Electric field dependence of the thermal conductivity of a granular superconductor: Giant field-induced effects predicted

The temperature and electric-field dependence of the electronic contribution to the thermal conductivity (TO) of a granular superconductor is considered within a 3D model of inductive Josephson junction arrays. In addition to a low-temperature maximum of zero-field TC kappa(T, 0) (controlled by mutual inductance L-0 and normal state resistivity R-n), the model predicts the two major effects in the applied electric field: (i) the decrease in the linear TC and (ii) the giant enhancement of the nonlinear (i.e. delT-dependent) TC with Deltakappa(T, E)/kappa(T, 0), reaching 500% for parallel electric fields E similar or equal to E-T (E-T = S-0\delT\ is an "intrinsic" thermoelectric field). The possibility of experimentally observing the predicted effects in granular superconductors is discussed. (C) 2002 MAIK "Nauka/Interperiodica".