MAGNETIC-PROPERTIES OF SANDWICH FILMS BASED ON R-CO AMORPHOUS-ALLOYS (R = RARE-EARTH, Y OR ZR)

The magnetic properties of sandwich films, consisting of a soft amorphous Co-Zr layer placed between two Sm-Co layers with different coercivities, have been studied. Magnetization reversal in the different layers occurs under different field values and domain walls are then created (or annihilated) at the interface, due to the exchange interactions existing between the Co layers. A peculiar magnetization state has been stabilized in which the magnetization in the two Sm-Co layers are of opposite directions and a domain wall divides the Co-Zr central layer into two regions. In this state the magnetization processes are almost completely reversible, in contrast to the irreversible process observed in a single Co-Zr layer. The magnetization reversal mechanisms in this type of systems have been studied in YCo/GdCo bilayer, using transverse Kerr effect measurements. Nucleation/propagation has been found to occur in all instances.