Doped manganites and polaron behavior

Doped manganites belong to strongly correlated materials that demonstrate the strong influence of electron-phonon coupling on properties such as transport and magnetism. The transport properties of oxide materials can be described by the polaron model, and for epitaxial doped manganite films in the paramagnetic state, by the small polaron hopping model that also provides parameters such as the thermal hopping energy for carriers. By using a formula that we derived for the relationship between the ferromagnetic ordering temperature and exchange coupling caused by hopping polarons, a simulation was performed with the experimental data of epitaxial doped manganite films in applied magnetic fields. The good agreement between the experimental data and energy balance expression indicates that the simulation is reasonable. Based on these results, the colossal magnetoresistance effect for doped manganites is discussed.