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

We have investigated by magneto-optic Kerr effect 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 Å and the Cr thicknesses from 9-50 Å. For Co thicknesses of about 10 Å and Cr thicknesses below 14 Å 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 Å. 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 perpendicular spin orientation are roughly the same. We have also determined the temperature dependence of the saturation field and the magnetic anisotropy for thin Co layer thickness from 10 to 40 Å. We