In-plane thermal conductivity of large single crystals of Sm-substituted (Y$_{1-x}$Sm$_{x}$)Ba$_{2}$Cu$_{3}$O$_{7-\delta}$

TL;DR

This study examines the in-plane thermal conductivity of large single crystals of Sm-substituted YBa2Cu3O7−δ, revealing how Sm and Zn doping influence phonon and electron contributions, with implications for understanding quasiparticle behavior in high-Tc superconductors.

Contribution

It provides detailed measurements of thermal conductivity as functions of temperature and magnetic field for Sm- and Zn-doped YBa2Cu3O7−δ crystals, and models the electron contribution to thermal transport.

Findings

Sm substitution suppresses phonon and electron thermal contributions.

Zn doping affects only the electronic component below Tc, reducing quasiparticle mean free path.

Nonlinear field dependence of thermal conductivity observed near half Tc.

Abstract

We have investigated the in-plane thermal conductivity $\kappa_{ab}(T,H)$ of large single crystals of optimally oxygen-doped (Y$_{1-x}$,Sm$_{x}$)Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ ($x$=0, 0.1, 0.2 and 1.0) and YBa$_{2}$(Cu$_{1-y}$Zn$_{y}$)$_{3}$O$_{7-\delta}$($y$=0.0071) as functions of temperature and magnetic field (along the c axis). For comparison, the temperature dependence of $\kappa_{ab}$ for as-grown crystals with the corresponding compositions are presented. The nonlinear field dependence of $\kappa_{ab}$ for all crystals was observed at relatively low fields near a half of $T_{c}$. We make fits of the $\kappa(H)$ data to an electron contribution model, providing both the mean free path of quasiparticles $\ell_{0}$ and the electronic thermal conductivity $\kappa_{e}$, in the absence of field. The local lattice distortion due to the Sm substitution for Y suppresses both the phonon and electron contributions. On the other hand, the light Zn doping into the CuO $_{2}$ planes affects solely the electron component below $T_{c}$, resulting in a substantial decrease in $\ell_{0}$ .