In-plane magnetization of an ultrathin film ofFe3O4(111)grown epitaxially on Pt(111)

The magnetic properties of an eight-monolayer ${\mathrm{Fe}}_3{\mathrm{O}}_4\mathrm{}\left(111\right)\mathrm{}$ film grown epitaxially on Pt(111) have been studied by the magneto-optic Kerr effect (MOKE) and conversion electron Mössbauer spectroscopy. The MOKE results indicate that a saturation of the magnetization is achieved with a field of about 500 Oe. In zero field the magnetization remains saturated. Apart from a paramagnetic contribution of 11%, which is interpreted as originating from the interface layer, the Mössbauer spectrum is identical to that of bulk ${\mathrm{Fe}}_3{\mathrm{O}}_4.$ Furthermore, the data indicate that all the magnetic moments are in the plane of the film.