Thermopower and thermal conductivity of the electron-doped manganite La0.9Te0.1MnO3.

The thermal properties and their relationship to the charge transport properties of an electron-doped manganite La_0.9Te_0.1MnO₃ were investigated. The resistivity and the Hall effect were measured. The magnetic-field dependence of Hall resistivity indicates that the carriers in La_0.9Te_0.1MnO₃ are electrons. The thermopower S and thermal conductivity κ were also measured. Above the metal-insulator transition temperature T_P, a significant difference between the resistivity activation energy (E_ρ=128.3 meV) and the thermopower activation energy (E_S=14.7 meV) was observed, implying that the conductivity of La_0.9Te_0.1MnO₃ above T_P was dominated by the small-polaron hopping. In the ferromagnetic region, it is found that S shows T^3/2 dependence, suggesting that the electron-magnon scattering strongly affects the low-temperature thermopower of La_0.9Te_0.1MnO₃. The temperature dependence of thermal conductivity, κ(T), reveals that the phonon component (κ_ph) is the major one. Moreover, in the paramagnetic region, a positive dκ/dT is observed, i.e., dκ/dT>0, which might be related to the local anharmonic lattice distortions. [ABSTRACT FROM AUTHOR]