Effects of Co/Sm Composition on the Ordered Phase Formation in Sm-Co Thin Films Grown on Cu(111) Single-Crystal Underlayers
Sm-Co thin films were prepared on Cu(111) single-crystal underlayers by changing the Sm composition from 12 to 35 at.% and the effects of Co/Sm composition on the ordered phase formation were investigated. The epitaxial SmCo5 thin films were obtained for all samples. The SmCo5 epitaxial layer grown on Cu underlayer has two different types of domains whose orientations are rotated around film normal by 30 degrees to each other. Cu atoms substitute a part of the Co sites in the SmCo5 structure, and an alloy compound of Sm(Co,Cu) 5 phase was formed for all samples. The Sm(Co,Cu)5 phase was more Cu enriched with increasing the Sm composition. The Cu atom diffusion into Sm-Co layer plays an important role in assisting the formation of Sm(Co,Cu)5 ordered phase.
Fabrication of Sm–Co films with perpendicular magnetic anisotropy
Sm-Co/Cu films were prepared to study effects of substrate temperature during the preparation of the Sm-Co layer T S Sm-Co . The X-ray diffraction lines from the Cu (1 I 1) plane and the SmCo 5 (0 0 1) planes were observed, which revealed that the Sm-Co/Cu film with the perpendicular magnetic anisotropy was obtained when the T S Sm-Co was higher than 300 C.
Nanostructures of Sm-Co on Cr thin films
The nanostructures of Sm-Co on Cr thin films prepared by dc magnetron sputtering were investigated by high resolution transmission electron microscopy (HRTEM) and diffraction techniques. HRTEM micrographs show that the crystallites in the Sm-Co films, as revealed by the lattice fringes, are distributed discontinuously in the matrix. The matrix is amorphous as indicated by the microdiffraction study. The size of the crystallites is in the range of 2/spl sim/5 nanometers. The volume fraction of the crystallites in the film decreases from 91% to 54% as the argon pressure is increased from 5 mTorr to 30 mTorr. Micrographs recorded in a bright field transmission electron microscope (TEM) with a defocus of a few micrometers reveal grain-like structures of about 25 nm in some but not all films. This grain-structure is found to be inherited from the Cr underlayer. >