Thermal conductivity of Er-Ba-Cu-O and Ho-Ba-Cu-O superconducting bulks.

We have measured the temperature dependence of the in-plane thermal conductivity, kab(T), for both Er-Ba-Cu-O and Ho-Ba-Cu-O superconducting bulks. The absolute values of kab(T) for both bulks are smaller than that of Y-Ba-Cu-O bulk, but are larger than that of Dy-Ba-Cu-O bulk, which is known to show an anomalous small kab. kab(T) for Ho-Ba-Cu-O shows a positive slope (dkab/dT>0) in the normal state, similarly to that for Dy-Ba-Cu-O. On the other hand, a slightly negative slope (dkab/dT<0) is found for Er-Ba-Cu-O. The out-of-plane thermal conductivity, kc, was also measured for Er-Ba-Cu-O bulk, and the anisotropy in the thermal conductivity, (kab/kc), was estimated to be about 2. [ABSTRACT FROM AUTHOR]