Two-phase scenario for the metal-insulator transition in colossal magnetoresistance manganites

Abstract

Recent experiments indicate the coexistence of localized and itinerant charge carriers close to the metal-insulator transition in the ferromagnetic phase of colossal magnetoresistive manganese perovskites. For a theoretical description of the colossal magnetoresistance transition we propose a two-phase model of competing insulating polaronic and ferromagnetic metallic phases with equal hole densities. We find that the subtle balance between these two phases with distinctly different electronic properties can be readily influenced by varying physical parameters, producing various ``colossal'' effects, such as the large magnetization and conductivity changes in the vicinity of the transition temperature.