Gapless Triplet Superconductivity in Magnetically Polarized Media

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.