Vortex Density of States and Absorption in Clean Layered Superconductors
  We study the spectrum of the states localized in the vortex cores in the mixed state of clean layered superconductors. S-wave coupling is assumed. It is found that in a large region of parameters adjacent to the superclean case a new universal (i.e. independent of the density of impurities) class of level statistics arises. It is the circular unitary random matrix ensemble. The density of states for such conditions is calculated. The absorption resulting from the Landau-Zener transitions between these levels is different from the classical result for an isotropic three-dimensional system. 
A. A. Koulakov and A. I. Larkin