MOLECULAR-BEAM-EPITAXY GROWTH AND STRUCTURAL CHARACTERIZATION OF HIGH-QUALITY SINGLE-CRYSTAL CO/CR(001) SUPERLATTICES

High-quality single-crystal Co/Cr(001) superlattices with layer thicknesses of 5-50 angstrom 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 almost-equal-to 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 angstrom.