Majorana multipole response: General theory and application to wallpaper groups
Majorana multipole response: General theory and application to wallpaper groups
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DOI：
10.1103/physrevb.103.224504
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
S. Kobayashi;Y. Yamazaki;A. Yamakage;M. Sato
中科院分区：
文献类型：
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作者：
S. Kobayashi;Y. Yamazaki;A. Yamakage;M. Sato
时反不变性拓扑超导体表面的涌现马约拉纳费米子具有电磁结构并实现独特的电磁响应。本文在拓扑分类和群论的基础上，发展了时反不变性超导体表面Majorana费米子电磁响应的一般理论。特别是，我们提供了一个分类的可能的电磁响应所产生的拓扑结构和晶体对称性之间的相互作用的紧急马约拉纳费米子。研究发现，出现的Majorana费米子具有偶极或八极序磁结构，单个Majorana Kramers对的磁响应与库珀对对称性直接相关：在晶体对称性下，磁结构和库珀对具有共同的不可约表示.这一结果为通过表面自旋敏感测量识别拓扑超导体中的非常规库珀对提供了新的视角。我们还确定了一组没有磁偶极子响应的晶体对称性，这导致磁八极响应作为主要贡献。这样的磁八极响应提供了一个独特的指示奇异的拓扑超导体，如拓扑超导体与$J=3/2$电子或非对称。我们还澄清，多个克拉默对给出了电响应。
Emergent Majorana fermions on surfaces of time-reversal invariant topological superconductors host electromagnetic structures and realize unique electromagnetic responses. In this paper, we develop a general theory of electric and magnetic responses of the surface Majorana fermions on time-reversal invariant superconductors, on the basis of topological classification and the group theory. In particular, we provide a classification of possible electromagnetic responses of the emergent Majorana fermions arising from the interplay between topology and crystalline symmetry. It is found that the emergent Majorana fermions host magnetic structures with dipole or octupole order, and the magnetic response of a single Majorana Kramers pair directly links to Cooper pair symmetry: the magnetic structure and the Cooper pairs have a common irreducible representation under crystalline symmetry. This result provides a new perspective for the identification of unconventional Cooper pairings in topological superconductors through surface-spin-sensitive measurements. We also identify a set of crystalline symmetries without magnetic dipole response, which leads to a magnetic octupole response as the leading contribution. Such a magnetic octupole response provides a unique indication of exotic topological superconductors like topological superconductors associated with $J=3/2$ electrons or nonsymmorphic symmetry. We also clarify that multiple Kramers pairs give an electric response.