Growth of rare-earth single crystals by molecular beam epitaxy: The epitaxial relationship between hcp rare earth and bcc niobium

Abstract

High-quality rare-earth (RE) single-crystal films of yttrium (Y) and gadolinium (Gd) were successfully grown with the metal molecular beam epitaxy technique on a bcc Nb single-crystal film which serves as a buffer layer to the sapphire substrates. With reflection high-energy electron diffraction, the hcp RE (0001) was found to grow epitaxially on the (110) Nb in the Nishiyama–Wasserman orientation. The regrowth of Nb on this RE (0001) surface yielded the (110) orientation with 120° in-plane domains. These epitaxial relationships suggest the possibility of fabricating an ultrathin, coherent crystalline superlattice in the Nb (110)/ RE (0001) system.