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

Abstract

  Sm_xNi_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 (1120) epitaxial crystals with RT₅-type structure. The epitaxial films involve two types of (1120) 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.