Magnetic and Magneto-Optical Properties of Co/Ru Multilayers

The magnetic and magnetooptic properties of Co/Ru, Co/Au and Co/Pd multilayered films were investigated. Perpendicular magnetic anisotropy was found in the Co/Ru system. The anisotropy was enhanced by adopting a Pd base layer to improve the film periodicity and crystallinity. Co/Ru multilayer films with Co layer thicknesses under 18 Å can be easily magnetized perpendicular to the film plane. As the Co layer thickness decreases, the saturation magnetization per unit volume Co decreases in the Co/Ru and Co/Au systems, but increases in the Cq/Pd system. The Co/Ru films exhibited small remanent magnetizations and coercive forces of a few hundred Oe. Despite the differences in the nonmagnetic metal layers of the three systems, the surface anisotropy energies are almost equal. The difference in the volume anisotropy energy is due to the demagnetization energy. The magnetooptic effect of Co/Ru multilayered film declines at short wavelengths.