Role of lattice matching in epitaxy: Novel Ce phase and new fcc-bcc epitaxial relationship.

We have grown a novel epitaxial phase of cerium on vanadium using molecular-beam epitaxy and characterized by high-energy electron and x-ray diffraction. The results show that the Ce phase is contracted by 8% in the basal plane and expanded 2% out of the plane when compared to the ambient-temperature and ambient-pressure fcc, y-Ce. Furthermore, the relative orientation of the Ce(111) and the V(110) planes is different from the well-known epitaxial relationships found to date experimentally and theoretically. The present results imply that electronic structure beyond simple geometrical lattice-matching considerations is important for epitaxial growth.