Magnetoresistance and galvanomagnetics in bias sputtered Co/Cu multilayers

Co/Cu multilayers have been prepared on glass substrates by sputtering with negative substrate bias voltage. In zero biased films, the magnetoresistance (MR) increases monotonically with the Cu layer thickness (d_Cu) up to 40 Å, resulting from decoupling between the ferromagnetic layers. On the other hand, for -30-V biased films, three oscillation peaks with a period of about 12 Å appear in the d_Cu dependence of the MR ratio because of the RKKY-like interlayer coupling. In the oscillation peak at d_Cu=24 Å, a sharp MR change occurs at low applied magnetic field, owing to a very small coupling constant of J =0.008 erg/cm². The Hall resistivity and the planar Hall effect have been also measured