Evaporated Co/Pt layered structures for magneto-optical recording

The authors discuss the properties of thin (<500 Å) Co/Pt layered structures (LSs) or multilayers for magnetooptical recording. These LSs have a perpendicular magnetic anisotropy, part of which is attributed to an interface anisotropy contribution. LSs with Co layer thicknesses of 4 Å or less than Pt layer thicknesses of 10-20 Å thick have a 100% magnetic remanence and a Kerr rotation, θ_k, of -0.1° to -0.2° as well as optical reflectivity R=70%, both at λ=820 nm. The Curie temperature of these LSs is between 300 and 400°C. The authors also present the first disk performance data for Co/Pt LSs. A pregrooved disk was coated with AlN and a 23×(3.5 Å Co+13 Å Pt) LS, and, although the figure of merit Rθ²_k was not fully optimized, a carrier/noise ratio of 49 dB was achieved. This, together with the excellent magnetic properties and high oxidation resistance, makes these Co/Pt LSs very promising candidates for magnetooptical recording. Furthermore, θ_k increases at shorter wavelengths where still higher recording densities are possible