Molecular-beam-epitaxy growth and structural characterization of high-quality single-crystal Co/Cr(001) superlattices

Abstract

High-quality single-crystal Co/Cr(001) superlattices with layer thicknesses of 5--50 A\r{} have been grown by molecular-beam epitaxy. In contrast to other investigations we found that hcp Co grows with its (11.0) plane parallel to Cr(001). The Co layers exhibit a remarkable expansion of \ensuremath{\approxeq}6% perpendicular to the film plane, indicating a structural change in direction to the bcc phase. However, in-plane diffraction experiments confirmed that the hexagonal symmetry remains for Co layer thicknesses down to 4 A\r{}.