Giant magnetoresistance in Co/Cu multilayers: Influence of Co thickness at the first antiferromagnetic maximum

The dependence of the magnetoresistive properties of Co/Cu multilayers on the thickness of the Co layers is described for the case when the Cu layer thickness is 9 Å, corresponding to the first antiferromagnetic maximum. Both the width and the height of the peaks in the magnetoresistance/field curves decrease with increasing Co layer thickness in the range 5–50 Å. This leads to an optimum Co layer thickness of 30–40 Å that maximizes the sensitivity to changes in magnetic field. This result may have practical significance for applications that require the relative lack of hysteresis that is found at the first antiferromagnetic maximum.