Spin-triplet Superconductivity in Nonsymmorphic crystals

TL;DR

This paper demonstrates that nonsymmorphic crystalline symmetries can significantly promote spin-triplet superconductivity, even with weak spin-orbit coupling, by protecting spin-sublattice-momentum locking in electronic bands.

Contribution

It reveals a novel mechanism where nonsymmorphic symmetries facilitate spin-triplet pairing, expanding the understanding of conditions favoring this rare superconducting state.

Findings

Spin-triplet pairing can dominate in nonsymmorphic crystals with weak spin-orbit coupling.

Nonsymmorphic symmetry protects spin-sublattice-momentum locking in electronic bands.

The study uses space group P4/nmm to illustrate the mechanism and suggests experimental signatures.

Abstract

Spin-triplet superconductivity is known to be a rare quantum phenomenon. Here we show that nonsymmorphic crystalline symmetries can dramatically assist spin-triplet superconductivity in the presence of spin-orbit coupling. Even with a weak spin-orbit coupling, the spin-triplet pairing can be the leading pairing instability in a lattice with a nonsymmorphic symmetry. The underlining mechanism is the spin-sublattice-momentum lock on electronic bands that are protected by the nonsymmorphic symmetry. We use the nonsymmorphic space group P4/nmm to demonstrate these results and discuss related experimental observables. Our work paves a new way in searching for spin-triplet superconductivity.