Two-band superconductivity of Sn 1– x In x Te crystals with T c = 3.6–3.8 K

The Andreev reflection spectra of high-quality superconducting Sn1–x In x Te crystals with critical temperature T c = 3.6–3.8 K were examined. The two-band nature of the superconducting state of this compound was established. The energy gaps have s-symmetry and were measured to be 2Δ1/kT c = 3.5 ± 0.9 and 2Δ2/kT c = 7 ± 1. Neither of the contacts with a resistance of 1.5–23 Ω revealed a peak at zero voltage typical of the topological superconducting state.