Exchange coupling in FeTaN/FeSm/FeTaN multilayers: a Kerr effect study

The dependence of the interlayer coupling on both the soft (FeTaN) and hard (FeSm) layer thickness in
FeTaN-FeSm-FeTaN multilayers, deposited by dc magnetron sputtering, has been investigated. The magnetization reversal
process is examined experimentally using a magnetooptical Kerr effect. The exchange field ex, which is a measure of the average
coupling between the soft and hard layers, was determined from the field shift of the minor hysteresis loop. The value of ex
increases as the number of the soft FeTaN layer increases. A significant and fully reversible transverse hysteresis loop was
measured indicating that, during the magnetization-reversal process, the magnetic moments in the soft layers rotate reversibly,
as typical of exchange-spring systems.