Exchange coupling, spin structure, and anisotropy properties in Co/Cr(001) superlattices

We have investigated by magneto-optic Kerr e#ect measurements the exchange coupling properties of Co/Cr(001) superlattices, which were grown by molecular beam epitaxial techniques. The Co thicknesses ranged from 5-30 A and the Cr thicknesses from 9-50 A. For Co thicknesses of about 10 A and Cr thicknesses below 14 A we observe an antiferromagnetic exchange coupling with near to perpendicular orientation of the Co magnetic moments. The remagnetization process in an external field can consistently be described by a surface spin-flip transition, followed by domain wall nucleation and motion. The saturation field has a maximum at a Cr thickness of about 6 A. Only one maximum of the exhange coupling is observable, which in position and shape is comparable to the exchange coupling in Fe/Cr superlattices. Antiferromagnetic exchange coupling also occurs for thicker Co layers and for magnetic moments oriented parallel to the film plane. The exchange coupling energies for parallel and perpendicu..