Separation of Quasiparticle and Phononic Heat Currents in YBCO

Abstract

Measurements of the transverse (k_{xy}) and longitudinal (k_{xx}) thermal conductivity in high magnetic fields are used to separate the quasiparticle thermal conductivity (k_{xx}^{el}) of the CuO_2-planes from the phononic thermal conductivity in YBa_2Cu_3O_{7-δ}. k_{xx}^{el} is found to display a pronounced maximum below T_c. Our data analysis reveals distinct transport (τ) and Hall (τ_H) relaxation times below T_c: Whereas τis strongly enhanced, τ_H follows the same temperature dependence as above T_c.