Antiferromagnetic coupling in perpendicularly magnetized Ni/Cu/Ni epitaxial trilayers

The magnetic properties of perpendicularly magnetized Ni/Cu/Ni epitaxial trilayers grown on Si(0 0 1) substrates have been studied. The thickness is 3.3nm for both the Ni layers while the Cu interlayer thickness ranges from 1.83 to 3.66 nm. The M-H loops measured with the magnetic field applied along the axis perpendicular to the film show plateaus characterized by an almost constant value of the magnetization. For specific values of the Cu interlayer thickness, evidence is given regarding an appreciable magnetoresistance effect, which can be explained in terms of an antiferromagnetic coupling between the two Ni films