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 κ(T, 0) (controlled by mutual inductance L0 and normal state resistivity Rn), 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. ∇T-dependent) TC with Δκ(T, E)/κ(T, 0), reaching 500% for parallel electric fields E≃ ET(ET=S0|∇T| is an “intrinsic” thermoelectric field). The possibility of experimentally observing the predicted effects in granular superconductors is discussed.