Superconducting properties and electronic structure of NaBi

Abstract

Resistivity, dc magnetization, and heat capacity measurements are reported for superconducting NaBi. T-c, the electronic contribution to the specific heat gamma, the Delta C-p/gamma T-c ratio, and the Debye temperature are found to be 2.15 K, 3.4 mJ mol(-1) K-2, 0.78, and 140 K respectively. The calculated electron-phonon coupling constant (lambda(ep) = 0.62) implies that NaBi is a moderately coupled superconductor. The upper critical field and coherence length are found to be 250Oe and 115nm, respectively. Electronic structure calculations show NaBi to be a good metal, in agreement with the experiments; the p(x) and p(y) orbitals of Bi dominate the electronic states at the Fermi Energy.