Temperature evolution of the 1.5-eV absorption band in doped manganites: Formation of Jahn-Teller clusters

A systematic investigation of the absorption spectra of thin films of doped manganites has revealed an anomalous temperature variation of the ∼1.5-eV absorption band. On approaching the insulator-metal transition temperature $T_C$ from the high-temperature side, the band increases in intensity and then merges into the Drude-like band in the ferromagnetic metallic state. We have interpreted the temperature variation in terms of formation and disappearance of Jahn-Teller clusters.