The Effect of Enhanced Spin-Orbit Scattering on the Superconducting - Nonsuperconducting Transition and the Metal-Insulator Transition in Granular Aluminum.

A small amount of bismuth was added to a set of granular aluminum samples to increase the spin-orbit scattering rate. This set is compared with a second set with no bismuth added. With the addition of bismuth, both the metal-insulator transition and the threshold for the presence of superconductivity were shifted a similar amount to higher values of resistivity. The shift of the metal-insulator transition can be explained as a result of the effect of increased spin -orbit scattering at an Anderson transiton. The fact that the superconducting threshold also shifts indicates that it is the proximity to the metal-insulator transition that depresses superconductivity.