Keldysh Ginzburg-Landau action of fluctuating superconductors
Alex Levchenko, Alex Kamenev
DOI 10.1103/PhysRevB.76.094518 · Physical Review B
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Abstract
We derive Ginzburg-Landau action by systematically integrating out electronic degrees of freedom in the framework of the Keldysh nonlinear σ-model of disordered superconductors. The resulting Ginzburg-Landau functional contains a nonlocal Δ-dependent contribution to the diffusion constant, which leads, for example, to Maki-Thompson corrections. It also exhibits an anomalous Gor’kov-Eliashberg coupling between Δ and the scalar potential, as well as a peculiar nonlocal nonlinear term. The action is gauge invariant and satisfies the fluctuation-dissipation theorem. It may be employed, e.g., for calculation of higher moments of the current fluctuations.