We present measurements of thermal conductivity () in the ab plane of untwinned YBa2Cu3O7- (0.10) for T200 K. has been measured with heat flow along both the a and b axes and for two oxygen configurations of the same crystal. The conductivity anisotropy has its maximum value at the conductivity peak (T40 K), where we find a/b1.15 before and after an oxygen anneal. Very little ab anisotropy in the magnitude of is observed in the normal state, though near Tc the temperature dependences are noticeably different for the two directions: d/dT>0 along the b axis and d/dT<0 along the a axis. Near Tc (T110 K) is enhanced slightly for both transport directions, features we attribute to the effect of superconducting fluctuations.
ASJC Scopus subject areas
- Condensed Matter Physics