Nonmonotonic temperature dependence of the thermal Hall angle of a YBa2Cu3O6.95 single crystal

We have performed high-resolution measurements of the magnetic field (0 T l ess than or equal to B less than or equal to 9 T) and temperature (10 K les s than or equal to T < 140 K) dependence of the longitudinal and transverse Hall thermal conductivity of a twinned YBa2 Cu-3 O-6.95 single crystal. We have used and compared two recently published methods to extract the therm al Hall angle theta (H)(T, B). Our results indicate that cot(theta (H)) var ies quite accurately as T-4 in the intermediate temperature range similar t o 0.3 < T/T-c. It shows a well defined minimum at T-m similar or equal to 2 0 K which resembles that observed in the c-axis microwave conductivity. The electronic part of the longitudinal and the transverse thermal conductivit y show the scaling behavior for transport proper ties predicted for d-wave supercondutors in the temperature range similar to 18 K less than or equal to T less than or equal to 30 K.