Collective-Flux-Pinning Phenomena in Amorphous Superconductors

Abstract

The pinning force Fp in amorphous Nb3Ge films with Tc∼4 K has been measured as a function of perpendicular field, temperature, and thickness of the samples. As a result of the large κ and low Jc characteristic of amorphous superconductors the pinning force for the first time is found to be in good agreement with the theory of Larkin and Ovchinnikov for collective pinning extended to the two-dimensional case. Pinning-mediated renormalization of the shear modulus leads to a sharp peak in Fp near the upper critical field. © 1981 The American Physical Society.