Interlayer exchange coupling observed by MOKE in Gd/sub x/Co/sub 1-x//Gd/sub x//Co/sub 1-x'/ amorphous bilayers

The magnetic behavior of single layers and bilayers of ferrimagnetic amorphous Gd/sub x/Co/sub 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/sub comp/>300 K and T/sub comp/=230 K for x>0.23 and x=0.21, respectively. For Gd/sub 0.21/Co/sub 0.79//Gd/sub 0.38/Co/sub 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.