Molecular-Beam Epitaxial Growth and Structures of Dy on (100) and (211)Cr Thin Films

Abstract

We studied the crystal growth and structures of hexagonal close-packed Dy layers grown on body-centered cubic (100) and (211)Cr thin films using molecular-beam epitaxy. The (100) and (211)Cr films with smooth surfaces were prepared by growing Cr on (100) and (110)MgO substrates, respectively. The Dy layers were grown on these Cr thin films. During growth, surface structures were monitored by reflection high-energy electron diffraction. After growth, X-ray diffractometry was performed to analyze film structures. We found that Dy layers grow epitaxially on (100)Cr at 50 °C with two types of predominant domain: Dy(0001)[2110] ∥ Cr(100)[001] and Dy(0001)[0110] ∥ Cr(100)[001]. We also found that (1012)Dy grows epitaxially at 50 °C on (211)Cr with a tilt of approximately 3.7°. The orientational relationship is tilted-Dy(1012)[1210] ∥ Cr(211)[111]. These orientational relationships were discussed in connection with crystal structures and geometrical relationships. We show that the observed orientational relationships can be successfully explained in terms of strain with the aid of geometrical consideration.