Eur. Phys. J. D 64, 53-62 (2011)
https://doi.org/10.1140/epjd/e2011-20178-0

Regular Article

Structural and magnetic properties of Fe_mY_n (m + n = 7, Y = Ru, Rh, Pd, and Pt) nanoalloys

¹ Instituto de Física “Manuel Sandoval Vallarta”, Universidad Autónoma de San Luis Potosí, Alvaro Obregón 64, 78000 San Luis Potosí, México
² Facultad de Ciencias, Universidad Nacional Autónoma de México, México

^a e-mail: jmmc@dec1.ifisica.uaslp.mx

Received: 24 March 2011
Received in final form: 2 June 2011
Published online: 29 July 2011

Abstract

The structural and magnetic properties of the small binary clusters Fe_mY_n (with m + n = 7, Y = Ru, Rh, Pd, Pt) were studied through extensive ab initio calculations, by means of the fully unconstrained version of the density-functional method, as implemented in the SIESTA code, within the generalized gradient approximation. The lowest energy state geometries, the chemical ordering, and the electronic and the magnetic structures were calculated. We found that the lowest energy geometrical structures for the pure Ru, Rh, Pd, Pt, and Fe heptamers, are a cube without an apex, a triangular prism capped on a square face, a decahedron, a side capped double square, and a decahedron, respectively. Starting from these geometries of the pure element heptamers, we followed the changes in the geometric structure as a function of the chemical composition. We analyzed all the different chemical arrangements, which depend on the particular geometry, and magnetic moment orientations, in the whole range of compositions. In general, there are important modifications to the magnetic moment of the Y atoms as soon as one of them is substituted by an Fe atom in the cluster. In contrast, under the same circumstances, the Fe magnetic moment takes values larger than 3 μ_B and keeps almost this value, insensitive to the structure, composition and chemical order of the system.