Superconductivity in Pt-doped ScPdBi single crystals*

ScPdBi and ScPtBi are non-centrosymmetric isostructural half-heusler semimetals with different topological character as determined by the band inversion parameter, Δ = Γ₈ − Γ₆, where Γ₆ and Γ₈ have s- and p-like electronic characters, respectively. Electronic structure calculations show that ScPdBi is very close to band inversion, with △ = −0.7eV. Nei- ther compound is superconducting above 0.08 K. Substitution of Pt on the Pd-site in ScPdBi is expected to enhance spin-orbit coupling (SOC) and induce band inversion, but remarkably it also induces superconductivity. Neither ScPdBi or ScPtBi is superconducting above .08K, but a superconducting transition below 1.2K with an upper critical field of H_C2(0) ≈ 1.6T is observed in electrical resistivity measurements carried out on a single crystal of ScPt_xPd_1−xBi (x=0.06). Magneto-transport measurements above 1.2K are well fitted to weak anti-localization expressions, indicating that the superconductivity emerges in a two-dimensional conductor. In agreement, no indication of bulk superconductivity is found in specific heat measurements and no Meissner effect is observed. The linear temperature dependence of the upper critical field H_C2(T) suggesting unconventional superconductivity.