THERMAL-CONDUCTIVITY OF BI2SR2CACU2O8 IN THE MIXED-STATE

We have investigated ab-plane thermal conductivity in single crystals of Bi2Sr2CaCu2O8 in the mixed state. We find that the ab-plane thermal conductivity, kappa ab, below Tc depends on the magnitude and orientation of the magnetic field. A simple empirical expression was found for kappa ab(H perpendicular to c), which suggests that electron component of kappa ab is responsible for the normal state behavior of the ab-plane thermal conductivity. However, the kappa ab anomaly in the superconducting state is attributed to an increase in its phonon component and a rapid decrease of quasiparticle scattering below Tc.