POLARON ABSORPTION IN A PEROVSKITE MANGANITE LA0.7CA0.3MNO3

Temperature dependent optical conductivity spectra of a La0.7Ca0.3MnO3 (LCMO) sample were measured. In the metallic regime at very low tempe ratures, they clearly showed two types of absorption features, i.e., a sharp Drude peak and a broad midinfrared absorption band, which could be explained as coherent and incoherent bands of a large lattice pola ron. Electrodynamic analyses suggest that the elementary excitation in LCMO should be in a strong couplings regime and have interactions wit h the spin degree of freedom.