MAGNETIZATION PROCESSES IN EXCHANGE-COUPLED DOUBLE-LAYER FILMS WITH INPLANE AND PERPENDICULAR ANISOTROPY

Magnetic curves in exchange-coupled double layers (ECDL) with planar a nd perpendicular anisotropies are experimentally determined by Faraday measurements. In order to interpret unusual hysteresis loops, we have extended the model of Kobayashi applied to our systems. We show that all possible ECDL films can be grouped in two bilayer types. In the fi rst one, the sublattice magnetization of transition metal (TM) and rar e earth (RE) of each layer rotates coherently with external magnetic f ield and we call this Type P (parallel). In the second type, the TM (r eap. RE) magnetization of the first-layer rotates in the opposite dire ction to the corresponding magnetization of the second layer and we ca ll this Type A (antiparallel). By changing the film composition or its temperature, we can obtain a transition from one type to the other wi th also a change of the magnitude of the interface energy which can be measured experimentally. (C) 1998 Elsevier Science B.V. All rights re served.