Spin-dependent hot electron transport in Co/Cu thin films

Hot-electron transport in Co/Cu/Co trilayer films has been studied in the e nergy range from 1.0 to 2.0 eV using ballistic electron magnetic microscopy . Both the spin-dependent attenuation lengths of Co and the cumulative pola rizing effects of spin-dependent tunneling and transmission across a Co/Cu interface have been determined. For very thin (a few Angstrom) Co layers, t he latter effects result in a weakly majority-spin polarized electron beam above similar to 1.3 eV and a minority-spin polarized beam below similar to 1.2 eV. For thicker Co layers the transmitted beam is always majority-spin polarized.