Coupling of YCo₂ thin films in a macroscopic ferrimagnet

Abstract
We study here the behavior of YCo₂ thin films when they are decoupled or when they are 3d-coupled in a macroscopic ferrimagnet (MF). The latter consists of YCo₂/GdCo₂/YCo₂, the thickness of each layer (100 nm) being higher than the optical penetration depth. Such a study was done by means of the transverse magneto optic Kerr effect (TMOKE) hysteresis loops and their evolution upon applying a dc field perpendicularly to the easy axis of magnetization. We observe clear differences between magnetically decoupled layers and layers coupled in the MF. The latter case may be understood taken into account that the exchange interaction in the MF is controlled by the existence of a Bloch-type domain wall extending through the layered system.