Study on lattice symmetry of sputtered Co-Cu-Pt metastable ordered thin films
Resource
Journal of Alloys and Compounds, 530, 18-21
Journal
Journal of Alloys and Compounds
Journal Issue
530
Pages
18-21
Date Issued
2012
Date
2012
Author(s)
Yuan, Fu-Te
Hsu, Jen-Hwa
Lin, Y.H.
Hsiao, S.N.
Lee, H.Y.
Abstract
The lattice symmetry and atomic stacking sequence of Cu-doped metastable L1 1 Co 50Pt 50 (Co 50-xCu xPt 50) films with thicknesses varied from 5 to 50 nm were examined by X-ray diffraction along the (10.1) diffraction rod. Replacement of Co with Cu significantly decreases the linewidth of the (1 1 1) superlattice diffraction peak, revealing reduced defect density. The crystal symmetry of CoPt L1 1 is identified as face-centered. After the addition of Cu (x ≥ 23), it evolves into rhombohedral, which is the thermodynamically equilibrium structure of CuPt. Furthermore, the decrease in film thickness results in the modification of structure in CoPt binary films, forming pseudo-hexagonal phase. As the film thickness is decreased from 10 to 5 nm, the component of pseudo-hexagonal phase increases from 7.1 vol.% to 13.6 vol.%. However, such a phase evolution disappears in the films with x = 23. The stabilization of rhombohedral L1 1 promotes the alignment of magnetic easy-axis, yielding a high perpendicular remanence ratio and negligible in-plane magnetic component, even in the 5 nm-thick sample. The presented results provide detailed information for the understanding of the relation between structure and magnetic properties of metastable CoPt-based L1 1 films. © 2012 Elsevier B.V. All rights reserved.
Type
journal article
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