Majorana multipole response of topological superconductors

Shingo Kobayashi; Ai Yamakage; Yukio Tanaka; Masatoshi Sato

doi:10.1103/physrevlett.123.097002

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arXiv · 1812.01857

Majorana multipole response of topological superconductors

Shingo Kobayashi·Ai Yamakage·Yukio Tanaka·Masatoshi Sato

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Abstract

In contrast to elementary Majorana particles, emergent Majorana fermions (MFs) in condensed-matter systems may have electromagnetic multipoles. We developed a general theory of magnetic multipoles for surface helical MFs on time-reversal-invariant superconductors. The results show that the multipole response is governed by crystal symmetry, and that a one-to-one correspondence exists between the symmetry of Cooper pairs and the representation of magnetic multipoles under crystal symmetry. The latter property provides a way to identify nonconventional pairing symmetry via the magnetic response of surface MFs. We also find that most helical MFs exhibit a magnetic-dipole response, but those on superconductors with spin-3/2 electrons may display a magnetic-octupole response in leading order, which uniquely characterizes high-spin superconductors. Detection of such an octupole response provides direct evidence of high-spin superconductivity, such as in half-Heusler superconductors.

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Shingo Kobayashi, Ai Yamakage, Yukio Tanaka, Masatoshi Sato. 2018-12-05. Majorana multipole response of topological superconductors. https://doi.org/10.1103/physrevlett.123.097002

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