Structural, electronic, and magnetic properties of FexCoyNiz (x+y+z=13) clusters: A density-functional-theory study

• Published in: Journal of magnetism and magnetic materials Vol. 394; pp. 325 - 334
• Main Authors: Varas, Alejandro, Aguilera-Granja, F., Rogan, José, Kiwi, Miguel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2015
• Subjects: DFT calculations; Electronic properties; Structural properties; Transition metal clusters; Electronic properties; Transition metal clusters; DFT calculations; Structural properties
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2015.06.088

The ternary alloy FexCoyNiz nanoparticles are of interest in both theoretical and experimental aspects, particularly due to the possible technological applications and due to the novel structural and magnetic properties in the sub-nanometer region. Here we compute the structural parameters, chemical and magnetic properties of these 13 atom nanoclusters. To the best of our knowledge, this is the first time that such kind of calculation is performed for all the possible compositions of 13-atom ternary nanoclusters. We performed density-functional-theory (DFT) calculations, as implemented in the SIESTA code, for all the possible concentrations (i.e. all x,y and z-values). The seeds for the possible homotops are built using a semi-empirical Gupta potential, and these conformations are thereafter subject to reoptimization by means of the SIESTA code. Based on known results, we focus our attention on just two types of possible nanostructures: icosahedral and compact biplanar. We find that approximately half of the minimum energy conformations are icosahedral, and the other half are biplanar, with most interatomic distances smaller than the bulk values. The binding is strongest for the FeCo rich nanoclusters, and weakest for pristine Ni13. However, a set of highly stable structures, with layer-like ordering, were found close to the Ni-rich region. These nanoalloys are expected to be the most abundant ones in cluster-growth experiments. We conclude that the total magnetic moment varies smoothly over the full composition range, with the large Fe moment being quenched by the addition of Co and/or Ni. By alloying, the magnitude of the moments varies almost continuously, and thus allows for fine tuning magnetism by controlling the composition, which has implications for magnetic recording. •FexCoyNiz (x+y+z=13) nanoalloys are investigated for all x, y and z.•The large Fe magnetic moment is quenched by doping with Ni and/or Co.•First principles (DFT) methods are used.•Minimal energy, geometrical conformations, and other relevant properties are obtained.