DYNAMICS OF THE FLUX-LINE LATTICE IN HIGH-TC OXIDES

An applied a.c. current or magnetic field penetrates into a type-II superconductor by compressional and tilt waves of the flux-line lattice. Accounting for elastic pinning, viscous drag, and linear creep of the flux lines and their images, I derive the complex a.c. penetration depth and linear a.c. resistivity and susceptibility of films and cylinders. Discussed are further nonlinear hysteretic dissipation, thermally activated depinning, thermal fluctuation, flux diffusion, vibrating superconductors, and irreversibility or depinning lines.