Pair Propagator Approach to Fluctuation-Induced Diamagnetism in Superconductors-Effects of Impurities

We have obtained, within the ladder approximation, expressions for the electron pair propagator of a dilute superconducting alloy (i. e. , subject to the condition ₃1) in the presence of strong magnetic field and above the transition temperature. We then proceed to calculate microscopically the free energy and the magnetization. The procedure used in an earlier work on pure superconductors is justified, but important additional contributions are found for alloys.