effect of proximity-induced disorder on the topological superconducting phase and the associated Majorana modes is studied nonperturbatively.