LEVEL STATISTICS INSIDE THE CORE OF A SUPERCONDUCTIVE VORTEX

A microscopic theory of the Efetov supermatrix sigma-model type is con structed for the low-lying electron states in a mixed superconductive- normal system with disorder. This technique is used for the study of t he localized states in the core of a vortex in a moderately clean supe rconductor with tau (-1) much greater than omega(0) similar to Delta(2 )/E-F. At low energies epsilon much less than omega(Th) similar to (om ega(0)/tau) (1/2), the energy level statistics is described by the ''z ero-dimensional'' limit of this supermatrix theory, and the result for the density of states is equivalent to that obtained within Altland-Z irnbauer random matrix model. Nonzero modes of the sigma model increas e the mean interlevel distance by the relative amount [2 In (1/omega(0 )tau)](-1). (C) 1998 American Institute of Physics.