Superconducting state in the ternary stannide R3Co4Sn13 (R = Ca, La)

Abstract

We observed the superconducting and normal state by using the single crystals of R3 Co4Sn13 (R=Ca, La). The compounds crystallized in a Yb3Rh4Sn13-type structure with a cubic space group of Pm3¯n (No. 223). Superconducting state of R3Co4Sn13 was investigated by magnetic susceptibility, electrical resistivity, and specific heat measurements. From the electrical resistivity measurements under several magnetic fields, the upper critical field Hc2(0) was estimated. From the results, we discovered that the Hc2(T) curves cannot be described as the Wertharmer–Helfand–Hohenberg (WHH) prediction. Specific heat measurements indicated that these compounds were typical BCS superconductors, and categorized as strong-coupling superconductors.