Superconductivity in (Ge,Sn,In)Te thin films

Inversion symmetry breaking enables mixed (s-p) wave pairing in superconductors. IV-VI materials (Sn,Ge)Te host a chemically tunably phase transition from a ferroelectric phase that lacks centrosymmetry close to GeTe to a cubic centrosymmetric phase in SnTe. When alloyed with In this phase diagram coexists with superconductivity. We present our findings on the MBE growth of (Sn, Ge, In)Te thin films by MBE where we consistently observe superconductivity below 1.9K in the centrosymmetric phase up to equal Ge:Sn below. While we do not observe superconductivity in (Ge,In)Te we study the progressive transition to the ferroelectric phase by fine tuning the chemical composition to approach a regime where it coexists with superconductivity. The tunable character of this material family can potentially allow the identification of experimental signatures unique to mixed pairing by studying their behavior across the ferroelectric transition.