Theoretical investigation of the orientation dependence of the magneto-optical Kerr effect in Co

The first-principles spin-polarized, relativistic linear muffin-tin orbital method has been applied to calculate electronic and magneto-optical properties of Co in both fcc and hcp structures. In particular, the magneto-optical properties have been calculated for several magnetization directions in order to study their magnetization orientation dependences. A pronounced anisotropy in the polar Kerr effect is found for hcp Co while the magneto-optical properties of fcc Co are predicted to be insensitive to the magnetization direction. Moreover, this magneto-optical anisotropy in hcp Co is found to be correlated with the presence of a large anisotropy in the orbital magnetic moment and orbital hyperfine field. Changing the structure from fcc to hcp gives rise to even greater changes in the magneto-optical properties of Co. Calculated Kerr angles and ellipticities are in reasonable agreement with the latest experiment.