Preparation and Structure Characterization of Sm-Ni Alloy Epitaxial Thin Films

Abstract

Sm x Ni 100-x (at. %) alloy thin films are prepared on Cr(100) underlayers hetero-epitaxially grown on MgO(100) single-crystal substrates at 500 °C by employing an ultra-high vacuum molecular beam epitaxy system with varying the Sm content from Ni-rich to Sm-rich region (x = 10-25 at. %) including the SmNi5 stoichiometry. The influence of film composition on ordered phase formation is studied by reflection high-energy electron diffraction and X-ray diffraction. Sm-Ni films with Sm compositions between 13 and 17 at. % consist of (112 _ 0) epitaxial crystals with RT5-type structure. The epitaxial films involve two types of (112 _ 0) variant whose c-axes are lying in the film plane and rotated around the film normal by 90° each other. As the Sm content departs from the compositional range, an amorphous phase tends to be included in the film in addition to SmNi5 ordered phase.