Revisiting the case for negative Nernst signals in extreme type-II superconductors

Different transport coefficients have been measured in High-Tc superconductors to pinpoint the nature of the pseudogap phase. In particular, the thermoelectric coefficients received considerable attention both theoretically and experimentally. We numerically simulate the Nernst effect in extreme type-II superconductors using time-dependent Ginzburg-Landau equations. We report a sign reversal of the thermoelectric coefficient, αxy, at temperatures close to the mean-field transition temperature TcMF(H), which qualitatively agrees with recent experiments on high-Tc materials. We also discuss the noise power spectrum of αxy, which shows 1/fβ behavior. Based on this observation, we propose an experiment to determine different regimes of vortex dynamics by measuring the noise correlations of the Nernst signal.