Exchange coupling in cobalt-tantalum-permalloy multilayer films

Multilayer magnetic films were deposited by rf sputtering. A Cobalt layer was deposited first and then exposed to air. A Tantalum intermediate layer and a Permalloy top layer were then sputtered. The intermediate layer thickness was varied to study the effect of this thickness on exchange-coupling between the two ferromagnetic layers. Pinhole coupling was observed to occur at a Tantalum thickness of less than 50 Å. This thickness is less than that reported for e-beam evaporated films. The interaction fields for exchange-coupled layers are also lower than those reported for e-beam evaporated films. A film with Permalloy as the bottom layer and Cobalt as the top layer and a Tantalum intermediate layer also exhibited pinhole coupling.