Interpretation of resistivity and thermoelectric power of La0.94Na0.06MnO3: polaron mechanism

The metallic and semiconducting behaviour of electrical resistivity in perovskite manganites La0.94Na0.06MnO3 have been investigated. An effective interionic interaction potential with the long-range Coulomb, van der Waals interaction and the short-range repulsive interaction up to second neighbor ions within the Hafemeister and Flygare approach is formulated to estimate the Debye and Einstein temperature and is consistent with the available experimental data. The electron-phonon and electron-electron interactions are effective to describe the resistivity behaviour for temperatures less than metal-insulator transition TMI. For temperatures, T > TMI, both the semiconducting resistivity and thermoelectric power behaviour supports the polaron hopping conduction. (author)