INFLUENCE OF STRUCTURE ON THE MAGNETIC-ANISOTROPY OF CO/PD (001) EPITAXIAL SUPERLATTICES

We have used molecular beam epitaxy to grow Co/Pd superlattices oriented along the fcc [001] crystal direction. A series of samples of fixed Pd thickness (t(Pd) = 9 +/- 1 angstrom) and varying Co thickness (2 less-than-or-equal-to t(Co) less-than-or-equal-to 8 angstrom) was prepared. The uniaxial magnetic anisotropy in these films displayed both a large perpendicular interface contribution and a large in-plane volume contribution. Using off-axial X-ray diffraction techniques to measure the fcc (113) Bragg reflection, the in-plane lattice spacing of three samples was directly measured. These measurements are consistent with a coherent strain model with the Co layers expanded in-plane by 8.0% +/- 0.5% over that of bulk fcc Co. An estimate of the in-plane magnetoelastic energy calculated from this strain is in very good agreement with our observed volume anisotropy in these superlattices.