The change of the Josephson supercurrent density of a weakly-connected granular superconductor in response to externally applied arbitrary thermal gradient dT/dx (nonlinear Seebeck effect) is considered within a model of 3D Josephson junction arrays. For dT/dx>(dT/dx)_c, where (dT/dx)_c is estimated to be of the order of 10^4 K/m for YBCO ceramics with an average grain's size of 10 microns, the weak-links-dominated thermopower S (Seebeck coefficient) is predicted to become strongly dT/dx-dependent.
@article{arxiv.cond-mat/9805368,
title = {Nonlinear Seebeck Effect in a Model Granular Superconductor},
author = {Sergei Sergeenkov},
journal= {arXiv preprint arXiv:cond-mat/9805368},
year = {2009}
}