The magnetic properties of superconducting alloys I

The general Ginzburg - Landau equation valid for all temperatures is derived from the microscopic theory for superconducting alloys where the electronic mean free path 1 is much shorter than the coherence length ₀. Using this equation the magnetic properties of Abrikosov's mixed state as well as the temperature dependence of the upper critical field H₂₀. ₂₅₄₌{₀₄ₗ2} are discussed. It is shown that the Abrikosov structure in the vicinity of the transition point is completely characterized by two parameters ₁ (T) and ₂ (T), both of which coincide at the critical temperature with, the Ginzburg-Landau parameter. A peculiar deviation in the thermodynamical behavior at lower temperatures from Abrikosov's theory is found for superconductors with 1/2.