Upper critical field in superconductors and the uncertainty principle: Upper limit to the maximum slope of Hc2

Abstract

Consideration of the formulas that give the upper critical field Hc2 near the critical temperature Tc for superconductors in the dirty limit, together with the uncertainty principle, is shown to provide an upper limit to the maximum slope of Hc2. Analysis of reported values shows that amorphous superconductors are in this limit.