Thermal conductivity of the c-axis aligned (Bi,Pb) 2Sr 2Ca 2Cu 3O y in the superconducting and mixed states

Abstract

The thermal conductivity of a c-axis aligned BPSCCO polycrystal in the superconducting and mixed states has been studied as a function of temperature and magnetic field up to 14T along the c-axis. Comparing the κ data of a semiconducting sample with those of a metallic sample, an observed anomaly in κ below T c is attributed to the electronic thermal conductivity κ e and seems to be explained by the electronelectron interaction model based on a strong suppression of the quasiparticle scattering rate in the superconducting state. A peak value in κ decreases and its position shifts to higher temperatures with increasing field strength. This behaviour in κ( T) is roughly described by the Kadanoff-Martin expression in κ s e taking into account quasiparticle scattering by quasiparticles in the normal core at several fixed fields. The K-M expression extended to the mixed state qualitatively explains an observed nonlinear field dependence of κ( H) at several fixed temperatures.