Surface effects on the electrodynamics of a type-II superconductor in the mixed state

Effects of deformation of flux lines on electrodynamics is investigated near the surface of a type-II superconductor in the mixed state when dc magnetic field is perpendicular to the surface. One- and two-mode approximations to the problem are presented. It is shown that the surface effects can be described by an effective boundary condition for a dense flux line lattice (B much greater than H-cl, where H-cl is the lower critical field) in the two-mode approximation. This condition determines the relative value of the amplitudes of the modes. (C) 2001 Elsevier Science B.V. All rights reserved.