Superconductivity in 122-type antimonide BaPt2Sb2
Abstract
The crystal structure, superconducting properties, and electronic structure of a novel superconducting 122-type antimonide, BaPt2Sb2, have been investigated by measurements of powder X-ray diffraction patterns, electrical resistivity, ac magnetic susceptibility, specific heat as well as ab-initio calculations. This material crystallizes in a new-type of monoclinic variant of the CaBe2Ge2-type structure, in which Pt2Sb2 layers consisting of PtSb4 tetrahedra and Sb2Pt2 layers consisting of SbPt4 tetrahedra are stacked alternatively and Ba atoms are located between the layers. Measurements of electrical resistivity, ac magnetic susceptibility and specific heat revealed that BaPt2Sb2 is a superconducting material with a T c of 1.8 K. The electronic heat capacity coefficient γ n and Debye temperature θ D were 8.6(2) mJ/mol K2 and 146(4) K, where the figures in parentheses represent the standard deviation. The upper critical field μ 0H c2(0) and the Ginzburg-Landau coherent length (0) were determined to be 0.27 T and 35 nm. Calculations showed that it has two three-dimensional Fermi surfaces (FSs) and two two-dimensional FSs, leading to anisotropic transport properties. The d-states of the Pt atoms in the Pt2Sb2 layers mainly contribute to N(E F). A comparison between experimental and calculated results indicates that BaPt2Sb2 is a superconducting material with moderate coupling.