Magnetization reorientation in ferrimagnetic double layers

We present experimental results on magnetization reversal for double-layer (GdFeCo/DyFeCo) magneto-optical films. The structure of interest consists of a 40 nm DyFeCo layer with perpendicular magnetization and a 50 nm layer of GdFeCo with in-plane magnetization. A transition from in-plane to perpendicular orientation of the magnetization in GdFeCo film caused by the effect of exchange interaction with DyFeCo has been observed in just a small temperature range. For higher temperatures, the exchange effect becomes smaller and GdFeCo magnetization returns back to in-plane orientation. On the basis of a micromagnetic model, we predict a change in orientation of GdFeCo magnetization from in-plane to perpendicular when it is coupled to DyFeCo film in a certain temperature range. This transition is sensitive to the magnetic properties of each layer that are dependent on temperature and on the values of compensation and Curie temperatures of both GdFeCo and DyFeCo films.