Investigation of electron densities of states of superconducting transition metals with nonmagnetic impurity

N. I. Botoshan ; M. I. Vladimir ; V. A. Moskalenko

Teoretičeskaâ i matematičeskaâ fizika, Tome 19 (1974) no. 3, pp. 371-389

Résumé

The densities of electron states of superconducting transition metals with nonmagnetic impurity are calculated in the whole range of frequencies in the limiting cases $\alpha_2\ll1$, $\alpha_1\sim 1$ and $\alpha_1\gg 1$, $\alpha_2\sim 1$ for $\zeta=\Gamma_1/\Gamma_21$. Under these assumptions concerning the parameters $\alpha_n$ and $\zeta$, expressions are obtained for the energy gap $\omega_g$ and a detailed investigation is made of the densities of electron states $n_n(\omega)$ of both bands as functions of the frequency and impurity concentration. It is shown that the density of states $n_1(\omega)$ in the case $\alpha_2\ll1$, $\alpha_1\sim 1$ has two maxima of the same order, one near $\omega_g$ and the other near $\Gamma_2$. The density of states $n_2(\omega)$ has a maximum that is an order of magnitude greater than that of $n_1(\omega)$ in the neighborhood of $\Gamma_2$. In the case of a high impurity concentration ($\alpha_1\gg 1$, $\alpha_2\sim 1$) the energy gap comes close to the order parameter $\Gamma_2$. It is assumed here that $\zeta=\Gamma_1/\Gamma_21$. The maxima of the densities of electron states of both bands, $n_n(\omega)$, are obtained at frequencies near the parameter $\Gamma_2$.