Preparation of hcp-NiFe $(11\bar{2}0)$ Thin Films on Au(100) Underlayers

NiFe epitaxial thin films with hcp structure were obtained on Au(100) single-crystal underlayers formed on MgO(100) at substrate temperatures lower than 400°C by molecular beam epitaxy. The structural and the magnetic properties of hcp-NiFe thin films were investigated. Reflection high energy electron diffraction and X-ray diffraction analyses indicate that the metastable hcp-NiFe crystal tends to transform into more stable fee crystal during film growth process. With increasing the substrate temperature, the volume ratio of hcp crystal decreases, whereas that of fee crystal increases. The NiFe film prepared at 100°C consists primarily of hcp crystal with the (112¿0) plane parallel to the substrate surface co-existing with very small amount of fcc-NiFe(100) crystal. The lattice parameters of hcp-NiFe crystal are determined as a = 0.251 nm, c = 0.405 ± 0.002 nm, and c/a = 1.61 ± 0.01.