Magnetic and transport properties of sputter deposited Ni/Co multilayers

We have fabricated multilayer Ni/Co thin films by sputter deposition. For films in which the overall thickness was kept constant and the ratio of Co to Ni is 1:1 there is an increase of coercivity as the bilayer thickness is reduced below 2 nm. For films with a thickness of 63 nm, the coercivity rises from below 2.5 kA/m in a film with a bilayer thickness of 3 nm to 30 kA/m for a bilayer thickness of 1 nm. The equivalent composition alloy film shows a coercivity of below 2.5 kA/m. High coercivity is also observed if only one of the constituent layers has a thickness less than 1 nm. For even thickness Ni and Co individual layers and a constant overall film thickness we find that the film resistivity increases with interface density. For a constant overall film thickness the anisotropic magnetoresistance effect is seen to be inversely proportional to the film resistivity