Thermoelectric and thermomagnetic effects in the mixed state of high-TcsuperconductingTl2Ba2CaCu2Ox

We have measured the longitudinal thermoelectric effects (Seebeck and Peltier effect) and the transverse thermomagnetic effects (Nernst and Ettingshausen effect) in the mixed state of the same ${\mathrm{Tl}}_2$ ${\mathrm{Ba}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{\mathit{x}}$ single crystal. The longitudinal effects were found to be in agreement with the behavior expected from the diffusion of quasiparticles in a temperature gradient or electric field, and consistency with the Thomson relation was observed. The Nernst effect showed the qualitative behavior expected from the thermal diffusion of vortices in a temperature gradient. For the ${\mathrm{Tl}}_2$ ${\mathrm{Ba}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{\mathit{x}}$ single crystal we obtain a value of the transport entropy of ${\mathit{S}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$=0.3×${10}^{\mathrm{-}15}$ J/K m at B=1 T. The transport entropy ${\mathit{S}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$ derived from the Nernst-effect measurements showed the reduction expected for B∥c for a highly anisotropic material, where the standard Abrikosov vortices degenerate into ‘‘pancake vortices’’ confined to the ${\mathrm{CuO}}_2$ sheets. Because of this reduction of ${\mathit{S}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$, the Ettingshausen effect was below the detection limit of our experiments.