Thermopower and transport mechanism of the La2−xSrxCu0.94Ti0.06O4 system

The thermal properties and their relationship to the charge transport properties of the La2−xSrxCu0.94Ti0.06O4 solid solution series have been investigated by means of electric resistivity and thermopower measurements. The different changes of the broad peak in S–T curves for Sr-doped samples were observed, which may result from the itinerant hole carriers. The transport mechanism of La2−xSrxCu0.94Ti0.06O4 is mainly dominated by the small-polaron hopping due to the discrepancy in the activation energy derived from the resistivity and the thermoelectric power. The small polarons are not originated from the magnetic coupling between magnetic ions and hole spins, but from the coupling between the phonon with a breathing mode and the hole carriers.