Topological superconductivity in nanowires proximate to a diffusive superconductor–magnetic-insulator bilayer
Topological superconductivity in nanowires proximate to a diffusive superconductor–magnetic-insulator bilayer
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DOI：
10.1103/physrevb.103.134506
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发表时间：
2020-12
影响因子：
3.7
通讯作者：
A. Khindanov;J. Alicea;P. Lee;W. Cole;A. Antipov
中科院分区：
文献类型：
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作者：
A. Khindanov;J. Alicea;P. Lee;W. Cole;A. Antipov
我们研究半导体纳米线耦合到一个双层的无序超导体和磁性绝缘体，最近的实验报告可能的马约拉纳零模式签名在相关架构的动机。具体来说，我们追求一个准经典Usadel方程的方法，对待超导性的双层自洽存在的自旋轨道散射，磁杂质散射，和塞曼分裂诱导的磁性绝缘体和一个补充的应用领域。在这个框架内，我们探讨工程拓扑超导性的纳米线接近双层的前景。我们发现，磁绝缘体诱导的塞曼分裂，通过超导体单独介导，不能诱导拓扑相，因为超导性的破坏（即，Clogston极限）抢占了所需的制度，其中纳米线的塞曼能量超过了诱导的配对强度。然而，这种塞曼分裂确实降低了访问拓扑相变所需的临界施加场，其中与磁性绝缘体的磁化方向反平行的场具有最佳效果。最后，我们表明，磁性杂质散射降低了拓扑相位，和自旋轨道散射，如果存在于超导体中，推的Clogston限制到更高的领域，但同时增加了临界外加场强。
We study semiconductor nanowires coupled to a bilayer of a disordered superconductor and a magnetic insulator, motivated by recent experiments reporting possible Majorana-zero-mode signatures in related architectures. Specifically, we pursue a quasiclassical Usadel equation approach that treats superconductivity in the bilayer self-consistently in the presence of spin-orbit scattering, magnetic-impurity scattering, and Zeeman splitting induced by both the magnetic insulator and a supplemental applied field. Within this framework we explore prospects for engineering topological superconductivity in a nanowire proximate to the bilayer. We find that a magnetic-insulator-induced Zeeman splitting, mediated through the superconductor alone, cannot induce a topological phase since the destruction of superconductivity (i.e., Clogston limit) preempts the required regime in which the nanowire's Zeeman energy exceeds the induced pairing strength. However, this Zeeman splitting does reduce the critical applied field needed to access the topological phase transition, with fields antiparallel to the magnetization of the magnetic insulator having an optimal effect. Finally, we show that magnetic-impurity scattering degrades the topological phase, and spin-orbit scattering, if present in the superconductor, pushes the Clogston limit to higher fields yet simultaneously increases the critical applied field strength.