SPIN-POLARIZED ELECTRON-ENERGY-LOSS SPECTROSCOPY ON EPITAXIAL FCC CO LAYERS ON CU(001)

The magnetism and the electronic structure of epitaxial fcc Co/Cu(001) films were investigated by spin-polarized electron-energy-loss spectroscopy (SPEELS). Strong spin-flip scattering reveals an exchange splitting of 0.8 eV and a Stoner gap of 300 meV, independent of thickness. Films above 2 monolayers (ML) thickness show ferromagnetic order at room temperature, while the monolayer Co/Cu(001) cannot be remanently magnetized above 80 K. SPEELS spectra from monolayer films are very similar to spectra from bulklike films (20 ML) and display no evidence for enhanced magnetic moments. SPEELS spectra from the bare Cu(001) substrate exhibit a gradual increase of spin-flip scattering for loss energies above 2 eV, while SPEELS data from disordered CoO show sharp loss features, which can be interpreted in terms of ligand-field theory.