Effect of Substrate Temperature on the Ordered Phase Formation in Sm–Ni Thin Film Deposited on Cu(111) Underlayer

摘要

${hbox{Sm}}_{17}{hbox{Ni}}_{83}$ (at.%) alloy thin films are prepared on Cu underlayers hetero-epitaxially grown on MgO(111) single-crystal substrates by employing an ultra-high vacuum molecular beam epitaxy system. The substrate temperature is varied from 100 $^ circ{hbox{C}}$ to 500 $^ circ{hbox{C}}$ . The film growth behavior and the detailed resulting film structure are respectively investigated by in situ reflection high-energy electron diffraction and by a combination of out-of-plane and in-plane X-ray diffractions. With increasing the temperature up to 300 $^ circ{hbox{C}}$, formation of ordered ${hbox{SmNi}}_{5}$ phase is recognized. The films deposited above 400 $^ circ{hbox{C}}$ consist of only epitaxial ${hbox{SmNi}}_{5} (0001)$ crystal, whereas the films deposited below the temperature include amorphous phase and/or a hexagonal ordered phase other than ${hbox{SmNi}}_{5}$. When the temperature is increased from 300 $^ circ{hbox{C}}$ to 500 $^ circ{hbox{C}}$, the long-range order degree of ${hbox{SmNi}}_{5}$ film increases from 0.60 to 0.97. ${hbox{SmNi}}_{5}$ phase formation is enhanced with increasing the temperature.