COUPLING OF YCO2 THIN-FILMS IN A MACROSCOPIC FERRIMAGNET

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 lat ter 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) hysteresi s loops and their evolution upon applying a de field perpendicularly t o the easy axis of magnetization. We observe clear differences between magnetically decoupled layers and layers coupled in the MF. The latte r case may be understood taken into account that the exchange interact ion in the MF is controlled by the existence of a Bloch-type domain wa il extending through the layered system..