Magnetization reversal in exchange-coupled FeTaN/FeSm/FeTaN multilayers

The magnetization reversal process in exchange-spring FeTaN/FeSm/FeTaN multilayers, implementing an alternating soft (FeTaN) and hard (FeSm) magnetic structure, is investigated using magneto-optical Kerr effect vector-magnetometry to measure in plane hysteresis loops both parallel (longitudinal) and perpendicular (transverse) to the applied field. The vector-magnetometry analysis shows that, for soft layer thickness above 3.2 nm, the magnetization reversal occurs via the formation of a stable exchange-spring state in which the magnetic moments of the first soft layer gradually rotate away from the unswitched underlying hard layer. The recording of minor loops shows that the magnetization rotation leading to the exchange-spring state is fully reversible.