Irreversible magnetization processes in exchange biased NiO-(Cu)-NiFe films

Summary form only given. Exchange coupling between ferromagnetic and antiferromagnetic films provides a fixed reference magnetization, which is essential for spin-valves in magnetoelectronic devices based on GMR or TMR effects. In this paper the stability of the reference magnetization is addressed by means of domain studies on NiO (10 nm)/Cu (0.5 nm)/Permalloy (10 nm) layers using Kerr microscopy. Low-temperature observation in an optical cryostat was necessary, because the coupling temperature is reduced to about 200K for a 10 nm thick NiO film. The Cu spacer layer reduces, but does not prevent the exchange coupling between Permalloy and NiO.