THE ROLE OF DIPOLE COUPLING IN MULTILAYERS

This work considers the role of magnetic dipole coupling in multilayer s typically comprising a ferromagnetic material separated by a nonmagn etic metal spacer, e.g., NiFe/Ta. It has been suggested previously tha t dipolar fields may play an important role in the coupling of magneti c layers through a nonmagnetic spacer, in particular where surface rou ghness at the interface is significant. This work considers a first-or der calculation of the dipole coupling energy and magnetic field betwe en two adjacent layers. It is shown that dipole coupling energies orig inating from surface corrugations can behave in the same manner as a c oercive field in terms of dependence on nonmagnetic spacer thickness a nd the degree of roughness. Interestingly, calculations also show that both ferromagnetic- and antiferromagnetic-like coupling can be explai ned in terms of this model. The role of the spacer thickness, magnetic layer thickness, and the form of the roughness is discussed.