Yu-Shiba-Rusinov states and topological superconductivity in Ising paired superconductors

Abstract

An unusual form of superconductivity, called Ising superconductivity, has recently been uncovered in mono- and few-layered transition metal dichalcogenides. This 2D superconducting state is characterized by the so-called Ising spin-orbit coupling (SOC), which produces strong oppositely oriented effective Zeeman fields perpendicular to the 2D layer in opposite momentum space valleys. We examine the Yu-Shiba-Rusinov (YSR) bound states localized at magnetic impurities in Ising superconductors and show that the unusual SOC manifests itself in unusually strong anisotropy in magnetic field response of zero bias conductance peaks observable in STM experiments on impurity sites. For a chain of magnetic impurities with moments parallel to the plane of Ising superconductors we show that the low energy YSR band can host topological superconductivity and Majorana fermions as a direct manifestation of Ising spin-orbit coupling induced topological effects.