ALLOYING EFFECT ON SUPERCONDUCTIVITY IN AMORPHOUS LANTHANUM-BASED ALLOYS

The effect of alloying on the superconducting properties of amorphous, liquid-quenched La-based alloys containing Al, Ge, and Au is studied. The transition temperature Tc of these superconductors depends largely on the La content and is not very sensitive to the second alloy constituent throughout the composition range investigated (∼65-83-at.% La). From the data on Tc, the temperature dependence of the upper critical field Hc2(T), and the residual-resistivity values, we estimate the coherence length ξ(o), the density of states at Fermi level N(EF), and the electron-phonon coupling parameter λ as a function of alloy concentration. The implication of these results is that the electron-phonon interaction strength is essentially constant, suggesting that superconductivity in these alloys is of a localized nature. © 1979 The American Physical Society.