Existence of double-pinning force maxima for a single pinning mechanism

Abstract

Critical current measurements on a cold rolled Pb 60In 40 foil show two pinning maxima, one close to H c2 in the neighborhood of h = 0.95, and the other at low fields around h = 0.15. The high field pinning force maximum shifts to lower fields, and the low field maximum shifts to higher fields with increasing pinning strength. The data is explained in terms of Kramer's pinning force model incorporating Brandt's expression for C> 66.