In-plane thermal conductivity of large single crystals of Sm-substituted(Y1−xSmx)Ba2Cu3O7−δ

Abstract

We have investigated the in-plane thermal conductivityκab(T,H) of large single crystals of optimally oxygen-doped(Y1−x,Smx)Ba2Cu3O7−δ (x = 0, 0.1, 0.2and 1.0) and YBa2(Cu1−yZny)3O7−δ (y = 0.0071) as functions of temperature and magnetic field (along thec axis). For comparison, the temperature dependence ofκab foras-grown crystals with the corresponding compositions is presented. The nonlinear field dependenceof κab for all crystals was observed at relatively low fields near half the critical temperature(Tc). We makefits of the κ(H) data to an electron contribution model, providing both the mean free path of quasiparticles and the electronic thermal conductivityκe, in the absence of a field. The local lattice distortion due to the Sm substitution for Y suppressesboth the phonon and electron contributions. On the other hand, the light Zn doping into theCuO2 planes affects solely the electron component belowTc, resulting in a substantial decrease in .