Superconductivity in "Amorphous" Transition-Metal Alloy Films

The superconducting transition temperatures of "amorphous" transition-metal alloys have been measured. The variation of Tc as a function of the electron-to-atom ratio is consistent with the presence of an atomiclike parameter characterizing the systematics of Tc, with, however, an unexplained peak at the half-filled d shell. The data do not support a recent explanation based entirely on a simple averaging or smearing of the crystalline electronic density of states.