Interlayer exchange coupling observed by MOKE in GdxCo 1-x/Gdx/Co1-x´ amorphous bilayers

The magnetic behavior of single layers and bilayers of ferrimagnetic amorphous Gd_xCo_1-x (0.38>x>0.21), where the thickness of the individual layer was 100 nm, was analyzed by bulk magnetometry (VSM, AGM) and transverse Kerr effect (TMOKE) in the temperature range of 10 K-300 K. The compensation temperatures were: T_comp>300 K and T_comp=230 K for x>0.23 and x=0.21, respectively. For Gd_0.21Co_0.79 /Gd_0.38Co_0.62 bilayers, the strong Co-Co exchange coupling at the interface gives rise to a macroscopic ferrimagnet behavior for the net magnetizations of the bilayer when T>230 K. Otherwise, reversible coherent rotation of the magnetization was observed when the field is applied perpendicular to the as-grown in-plane uniaxial easy axis of the bilayer