FLUX-FLOW RESISTIVITY IN MODEL HIGH-TEMPERATURE SUPERCONDUCTORS

We calculate the resistivity of a model "high-temperature superconductor" consisting of a simple-cubic arrangement of superconducting "grains" coupled together by resistively shunted Josephson junctions. The effects of temperature are simulated by Langevin noise in each junction. We find a strong magnetoresistance for magnetic fields both parallel and perpendicular to the applied current, in agreement with the results of Kwok et al. [Phys. Rev. Lett. 64, 966 (1990)]. When the magnetic field B and the current density J make an angle-phi, the resistivity at sufficiently high temperatures roughly obeys the law-rho(B, T, phi) = rho(B, T) + DELTA-rho sin2(phi) in agreement with experiment. The resistivity is strongly dependent on current density. At zero magnetic field it is found to satisfy the scaling relation E = xi--1-zF+/-(J-xi(d-1)PHI-0/ck(B)T), where E is the electric field, c is the speed of light, J is the current density, d is the dimensionality, and F+/- are scaling functions which apply above and below T(c). The dynamical critical exponent is estimated for this model as 1.5+/-0.5.