Structural transition in epitaxial Co-Cr superlattices

Using a real-time reflection high-energy electron diffraction analysis technique, we show that the epitaxial growth of Co-Cr superlattices incorporates coherent close-packed Cr layers up to a thickness of 6 A{}. Beyond this thickness there is an abrupt structural transition to bcc (110) Cr in the classic Nishiyama-Wasserman and Kurdjumov-Sachs orientations. Magnetization and magnetoresistance results indicate that interlayer coupling is very weak, which we attribute to the altered crystal structure in the Cr layers.