Electron–phonon coupling constant and critical temperature of some A15 superconducting compounds of Nb and V

Abstract

AbstractTheoretical calculations are made of the coupling constant, λ, for the A15 compounds Nb3Al, Nb3Sn, V3Si, and V3Ge with the help of the theory of Gaspari and Gyorffy. For this purpose Herman‐Skillman potentials are used for the phase shift calculation, and the density of states and the Fermi energy are taken from the band structure calculations of Mattheiss. Using these values of the coupling constant the Tc's are obtained of these materials. These values of Tc's agree fairly well with the experimental values. Since for the highest Tc material, Nb3Ge, no band structure calculation exists, Tc is plotted as a function of the Fermi energy. From the plot, the experimental Tc of 23.2 K is reached for EF = 1.330 Ryd.