Superconductivity of M I(M II0.5,Si 0.5) 2 (M I=Sr and Ba, M II=Al and Ga), ternary silicides with the AlB 2-type structure

Abstract

Ternary silicides M I(M II0.5,Si 0.5) 2 (M I=Sr and Ba, M II=Al and Ga) were prepared by Ar arc melting. Powder X-ray diffraction indicates that they have the AlB 2-type structure, in which Si and M II atoms are arranged in honeycomb layers and M I atoms are intercalated between them. Electrical resistivity and dc magnetization measurements revealed that Sr(Al 0.5,Si 0.5) 2 is superconductive, with a critical temperature for superconductivity ( T C) of 4.2 K, while Ba(Al 0.5,Si 0.5) 2 is not at temperatures ranging above 2.0 K. Sr(Ga 0.5,Si 0.5) 2 and Ba(Ga 0.5,Si 0.5) 2 are also superconductors, with T Cs of 5.1 and 3.3 K, respectively.