Thermopower Studies of Polycrystalline Ag Doped LaMnO Manganites.

The effects of silver doping on the magnetotransport and thermopower of LaAgMnO (0.05≤ x≤0.30) have been investigated. For the sample with x=0.05, temperature dependent resistivity exhibits an insulating behavior, while thermopower is found to be large and negative over the measured temperature range. An increase in the Ag doping enhances the conductivity and shifts the metal-insulator transition temperature toward high temperature side. The low temperature thermopower data has been explained in terms of diffusion, magnon drag, and phonon drag effects and found that the magnon drag effect dominates in this region. Finally, the electrical transport in the high temperature region has been analyzed by using adiabatic small polaron hopping mechanism. [ABSTRACT FROM AUTHOR]