MAGNETIC FORCE MICROSCOPY OF CO-PD MULTILAYERS WITH PERPENDICULAR ANISOTROPY

The domain structure of sputtered Co-Pd multilayer films of varying thickness has been investigated by magnetic force microscopy. The domains appear as stripe domains, typical of perpendicularly oriented films. The size of the domains was strongly influenced by the thickness of the film. The domain repetition lengths give an additional experimental parameter which has been used to provide a stronger test of a theoretical model developed for ferromagnetic multilayer films [H. J. G. Draaisma and W. J. M. de Jonge, J. Appl. Phys. 62, 3318 (1987)]. It is found that the experiment and theory are broadly in agreement provided that the increased magnetization of the multilayer caused by polarization of the Pd is accounted for. There is a noticeable difference between the variation of the measured and theoretical domain repetition lengths with film thickness. This is attributed to the effects of domain-wall pinning which is not considered in the model. It is estimated that the characteristic length of the films is 55 angstrom and the domain-wall-energy is 14 mJ/m2.