Upper Critical Field Changes in Electron‐Irradiated Niobium

Abstract

Abstract Measurements are reported of the dependence of the upper critical field H c 2 on the concentration and configuration of Frenkel defects in niobium. The defects were produced by low‐temperature irradiation with 3 MeV electrons and subsequent annealing treatments. The results qualitatively confirm a theory by Eilenberger which predicts that H c 2 not only depends on the electronic mean free path but also on the ratio between s‐ and p‐wave scattering of the defects.