Anisotropic third-order magneto-optical Kerr effect

The magnitude of the polar magneto-optical Kerr effect in reflection from t hick iron epitaxial films is experimentally found to strongly depend on the crystallographic orientation of the film, with variations of more than 20% . Similar results are obtained on the (001) and (110) faces of a bulk Fe cr ystal. It is shown that this anisotropy can be described as a third-order e ffect in the magnetization M on the optical response epsilon(omega,M). Our analysis can also be used to understand the transversal Kerr effect at norm al incidence recently observed by Gridnev et al. (C) 1998 American Institut e of Physics. [S0021-8979(98)46611-8].