Anisotropies and magnetostriction constants of epitaxial Co films on GaAs(100) substrates

Metastable body centred cubic (bcc) Co has been grown as an epitaxial thin film on GaAs, using molecular beam epitaxy. In this paper, epitaxial Co films were grown on GaAs(100) substrates with 1 x 1 surface construction. The film thicknesses cover the bcc-hcp (hexagonal close packed) Co transition. The magnitudes and symmetries of the anisotropy for these films were estimated from normalized magnetization data measured using a magneto-optic Kerr effect magnetometer. It was determined for these films that there was an early onset of the hcp phase and of the uniaxial anisotropy component. The magnetostriction constants were determined by straining the films over a series of bend radii and determining the change in the anisotropy field (the Villari effect). The large uniaxial anisotropy observed in one case may be ascribed to a large magnetostriction constant for that film.