MAGNETIZATION-DEPENDENT BEHAVIORS OF INTERBAND-TRANSITIONS BETWEEN THE EXCHANGE-SPLIT BANDS IN DOPED MANGANITE FILMS

The temperature dependence of absorption spectra for thin films of dou ble-exchange ferromagnet R0.6Sr0.4MnO3 has been investigated with vari ation of the one-electron bandwidth W. With decreasing temperature, wh ich corresponds to the increase of the magnetization M, a large amount of spectral weight transfers from the high-(similar to 3 eV) to low-( less than or equal to 1 eV) energy region. We ascribe these transition s to the interband transition between the bands split by the on-site e xchange interaction J and the intraband transition within the lower ba nd, respectively. This suggests that optical excitations in the visibl e region strongly couple with local spin alignments in these doped man ganites.