Paramagnetically induced gapful topological superconductors

TL;DR

This paper introduces a generic method to transform gapless spin-singlet superconductors into gapful topological superconductors using a Zeeman field, leading to various new TSC phases with potential for 3D Weyl superconductors.

Contribution

It demonstrates how inversion and time-reversal symmetry breaking induce gapful topological phases in 2D spin-singlet superconductors, expanding the classification of TSCs.

Findings

Noncentrosymmetric nodal SCs become gapful under Zeeman field.

Large excitation gaps are achieved in non-s-wave SCs.

Multiple TSC types with nontrivial Chern numbers are identified.

Abstract

We propose a generic scenario for realizing gapful topological superconductors (TSCs) from gapless spin-singlet superconductors (SCs). Noncentrosymmetric nodal SCs in two dimension are shown to be gapful under a Zeeman field, as a result of the cooperation of inversion-symmetry breaking and time-reversal-symmetry breaking. In particular, non-s-wave SCs acquire a large excitation gap. Such paramagnetically-induced gapful SCs may be classified into TSCs in the symmetry class D specified by the Chern number. We show nontrivial Chern numbers over a wide parameter range for spin-singlet SCs. A variety of the paramagnetically-induced gapful TSCs are demonstrated, including D+p-wave TSC, extended S+p-wave TSC, p+D+f-wave TSC, and s+P-wave TSC. Natural extension toward three-dimensional Weyl SCs is also discussed.