Study on lattice symmetry of sputtered Co-Cu-Pt metastable ordered thin films

JOURNAL OF ALLOYS AND COMPOUNDS

卷:530

Article

Yuan, Fu-Te¹  Hsu, Jen-Hwa¹  Lin, Y. H.²  Hsiao, S. N.³  Lee, H. Y.³ 

[1] Natl Taiwan Univ, Dept Phys, Taipei 106, Taiwan

[2] Natl Taiwan Univ, Dept Mat Sci & Engn, Taipei 106, Taiwan

[3] NSRRC, Hsinchu 300, Taiwan

关键词: Magnetic films and multilayers;    Metals and alloys;    Vapor deposition;    Anisotropy;    X-ray diffraction;    Magnetic measurements;   

DOI  :  10.1016/j.jallcom.2012.03.086

来源: Elsevier

【 摘 要 】

The lattice symmetry and atomic stacking sequence of Cu-doped metastable L1(1)Co(50)Pt(50) (Co50-xCuxPt50) 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. (C) 2012 Elsevier B.V. All rights reserved.

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