MAGNETIC-ANISOTROPY IN EPITAXIAL FCC CO CU (1 1 13)/

Magnetization behavior of ultrathin (3 ML) epitaxial Co(001) films on Cu(1 1 13) terraced surfaces was studied in situ using magneto-optic K err effect. The films show easy magnetization along the steps. Unusual hard axis Kerr loops (H perpendicular to the steps and in the surface plane) are observed near room temperature and evolve at higher temper ature (127-degrees-C) toward the soft magnetic behavior more typical o f the easy axis loops observed on the same films. A model is postulate d for the behavior that includes a fourfold in-plane anisotropy and a uniaxial in-plane anisotropy of possibly magnetoelastic (ME) or magnet ostatic (MS) origin.