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Phys. Rev. Lett. 90, 026105 (2003) [4 pages]

Antisite-Defect-Induced Surface Segregation in Ordered NiPt Alloy

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L. V. Pourovskii1, A. V. Ruban2, B. Johansson1,3, and I. A. Abrikosov1
1Condensed Matter Theory Group, Physics Department, Uppsala University, Box-530, S-75121 Uppsala, Sweden
2Center for Atomic-scale Materials Physics and Physics Department, Technical University of Denmark, DK-2800 Lyngby, Denmark
3Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Received 6 March 2002; published 17 January 2003

By means of first principles simulations we demonstrate that tiny deviations from stoichiometry in the bulk composition of the NiPt-L10 ordered alloy have a great impact on the atomic configuration of the (111) surface. We predict that at T=600  K the (111) surface of the Ni51Pt49 and Ni50Pt50 alloys corresponds to the (111) truncation of the bulk L10 ordered structure. However, the (111) surface of the nickel deficient Ni49Pt51 alloy is strongly enriched by Pt and should exhibit the pattern of the 2×2 structure. Such a drastic change in the segregation behavior is due to the presence of different antisite defects in the Ni- and Pt-rich alloys and is a manifestation of the so-called off-stoichiometric effect.

© 2003 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.90.026105
DOI:
10.1103/PhysRevLett.90.026105
PACS:
68.35.Dv, 68.35.Md, 68.47.De
 
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