Anisotropic thermal conductivity of superconducting lanthanum cuprate

We have measured the thermal conductivity of a single crystal of La1.96{Sr}0.04CuO₄ in directions both parallel and perpendicular to the copper-oxygen planes. While the effects of electron scattering for in-plane heat transport are strong, the transfer of heat across the CuO₂ planes is limited primarily by sheetlike faults with spacings on the order of 100 A{}. The resulting very high out-of-plane thermal resistivity masks the effects of electron scattering in this direction and prevents a careful study of the anisotropy of the electron-phonon coupling in this superconductor.