Stability of flat zero-energy states at the dirty surface of a nodal superconductor
Stability of flat zero-energy states at the dirty surface of a nodal superconductor
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节点超导体脏表面平坦零能态的稳定性
DOI：
10.1103/physrevb.95.214503
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发表时间：
2017
影响因子：
3.7
通讯作者：
Asano Yasuhiro
中科院分区：
文献类型：
--
作者：
Ikegaya Satoshi;Asano Yasuhiro
讨论了保持时间反转对称的节点超导体表面高度简并零能态的稳定性。这种表面态的存在是在净极限的受限布里渊区域中定义的非平凡拓扑数的直接结果。然而，在实验中，在真实超导体表面附近，势无序是不可避免的，这可能会提升零能量下的高简并度。我们证明了一个由零能态的手性特征值定义的指标可以用来测量存在势无序时零能的简并度。我们还讨论了索引与拓扑数的关系。
We discuss the stability of highly degenerate zero-energy states that appear at the surface of a nodal superconductor preserving time-reversal symmetry. The existence of such surface states is a direct consequence of the nontrivial topological numbers defined in the restricted Brillouin zones in the clean limit. In experiments, however, potential disorder is inevitable near the surface of a real superconductor, which may lift the high degeneracy at zero energy. We show that an index defined in terms of the chiral eigenvalues of the zero-energy states can be used to measure the degree of degeneracy at zero energy in the presence of potential disorder. We also discuss the relationship between the index and the topological numbers.