Magneto-optical Kerr effects in perovskite-type transition-metal oxides:: La1-xSrxMnO3 and La1-xSrxCoO3

Magneto-optical Kerr effects have been investigated for perovskite-type hole-doped oxides La1-xSrxMnO3 (0 less than or equal to x less than or equal to 0.3) and La1-xSrxCoO3 (0 less than or equal to x less than or equal to 0.3) in the photon energy range between 0.9 and 5.3 eV at room temperature. In La1-xSrxMnO3, charge-transfer-type Kerr spectra are observed for the lowest (similar to 1.2 eV) and the second-lowest(similar to 3.5 eV) optical transitions that are likely to arise from electron excitations from the O 2p to the majority-spin e(g) band and to the minority-spin t(2g) band, respectively. In La1-xSrxCoO3, a crystal-field-transition-type Kerr spectrum is observed that is assigned to the electron excitation from the bonding t(2g) Stale to the antibonding e(g) state allowed by the strong hybridization effect between Co 3d and O 2p states. Different characters in the Hund's-rule couplings and covalency seem to cause such a difference in magneto-optical properties between ferromagnetic Mn and Co oxides.