Heat transport of La2-yEuyCuO4 and La1.88-yEuySr0.12CuO4 single crystals -: art. no. 184512

To study the rare-earth doping effect on the phonon heat transport of La-based cuprates and shed light on the mechanism of phonon scattering, both ab-plane and c-axis thermal conductivities (kappa(ab) and kappa(c)) are measured for La2-yEuyCuO4 (y = 0, 0.02 and 0.2) and La1.88-yEuySr0.12CuO4 (y = 0 and 0.2) single crystals. It is found that the phonon peak (at 20-25 K) in kappa(ab)(T) of La2-yEuyCuO4 shows an anomalous Eu-doping dependence: it completely disappears for y = 0.02, which is discussed to be due to the local lattice distortions around Eu dopants, and reappears for y = 0.2 with much smaller peak magnitude compared to y = 0 sample. In contrast to the strong suppression of the phonon peak in Eu-doped La2CuO4, Eu-doping to La1.88Sr0.12CuO4 enhances the low-T phonon heat transport that results in the reappearance of the phonon peak in this charge-carrier-doped system. The data clearly show that the establishment of static stripe phase rather than the structural change is responsible for the reappearance of phonon peak.