Nodal higher-order topological superconductivity from C6-symmetric Dirac semimetals

TL;DR

This paper explores how Dirac semimetals with C6 symmetry can host higher-order topological superconducting states, revealing a new class called HOTDSC characterized by Dirac points and topological properties.

Contribution

It introduces the concept of higher-order topological Dirac superconducting states derived from Dirac semimetals respecting specific symmetries, expanding the understanding of topological superconductivity.

Findings

BdG Dirac points can lead to HOTDSC states instead of HOMA states.

HOTDSC states are characterized by the topology of BdG Dirac points.

The study uses magnetic topological quantum chemistry to identify HOTDSC states.

Abstract

Three-dimensional Dirac semimetals (DSMs) have been shown to exhibit one-dimensional hinge modes which are termed the higher-order hinge Fermi-arc (HOFA) states. They are the topological consequences of Dirac points. Superconducting states from Dirac semimetals can inherit the Dirac points to form nodal Dirac superconducting states, raising a question of whether there exists a topological superconducting bulk-hinge correspondence similar to DSMs. In this work, we discuss the nodal superconducting states from half-filled DSMs respecting non-magnetic (Type-II) Shubnikov space group (SSG) $P6/mmm1'$. We find that the BdG Dirac points can lead to higher-order topological Dirac superconducting (HOTDSC) states instead of the expected higher-order Majorana-arc (HOMA) states. The HOTDSC states can be regarded as a crossing between the HOFAs in normal states and the BdG shadow states. We demonstrate that HOTDSC states can be indicated by relative topologies of BdG Dirac points by utilizing the theory of magnetic topological quantum chemistry (MTQC).