Polaron transport and lattice dynamics in colossal-magnetoresistance manganites

TLDR: In this article, the spin double exchange and lattice polaron were combined to study the magnetoresistance properties of perovskite manganites, and the effects of the double exchange interaction on the lattice degree of freedom were explored.

Abstract: Based on the model combining the spin double exchange and the lattice polaron, we have studied the colossal-magnetoresistance phenomena observed in perovskite manganites ${\mathrm{R}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{A}}_{\mathrm{x}}$${\mathrm{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.