Nonlinear magneto-optical Kerr spectra of thin ferromagnetic iron films calculated with ab initio bandstructure theory

We show that the nonlinear Kerr effect reveals sensitively the geometrical and magnetic structure of surfaces and interfaces. We present calculations of the film-thickness dependent nonlinear magneto-optical Kerr spectra for thin bcc Fe films within a slab geometry using the spin-polarized full-potential linear muffin-tin orbital method. Our results show clearly that the nonlinear Kerr spectra of thin films are characteristicaly different from those at surfaces of bulk materials and moreover reflect more sensitively film features such as magnetic moments and substrate effects than linear spectra which are also calculated. In the case of linear Kerr spectra of Au/Fe(_bcc)/Au(001) films our theoretical results are in good agreement with observed frequency- and thickness-dependent spectra.