Thermal conductivity and superconductivity inEuBa2Cu3O7−x

We have measured the thermal conductivity $\kappa$ from 2 to 200 K in the superconducting ceramic $\mathrm{Eu}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ observing an anomaly at the superconducting transition temperature $T_c$. Using general arguments and approximations, and supposing that the electrical resistivity is due to electron-phonon interaction, we separate quantitatively the different contributions to $\kappa$. The "observed" electron-limited phonon conductivity fairly follows the Bardeen-Rickayzen-Tewordt theory and a Bardeen-Cooper-Schrieffer-like energy gap with $\frac{2\Delta \mathrm{}\left(0\right)\mathrm{}}{k_B{T}_c}=3.3\mathrm{}\pm 0.7$, in agreement with published data from other kinds of measurements.