Spin reorientation transition in (111) textured L1 ₀ CoPt layers

In this work, a spin reorientation transition from [001] axis to an in-plane direction occurs near Curie temperature under a small external field for (111) textured L1 ₀ CoPt layers in an AlN/CoPt multilayer film, indicating the dominant role of the shape anisotropy at elevated temperatures over the magnetocrystalline anisotropy. A large in-plane residual magnetization is also observed after cooling the sample from a temperature above the Curie point. The formation of magnetization during cooling is considered due to the alignment of magnetic moments along the easy axis by the small field in the spin reorientation transition temperature region. Our work reveals the importance of shape anisotropy for the formation of magnetization in the heat assisted magnetic recording process.