Fabrication and structure of Co/Cu artificial superlattices.

Highly oriented Co/Cu artificial superlattices were prepared using UHV deposition technique. In situ observation of RHEED patterns was made during the fabrication process. The Co/Cu superlattices were grown at relatively low temperature (50°C) onto Si(111) single crystal substrates with Ag(l11) buffer layers. The thickness of each layer was varied from 8 to 33Å. From RHEED patterns it was confirmed that the surfaces of both Co and Cu layers were atomically flat. X-ray measurements showed that all the samples had a compositionally modulated structure, and both Co and Cu layers had fcc structure with coherent interfaces when Co layers were thinner than 16Å. The Co/Cu superlattices were essentially single crystals containing stacking faults and twin faults. The Co-Cu system is considered to be one of the desirable ones in preparing superlattices with sharp interfaces.