A study of the magneto-optical 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+ allowed the assignment of the main magneto‐optical (MO) transitions in Fe3O4 between 0.5 and 4.0 eV. This assignment is consistent with our reinterpretation of the MgFe2O4 and Li0.5Fe2.5O4 MO‐Kerr spectra. An analysis of the stoichiometry of a thin Fe3O4 layer is made, based on the Kerr spectrum, which is compared to an analysis based on the Verwey transition. The Kerr spectrum is also used to compare wavelengths for MO‐Kerr effect studies of wedge‐shaped samples.