Superconductivity in the quasi-one-dimensional ternary compound Ca3Pt4Bi8

Abstract

We report that a quasi-one-dimensional ternary compound Ca3Pt4Bi8 exhibits bulk superconductivity at 0.6 K probed by dc magnetic susceptibility and specific-heat experiments, coexisting with a surface superconductivity at 1.17 K probed by electrical resistivity measurements. The two superconducting phases exhibit significantly different upper critical fields. In electrical resistivity measurements, the resistivity exhibits strong anisotropy and the obtained upper critical field is strongly anisotropic as well, implying two-dimensional (2D) superconductivity. Meanwhile, the bulk upper critical field measured by the dc magnetic susceptibility and specific heat is much smaller than that obtained by electrical resistivity measurements. Moreover, the angular dependence of the upper critical field μ0Hc2 based on the resistivity measurements is consistent with the 2D Tinkham model. Combined with the study of transmission electron microscopy (TEM), 2D superconductivity should occur on the surface of the sample where a thin shell surrounding the bulk phase forms possibly due to a kind of spontaneous chemical change. The first-principles calculations unveil a complicated Fermi surface with ten bands crossing the Fermi level. Some steep bands among these reflect the quasi-one-dimensional nature. This quasi-one-dimensional ternary compound exhibits interesting surface superconductivity in addition to the bulk superconductivity which is worthy of further study.

Source-reported materials — not catalogue approval

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