Effect of Zn doping and oxygen stoichiometry on the thermal conductivity of YBa2Cu3O7-δ

The temperature dependence of the electronic contribution κe to the thermal conductivity of a two-dimensional superconductor with Van Hove singularities (VHSs) in the density of states is calculated. The influence of the position of these VHSs from the Fermi level is investigated. Various experimental results on the thermal conductivity of YBa2(Cu1-xZnx)3O7-δ compounds with 0 ≤ x ≤ 0.017 and 0 ≤ δ ≤ 0.3 are analysed using the above model. A simple relation between x and δ can be extracted from this analysis. This relation is shown to be correlated with the variation of the Cu(2) valence with oxygen content and Zn doping.