Electronic and magnetic properties of NiPd and CoPd nanostructures
J. Guevaraa,b, A.M. Lloisb,c, F. Aguilera–Granjad, and J.M. Montejano–Carrizalesd,*
ª Escuela de Ciencia y Tecnología, Universidad de San Martín, Campus Miguelete – Edificio Tornavias, Martín de Irigoyen 3100, (1650) San Martín, Argentina.
b Departamento de Física, CAC–CNEA, Avda. Gral. Paz 1499, (1650) San Martín, Argentina.
c Departamento de Física, FCEyN–UBA, Cdad. Universitaria, 1428 Buenos Aires, Argentina,
d Instituto de Física, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México, *e–mail: jmmc@ifisica.uaslp.mx
]]>Recibido el 16 de junio de 2009
Aceptado el 13 de enero de 2010
Abstract
We study the dependence of the magnetic properties of NiPd and CoPd segregated nanoclusters and slabs as a function of the 3d magnetic component concentration (x), the chemical order, and size. In the case of clusters we consider 3d cores coated by Pd atoms (3d/Pd) and also onion–like (Pd/3d/Pd) configurations. For the slabs we consider different possible segregated structures of the 3d and 4d atoms and study the evolution of the magnetic properties on these different configurations. We show that Pd coating gives rise to an enhancement of the average magnetic moment of the Ni or Co core atoms and of the Pd atoms as well. Larger values of the average magnetic moments are obtained in the onion–like structures (Pd/3d/Pd) than in the core/shell (3d/Pd) configuration. We compare with theoretical and experimental results available in the literature.
Keywords: Bimetallic cluster; magnetic properties; nanostructures; work function.
Resumen
Se estudia la dependencia de las propiedades magnéticas de nanocúmulos segregados y películas de NiPd y CoPd como función de la concentración de la componente magnética 3d (x), del orden químico y del tamaño. En el caso de los cúmulos, se consideran núcleos 3d cubiertos por átomos Pd (3d/Pd) y también configuraciones por capas tipo cebolla (Pd/3d/Pd). Para las películas se consideran diferentes posibles estructuras segregadas de los átomos 3d y 4d y se estudia la evolución de las propiedades magnéticas de las diferentes configuraciones. Se muestra que la cubierta de Pd da lugar a un incremento del momento magnético promedio de los átomos del núcleo de Ni o Co así como de los átomos de Pd también. Se obtienen valores más grandes de los momentos magnéticos promedio en las estructuras por capas (Pd/3d/Pd) que en las configuraciones núcleo/cubierta (3d/Pt). Se compara con resultados experimentales disponibles en la literatura.
]]> Descriptores: Cúmulos bimetálicos; propiedades magnéticas; nanoestructuras; función de trabajo.
PACS: 75.75.+a; 36.40.Cg; 75.50.–y
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Acknowledgments
Javier Guevara and Ana María Llois are also researchers of CONICET We acknowledge PICT 03–10698 of Agencia Nacional de Promoción Científica y Tecnológica, PIP 6016 of CONICET, Grant SA06/070 of UNSAM, for partial support. This work was partially funded by the PROMEP–SEPCA–16–2007–24–21, México. Also JMMC and FAG acknowledge the financial support from CONACyT (México) through grants No. 50650. Computer resources from the Centro Nacional de Supercómputo (CNS) from the Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), San Luis Potosí, México, is also acknowledged. We also wish to thank J. Limón–Castillo for computational assistance.
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