Exchange coupling in double layer systems using Co-based multilayer thin films

We have studied the exchange coupling in a double-layered structure consisting of the memory and reference layers of e-beam evaporated Co-based multilayer thin films. The structures of the specimens were examined by X-ray diffractometer and the magnetic and magnetooptic properties were measured by VSM and Kerr spectrometer. X-ray diffractometry revealed that all of the specimens had multilayer structure. The exchange coupling between the double layers was so strong that the magnetization reversal of one layer occurred simultaneously with that of the other. The strength of exchange coupling was dependent on the thickness of non-magnetic spacer between the memory layer and the reference layer. It was found that the exchange coupling was blocked when the spacer was thicker than about 50 A. The existence of exchange coupling was also confirmed by domain writing experiments.