Majorana corner states in a two-dimensional magnetic topological insulator on a high-temperature superconductor
Majorana corner states in a two-dimensional magnetic topological insulator on a high-temperature superconductor
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DOI：
10.1103/physrevb.98.245413
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发表时间：
2018-06
影响因子：
3.7
通讯作者：
Tao Liu;J. J. He-J.;F. Nori
中科院分区：
文献类型：
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作者：
Tao Liu;J. J. He-J.;F. Nori
传统的$n$维拓扑超导体（TSC）具有无带隙的$（n - 1）$维边界态.与此相反，二阶TSC的特征在于拓扑保护的无间隙$（n - 2）$维状态与通常的间隙$（n - 1）$-边界。在这里，我们研究了二阶TSC与二维（2D）磁拓扑绝缘体（TI）邻近耦合到高温超导体，其中马约拉纳束缚态（MBS）定位在角落的正方形样品与带隙的边缘模式。由于这里考虑的混合系统的镜像对称性，有两个在每个角落的两种情况下的MBS：d波和$s_{\pm}$波超导配对。我们提出了相应的拓扑相图的磁交换相互作用和配对振幅的作用。详细的分析，基于边缘理论，揭示了起源的存在MBSs的角落的2D样品，这是由于狄拉克质量的符号变化出现在任何两个相邻的边缘的交叉点，由于配对对称性。可能的实验实现进行了讨论。我们的建议提供了一个有前途的平台，实现MBS和执行可能的非阿贝尔编织在2D系统。
Conventional $n$-dimensional topological superconductors (TSCs) have protected gapless $(n - 1)$-dimensional boundary states. In contrast to this, second-order TSCs are characterized by topologically protected gapless $(n - 2)$-dimensional states with usual gapped $(n - 1)$-boundaries. Here, we study a second-order TSC with a two-dimensional (2D) magnetic topological insulator (TI) proximity-coupled to a high-temperature superconductor, where Majorana bound states (MBSs) are localized at the corners of a square sample with gapped edge modes. Due to the mirror symmetry of the hybrid system considered here, there are two MBSs at each corner for both cases: d-wave and $s_{\pm}$-wave superconducting pairing. We present the corresponding topological phase diagrams related to the role of the magnetic exchange interaction and the pairing amplitude. A detailed analysis, based on edge theory, reveals the origin of the existence of MBSs at the corners of the 2D sample, which results from the sign change of the Dirac mass emerging at the intersection of any two adjacent edges due to pairing symmetry. Possible experimental realizations are discussed. Our proposal offers a promising platform for realizing MBSs and performing possible non-Abelian braiding in 2D systems.