Square-loop cobalt/gold multilayers

Multilayers of Co and Au with perpendicular hysteresis loop squareness ratios of ∼1 have been prepared by e-beam evaporation. These films have perpendicular anisotropy in the as-deposited condition in contrast to other work in which Co/Au multilayers, prepared by ion beam sputtering, showed perpendicular anisotropy only after annealing at 300°C. The Faraday rotation of these square-loop multilayers is about 9×105 deg/cm of Co or 1×105 deg/cm of total thickness at a wavelength of 633 nm. These values indicate an enhancement of the Faraday rotation of Co at this wavelength by about a factor of 2. This may be a plasma-edge enhancement effect similar to that reported by Katayama et al. [Phys. Rev. Lett. 60, 1426 (1988)] in the Kerr effect of Fe/Au multilayers.