Switching behaviour of patterned SmCo5 thin films investigated by magnetic force microscopy

The domain structure of highly coercive, epitaxial SmCo5 thin films with well-defined direction of the easy axes in the film plane was studied to understand the nature of the magnetization process. For magnetic force microscopy (MFM) measurements, the film was patterned to obtain square-shaped elements and magnetized up to 5 T to adjust different remanent states for imaging the domain structure. Upon applying an external field, the stray field contrast inside the element reduces and magnetic charges of opposite sign build up at the two edges of the squares perpendicular to the field direction. Small areas within the element remain oppositely magnetized even in fields larger than the coercivity and only vanish upon full saturation at about 5 T, indicating a pinning dominated switching behaviour.