MAGNETIZATION, COERCIVE FORCES AND MAGNETORESISTANCE IN SIMPLE AND DOUBLE CO FILMS WITH PERPENDICULAR MAGNETIZATION

Our Au(111)/Co/Au samples show perpendicular spontaneous magnetization for Co thicknesses t below t* = 1.2 nm. Recent RHEED results are in favour of the existence of an important "strain-induced" anisotropy, helping to overcome the shape anisotropy. From the measured parameters of anisotropy and roughness, we propose a quantitative model that explains the fast variation of the perpendicular coercive force with t below t(c). Finally, disymmetric Au/Co(t1)/Au/Co(t2)/Au bilayers (t1 and t2 < t(c)) show enhanced magnetoresistance (5%) in the field range where the layers are magnetized antiparallel.