A STUDY OF THE MAGNETOOPTICAL KERR SPECTRA OF BULK AND ULTRATHIN FE3O4

An analysis of the complete dielectric tensor of bulk magnetite, Fe3O4 , and of Fe3O4 substituted with a variable degree of Mg2+ or Al3+ allo wed the assignment of the main magneto-optical (MO) transitions in Fe3 O4 between 0.5 and 4.0 eV. This assignment is consistent with our rein terpretation of the MgFe2O4 and Li0.5Fe2.5O4 MO-Kerr spectra. An analy sis of the stoichiometry of a thin Fe3O4 layer is made, based on the K err spectrum, which is compared to an analysis based on the Verwey tra nsition. The Kerr spectrum is also used to compare wavelengths for MO- Kerr effect studies of wedge-shaped samples. (C) 1996 American Institu te of Physics.