Level statistics inside the core of a superconductive vortex

Skvortsov M.A., Kravtsov V.E., Feigel'man M.V.

PACS: 73.23.-b, 74.40.+k

**Microscopic theory of the type of Efetov's supermatrix sigma-model is constructed for the low-lying electron states in a mixed superconductive-normal system with disorder. This technique is used for the study of the localized states in the core of a vortex in a moderately clean superconductor with τ**^{-1} ^ ωο ~ *Δ*^{2}/Ερž . At low energies e <C ”C *ijJth ***~ (ωο/τ)**^{1}/^{2}, the energy level statistics is described by the "zero-dimensional" limit of this supermatrix theory, and the result for the density of states is equivalent to that obtained within Altland-Zirnbauer random matrix model. Nonzero modes of the sigma-model increase the mean interlevel distance by the relative amount [21η(1/ωοτ)]^{_1}.