Superconducting properties and electronic structure of NaBi

Abstract

Resistivity, dc magnetization, and heat capacity measurements are reported for superconducting NaBi. Tc, the electronic contribution to the specific heat {\gamma}, the {\Delta}Cp/{\gamma}Tc ratio, and the Debye temperature are found to be 2.15 K, 3.4 mJmol-1K-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 250 Oe and 115 nm, respectively. Electronic structure calculations show NaBi to be a good metal, in agreement with the experiments; the px and py orbitals of Bi dominate the electronic states at the Fermi Energy.