Phonon thermal conductivity in doped $\mathbf{L}{\mathbf{a}}_{\mathbf{2}}\mathbf{C}\mathbf{u}{\mathbf{O}}_{\mathbf{4}}$: Relevant scattering mechanisms

Results of in-plane and out-of-plane thermal conductivity measurements on $\mathrm{L}{\mathrm{a}}_{1.8-\mathrm{x}}\mathrm{E}{\mathrm{u}}_{0.2}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{C}\mathrm{u}{\mathrm{O}}_4$ ($0\le x\le 0.2$) single crystals are presented. The most characteristic features of the temperature dependence are a pronounced phonon peak at low temperatures and a steplike anomaly at $T_{LT}$, i.e., at the transition to the low temperature tetragonal phase (LTT-phase), which gradually decrease with increasing Sr-content. Comparison of these findings with the thermal conductivity of $\mathrm{L}{\mathrm{a}}_{2-\mathrm{x}}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{C}\mathrm{u}{\mathrm{O}}_4$ and $\rm La_2NiO_4$clearlyrevealsthatin$\rm La_{2-x}Sr_xCuO_4$ the most effective mechanism for phonon scattering is impurity-scattering (dopants), as well as scattering by soft phonons that are associated with the lattice instability in the low temperature orthorhombic phase (LTO-phase). There is no evidence that stripe correlations play a major role in suppressing the phonon peak in the thermal conductivity of $\mathrm{L}{\mathrm{a}}_{2-\mathrm{x}}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{C}\mathrm{u}{\mathrm{O}}_4$.