Magnetization processes and magnetic domain structure in weakly coupled GdCo/Si/Co trilayers

The magnetization reversal in weakly coupled GdCo(13 nm)/Si(0.8 - 2 nm)/Co(8 nm) trilayers has been studied by conventional magnetometry and layer-selective Kerr microscopy. In a very weakly coupled trilayer system the Co layer reverses by the propagation of 180°-walls and the GdCo layer remagnetises by the nucleation and growth of patch-like domains nucleating at 360°-walls. A decrease of the non-magnetic separating layer thickness results in the magnetization reversal of both layers as a whole at low fields. Further field increase induces a magnetization reversal of the GdCo layer by the nucleation and growth of domains acting against the interlayer coupling.