NMR diagnosis of pseudo-scalar superconductivity in 3D Dirac materials

Abstract

Recently observed 4π periodic Andreev bound states in 3D Dirac materials are attributed to conventional superconducting pairing. Our alternative explanation in terms of a novel form of parity breaking pseudo-scalar superconducting order can be sharply diagnosed by nuclear magnetic resonance relaxation rate. The left–right symmetry breaking of the pseudo-scalar superconductivity can be directly probed as an anti-peak structure below TC in sharp contrast to the conventional Hebel–Slichter peak.