Patrick F. Henning

Thermal conductivity of Zn, Pr and Tb doped YBCO single crystals: Theory and experiment

The thermal conductivity K(T) vs temperature has been measured for (Y,Pr)Ba2Cu3O7, (Y,Tb)Ba2Cu3O7 and YBa2(Cu,Zn)3O7 single crystals from 10≤T≤280K. For YBa2Cu3O7(YBCO), a strong enhancement in K(T) is observed for T≤Tcwith a peak in K(T) at approximately T≈Tc/2 with a sharp change in slope of K(T) at Tc. These results are similar to those reported previously. For the selectively doped YBCO, the peak in K(T) is shifted to lower temperatures and occurs at T≈ 20K independent of Tc and the impurity concentration. In addition, the sharp change in slope of K(T) at Tc is not apparent for the doped crystals. These results are discussed along with a theoretical model for electronic conduction including both impurity and inelastic scattering from spin fluctuations.

Transport and thermodynamic studies of Y1−xTbxBa2Cu3O7 single crystals

The electrical resistivity ρ(T,x) and magnetic susceptibility χ(T,H), and specific heat C(T,x) have been measured on single crystals of Y1−x TbxBa2Cu3O7. The results strongly suggest the appearance of strong 4f electron hybridization. It becomes apparent that the Tb doped system possesses properties that largely deviate from the well-known behavior of the other high Tc and doped high Tc systems.