Time dependence studies on giant magnetoresistive Co/Cu multilayers

Time dependence studies consisting of applying current steps at fixed appli ed fields have been carried out on bilinear and biquadratic giant magnetore sistive (GMR) Co/Cu multilayers in a temperature controlled environment. It has been shown that the voltage responses to current steps of these aged m ultilayers are greater in magnitude before held cycling compared to those m ade after field cycling. Normalized voltage measurements for some samples s uggest a magnetic viscosity effect due to a current step at zero-field is p resent and before field cycling. The effect is reduced after field cycling. This behavior suggests that the effect being seen is purely magnetic in or igin, as only the field is being varied. A ln(t) type function has been cur ve fitted to the zero field voltage response to a current step before field cycling. Voltage measurements made on the Co/Cu films at different field v alues show that as the applied fields are increased the voltage response ha s a reduced In(t) character.