DOMAIN AND DOMAIN-WALL OBSERVATIONS IN SPUTTERED EXCHANGE-BIASED WEDGES

Sputtered exchange-coupled sandwich systems with FeMn biasing underlayer, NiFe and NiCo ferromagnetic layers and wedge shaped Ru interlayers were investigated by Kerr microscopy. Domain analysis confirms the basic oscillatory behavior between ferro- and antiferromagnetic exchange coupling as a function of the non-magnetic interlayer thickness. High resolution observation reveals many 360-degrees domain walls especially in zones of weak coupling. These 360-degrees walls act as nucleation sites in a strongly hysteretic magnetization process and may form a problem in sensor applications.