Exchange coupling and macroscopic domain structure in a wedged permalloy/FeMn bilayer

Local Kerr effect and magnetometry measurements reveal that switching in exchange-coupled wedged-permalloy/FeMn bilayers involves only two macroscopic domains, extending across the entire sample, separated by a 180^∘{} domain wall, which moves along the wedge direction. The squareness of the hysteresis loop of such exchange-coupled layers depends on the thickness variation of the sample under measurement.