Thermal diffusion of quasiparticles and vortices in high-temperature superconductors

Abstract

In the mixed state of high-temperature superconductors (HTSC) vortex motion under the influence of the Lorentz force of an applied transport or shielding current has been studied in a large number of experiments. Recently, an increasing amount of work has concentrated also on the transport effects due to the thermal force acting on the quasiparticles and vortices in an applied temperature gradient, resulting in the Nernst and Seebeck effect. We summarize the highlights of these latter experiments. In particular, we address the following subjects: origin of the Seebeck effect in the mixed state, transport entropy of the vortex structure in strongly anisotropic HTSC's, Hall contribution to the Nernst and Seebeck effect, and measurements in the fluctuation regime. From the temperature dependence of the transport energy of the vortices the slope ϑ H c2/ϑ T near T c, the coherence length and the Ginzburg-Landau parameter can be determined.