Gapless Triplet Superconductivity in Magnetically Polarized Media

TL;DR

This paper demonstrates that in magnetically polarized media, a specific triplet pair density wave state can dominate, leading to gapless superconductivity and impacting the realization of Majorana fermions for quantum computing.

Contribution

It introduces the staggered d-wave $$-triplet TPDW superconducting state as a dominant phase in polarized media, explaining gapless superconductivity phenomena.

Findings

The $$-triplet TPDW state can coexist with or replace homogeneous triplet SC states.

Gapless superconductivity occurs when only the TPDW state is present.

Distinct tunneling density of states and thermodynamic signatures identify triplet SC regimes.

Abstract

We reveal that in a magnetically polarized medium, a specific commensurate triplet pair density wave (TPDW) superconducting (SC) state, the staggered d-wave $\Pi$-triplet state, may coexist with homogeneous triplet SC states and even dominate eliminating them under generic conditions. When only this TPDW SC state is present, we have the remarkable phenomenon of gapless superconductivity. This may explain part of the difficulties in the realization of the engineered localized Majorana fermion modes for topological quantum computation. We point out qualitative characteristics of the tunneling density of states, specific heat and charge susceptibility that identify the accessible triplet SC regimes in a spinless medium.