BaPtSi₃: A noncentrosymmetric BCS-like superconductor

Abstract

By investigations of phase relations in the alloy system Ba-Pt-Si at 900 °C we observe the formation of the compound BaPtSi3, which crystallizes in the noncentrosymmetric BaNiSn3 structure type. Its space group is I4mm with the tetragonal lattice parameters a=0.44094(2)nm and c=1.0013(2)nm for the arc-melted compound annealed at 900 °C. The characterization of the physical properties of BaPtSi3 reveals a superconducting transition at 2.25 K with an upper critical field at T=0 K of [approximate]0.05 T. For analyzing the electronic structure, density-functional theory calculations are performed yielding very good agreement between theory and experiment for the structural properties. From relativistic electronic-structure calculations, Fermi surface nesting features are found for two characteristic double sets of bands. The spin-orbit splitting of the relativistic electronic bands is in general rather small at Fermi energy and, therefore, superconductivity adheres to an almost undisturbed BCS state.