Small-polaron hopping conduction in La0.9Te0.1MnO3 above the metal-insulator transition

The structure, resistivity, thermopower, and magnetization of the sample La0.9Te0.1MnO3 were investigated. The sample with a rhombohedral structure (R3¯C) undergoes the paramagnetic-ferromagnetic (PM-FM) transition accompanied by an insulator-metal (I-M) transition. Above the I-M transition temperature, a significant difference between the resistivity activation energy (Eρ = 128.3 meV) and the thermopower activation energy (ES = 14.7 meV), a characteristic of small polarons, is observed. In the PM region, the inverse magnetic susceptibility, 1 / χm, is well described by the Curie-Weiss law indicating the absence of the short-range magnetic correlations, which further confirm that the conductivity above the I-M transition temperature for La0.9Te0.1MnO3 is indeed dominated by hopping of the lattice 'small-polaron' rather than hopping of the magnetic 'small-polaron'.