Structural and oxidation properties of CoNi nanowires

Abstract: Nanocylinders made out of CoNi alloys offer interesting properties which are dependent onthe proportion of the constituent elements, the preparation methods and the thermalhistory of the sample. In the present paper we calculate the structural and electronicproperties of Co_1−xNi_x alloys atsubnanoscopic level. SIESTA program is used to relax the structures following standardprotocols. Relative positions of the minority atoms (Ni) are varied aiming to find thelowest energy configurations. It is found that Ni atoms minimize energy at surfacepositions mainly at the ends of the cylinders. The implications of this result in themagnetic properties of the systems are discussed. The work is continued to study theoxidation properties of the different possible surface compositions. It is found thatsurfaces of Ni are more resistant to oxidation than Co ones. The combination of the twoprevious results can lead to cylinders with high magnetic coercivity and relatively highresistance to oxidation. Graphical abstract: [Figure not available: see fulltext.]