INVESTIGATION OF THE STOICHIOMETRY OF MBE-GROWN FE3O4 LAYERS BY MAGNETOOPTICAL KERR SPECTROSCOPY

The polar Kerr spectra between 0.7 and 4.0 eV of single-crystalline la yers of Fe3O4 grown epitaxially on MgAl2O4, SrTiO3 and MgO (100) subst rates by means of oxidic molecular beam epitaxy are compared to the sp ectrum of a bulk synthetic single crystal of magnetite to asses the st oichiometry of the layers. Model calculations of the magneto-optical s pectra of thin layers are used to explain the differences between the spectra of bulk Fe3O4 and thin layers of Fe3O4. The observed differenc es are attributed to interference effects and oxidation of the surface of the thin layers. The results are compared to magnetisation and Ver wey transition data.