In-gap states of magnetic impurity in quantum spin Hall insulator proximitized to a superconductor

Abstract

We study the in-gap states of a single magnetic impurity embedded in a honeycomb monolayer proximitized to s-wave bulk superconductor, analyzing a role played by the intrinsic spin-orbit coupling (SOC) introduced by Kane and Mele [Phys. Rev. Lett. 95, 226801 (2005)]. This interaction induces the quantum spin Hall insulating (QSHI) phase with a gap around the Fermi energy. In this gap, spin-polarized states reside, which, via the superconducting proximity effect, evolve into the Shiba-like bound states. We explore their spatial profiles and analyze the quantum phase transition (QPT), where the Shiba-like quasiparticles cross each other leading to abrupt reversal of the local currents circulating around the magnetic impurity. The mutual interplay of the Kane-Mele spin orbit interaction with the proximity induced electron pairing could be important for designing the edge modes of more complex nanostructures, such as magnetic nanowires or islands, in topological superconducting phase.