VORTEX MOTION IN INHOMOGENEOUS SUPERCONDUCTORS - LINEAR-RESPONSE

The vortex motion in inhomogeneous superconductors is described within a percolation model. The flux-line response at small driving currents is linear in the Lorentz force and can be mapped on impedance network s. The frequency-dependent linear magnetoconductivity of inhomogeneous superconductors is calculated numerically by simulations of random im pedance networks. Near the percolation threshold the conductivity disp lays a scaling behavior consistent with the scaling laws observed expe rimentally in high-temperature superconductors. The scaling functions are calculated for the first time. The critical exponents as well as t he scaling functions of the three-dimensional percolation problem are in good agreement with experimental values for twinned YBa2Cu3O7-delta crystals.