Thermodynamics of the Two-Band Superconductors in the Presence of Nonmagnetic Impurities

The thermodynamics of the two-band model for the superconducting states of transition metals containing nonmagnetic impurities are developed using the Green's-function technique. The thermodynamic functions of the system are expressed in terms of the densities of state of the $s$ and $d$ electrons. Changes caused by the presence of the impurities of the various functions are obtained. It is shown that in the intraband limit $g_{\mathrm{sd}}=0\mathrm{}$, the specific heat of transition metals in the superconducting phase is decreased because of the presence of the nonmagnetic impurities.