Spin Directions in Exchange-Coupled Rare-Earth Transition Metal Double Layer Films with In-Plane Magnetic Intermediate Layer

Abstract

Exchange-coupled perpendicular anisotropy rare earth-transition metal (RE-TM) double layer films with application as direct overwrite magneto-optical media have been studied employing the Hall effect. An intermediate layer was inserted between a RE-dominated TbDyFeCo layer and a TM-dominated TbFeCo layer in order to modify the exchange interaction. In the case of an in-plane magnetic anisotropy TM-dominated GdCo intermediate layer, the Gd-Co layer was inferred from the Hall effect to be almost fully magnetized in the normal direction at zero applied magnetic field and room temperature. Furthermore, an in-plane domain wall exists inside the TbDyFeCo layer at zero field when the magnetizations of the TbDyFeCo and TbFeCo layers are parallel. It was also found that the in-plane wall moves to the interface between the TbDyFeCo and GdCo layers at a temperature of about 50°C and further into the intermediate layer at higher temperatures.