POLARON TRANSPORT AND LATTICE DYNAMICS IN COLOSSAL-MAGNETORESISTANCE MANGANITES

摘要

Based on the model combining the spin double exchange and the lattice polaron, we have studied the colossal-magnetoresistance phenomena observed in perovskite manganites R(1-x)A(x)MnO(3). First, effects of both the double exchange and the electron-phonon interaction on the transport properties are investigated. We have evaluated the temperature-dependent resistance and the magnetoresistance using the Kubo formula, and examined the crossover from the tunneling to hopping regime of small polarons. Second, effects of the double-exchange interaction on the lattice degree of freedom are explored. It is found that both the hardening of the phonon frequency and a reduction of the phonon damping take place with decreasing the temperature. [References: 25]