Direct experimental investigation of spin-reorientation phase transitions in an antiferromagnetic CoNiCu/Cu superlattice

The characteristic features of phase transitions induced by an external magnetic field and of the corresponding changes in the relative orientations of the spins in the ferromagnetic CoNiCu layers of a multilayer film, which are coupled by an antiferromagnetic exchange interaction via nonmagnetic Cu interlayers, are studied using a magnetooptic method for visualizing the fringing fields. It is established that the magnetization reversal process in this nanocomposite material proceeds by a spin-flop orientational phase transition on account of the formation and motion of specific domain walls as well as by incoherent rotation of the spins toward the applied field. It is shown that, depending on the direction of the external magnetic field with respect to the easy axis, asymmetric canted phases also arise as a result of such transitions. Pis’ma Zh. Tekh. Fiz. 64, No. 11, 778–782 (10 December 1996)