Separation of Quasiparticle and Phononic Heat Currents in YBa 2 Cu 3 O 7 − δ

Measurements of the transverse ( ${k}_{\mathrm{xy}}$) and longitudinal ( ${k}_{\mathrm{xx}}$) thermal conductivity in high magnetic fields are used to separate the quasiparticle thermal conductivity ( ${k}_{\mathrm{xx}}^{\mathrm{el}}$) of the ${\mathrm{CuO}}_{2}$-planes from the phononic thermal conductivity in $\mathrm{YBa}{}_{2}\mathrm{Cu}{}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$. ${k}_{\mathrm{xx}}^{\mathrm{el}}$ is found to display a pronounced maximum below ${T}_{c}$. Our data analysis reveals distinct transport ( $\ensuremath{\tau}$) and Hall ( ${\ensuremath{\tau}}_{H}$) relaxation times below ${T}_{c}$: Whereas $\ensuremath{\tau}$ is strongly enhanced, ${\ensuremath{\tau}}_{H}$ follows the same temperature dependence as above ${T}_{c}$.