Kagome晶格拓扑超导态的自旋轨道耦合效应  

The spin-orbit coupling effect on the topological superconducting properties of Kagome lattice

作　　者：高全 李意芝 孟利军 GAO Quan;LI Yizhi;MENG Lijun(Hunan Key Laboratory of Micro-Nano Energy Materials and Devices,School of Physics and Optoelectronics,Xiangtan University,Xiangtan 411105,China)

机构地区：[1]湘潭大学物理与光电工程学院,微纳能源材料与器件湖南省重点实验室,湖南湘潭411105

出　　处：《湘潭大学学报（自然科学版）》2024年第5期112-122,共11页Journal of Xiangtan University(Natural Science Edition)

基　　金：国家自然科学基金(11204261);湖南教育厅重点项目(19A471)。

摘　　要：该文基于Kagome晶格的紧束缚模型和Bogoliubov-de Gennes方程,使用数值对角化方法系统地研究了自旋轨道耦合(SOC)作用对Kagome晶格拓扑超导态的影响.通过计算得到的块体Kagome超导体的超导带隙(E_(gap))和陈数(N_(C)),以及Kagome纳米条带的能谱,深入分析了Rashba自旋轨道耦合(RSOC)和本征自旋轨道耦合(ISOC)在手性d+id波Kagome超导体中引起的拓扑相变以及边界态发生的演化.结果表明,RSOC可以引起N_(C)从4转变到-2的拓扑相变,并产生新的边界态,同时引发原来的边界态向拓扑平庸的演化.这种能够被ISOC破坏且穿过了零能级的平庸边界态导致了N_(C)与边界态数目的不对应.在ISOC和RSOC的共同作用下会引起丰富的拓扑相变,但ISOC不能破坏或产生受粒子空穴对称性保护的边界态,因此在边界态上无法反映这些拓扑相变.Based on the tight-binding model of Kagome lattice and Bogoliubov-de Gennes equation,this paper investigates systematically the effect of spin-orbit coupling(SOC)on a topological superconducting(TSC)state of Kagome lattice through the numerical diagonalization method.By calculating the superconducting gap(E_(gap))and the Chern number(N_(C))of the Kagome bulk,and the energy spectra of the Kagome nanoribbon,the topological phase transition and the evolution of the edge states induced by Rashba SOC(RSOC)and intrinsic SOC(ISOC)on a chiral d+i d wave Kagome superconductor are analyzed.The results indicate that the RSOC can induce a new TSC phase with N_(C)from-2 to 4,a new topologically protected edge mode emerges,and the original topological edge modes turn into trivial simultaneously.Such zero-energy-crossed trivial edge states can be break by ISOC and cause the mismatch between N_(C) and the number of edge states.Rich TSC phases emerge when RSOC and ISOC are both presented,but the ISOC cannot break nor induce the particle-hole symmetry protected edge states,thus the topological phase transitions cannot be reflected on the edge states.

关 键 词：拓扑超导体 Kagome晶格 拓扑相变 自旋轨道耦合效应 Majorana边界态 体边对应关系 

分 类 号：O469[理学—凝聚态物理]