Strain-induced perpendicular magnetic anisotropy of 〈100〉-oriented Ni-Cu superlattices

The uniaxial perpendicular and magnetocrystalline anisotropies in strained 〈100〉-oriented Ni-Cu superlattices have been determined by in-plane and out-of-plane ferromagnetic resonance and magnetization measurements for varying Ni and Cu thicknesses. X-ray-diffraction patterns of the superlattice structure for these films indicate that the Ni lattice contracts while the Cu lattice dilates along the growth direction. Utilizing the measured strain with known elastic and magnetostriction constants for bulk Ni, the calculated strain-induced magnetoelastic anisotropies due to an inverse magnetostriction are in good quantitative agreement with the experimentally determined uniaxial perpendicular anisotropies.