MBE-Grown Epitaxial Co/Cr Superlattices
AbstractA series of epitaxial Co/Cr superlattices has been grown by molecular beam epitaxy. The Cr is in a metastable hcp phase as confirmed by transmission electron microscopy, selected area diffraction, and reflection high energy electron diffraction. The Cr layers are 10Å thick in all samples while the Co layers are varied from 12Å to 40Å. The diffusion between Co and Cr is studied by SQUID magnetometry and indicates step-like interfaces in the best samples. Interfacial sharpness has also been found to be unusually sensitive to Co deposition rates, and in contrast with other superlattice systems, we find that sharper interfaces enhance parallel anisotropy. Hall effect measurements of the saturation field are within 10% of SQUID values. Magnetoresistance at 4.2K is only 1/3% which we believe is a consequence of the high density of states at the Fermi level of hcp Cr.