Symmetry-Protected Majorana Fermions in Topological Crystalline Superconductors: Theory and Application to Sr2RuO4

TL;DR

This paper demonstrates how crystal point group symmetry can protect Majorana fermions in topological crystalline superconductors, specifically in Sr2RuO4, and discusses their detection as evidence of a d-vector rotation.

Contribution

It provides a theoretical framework for symmetry-protected Majorana fermions in Sr2RuO4, including conditions and implications for topological phase transitions and experimental detection.

Findings

Majorana fermions are protected by crystal symmetry in Sr2RuO4

A topological phase transition involves a d-vector rotation under magnetic field

Symmetry-protected MFs are identified considering all three bands and spin-orbit interactions

Abstract

Crystal point group symmetry is shown to protect Majorana fermions (MFs) in spinfull superconductors (SCs). We elucidate the condition necessary to obtain MFs protected by the point group symmetry. We argue that superconductivity in Sr2RuO4 hosts a topological phase transition to a topological crystalline SC, which accompanies a d-vector rotation under a magnetic field along the c-axis. Taking all three bands and spin-orbit interactions into account, symmetry-protected MFs in the topological crystalline SC are identified. Detection of such MFs provides evidence of the d-vector rotation in Sr2RuO4 expected from Knight shift measurements but not yet verified.