Different mechanisms of spin reorientation in exchange coupled double rare earth-transition metal layers with in-plane and perpendicular magnetic anisotropy

The objective of this article is to clarify the spin reorientation effects in exchange coupled layers based on rare earth and transition metals with in-plane and perpendicular anisotropy. These systems are proposed for high density magneto-optical recording with super resolution readout. Two mechanisms are found to be responsible for this change of the magnetization direction with the temperature. The first mechanism is an intrinsic spin reorientation in the GdFeCo layer and the second is the exchange coupling force between the perpendicularly magnetized TbFeCo film and the in-plane GdFeCo film. With appropriate adjustment of the compensation temperatures and the thicknesses of the films, it is possible that the one or the other mechanism dominates. The experimental results are in agreement with a numerical calculation of the magnetization profiles in the coupled system.