Induced Ising spin-orbit interaction in metallic thin films on monolayer WSe2

Abstract

Spin-orbit interaction (SOI) in superconductors can protect Cooper pairs from external magnetic fields and thus enhance the upper critical field. This effect is most significant in ultrathin superconductor films when the field is in plane. Recently, it was found that this protection is especially efficient in so-called Ising superconductors whose special form of SOI pins the electron spins in the out-of-plane direction and the in-plane critical field is enhanced up to tens of Tesla. We report that a strong SOI can be induced in metallic thin films by proximity to monolayer tungsten diselenide ($\mathrm{WS}{\mathrm{e}}_{2}$), a semiconductor with intrinsic strong Ising SOI. We demonstrate that the upper critical field of the thin-film superconductor is enhanced by the induced SOI, even though the zero-field critical temperature is unchanged or reduced.