Enhanced suppression of superconductivity in amorphous films with nano-scale patterning

Abstract

We have measured the thickness dependence of the superconducting critical temperature, T c ( d Bi ) , in amorphous Bi/Sb films patterned with a regular array of holes as well as nanoscale thickness variations. We find that the mean field T c is suppressed relative to simultaneously produced unstructured films of the same thickness. Surprisingly, however, the functional form for T c ( d Bi ) , remains unaffected. The role of the thickness variations in suppressing T c is compared to the role of the holes, through parameterization of the surface, as measured through AFM/SEM and a proximity effect calculation. These results suggest that these two nanoscale modifications suppress T c about equally and are consistent with T c being determined on a microscopic length scale.