Nanomaterials and Nanotechnologies

The effects of nitrogen on the configurations and magnetic moments of small iron, cobalt and nickel clusters

H.-Y. Zhao^a1, J. Wang^a1a2, Y. Liu^a1a2 and Y.-C. Li^a1

Department of Physics, and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Shijiazhuang 050016, Hebei, P.R. China

National Key Laboratory for Materials Simulation and Design, Beijing 100083, P.R. China

Abstract

The configurations, electronic structures and magnetic properties for M _n N clusters (M = Fe, Co, Ni; n = 2−12, 14, 18) are obtained using all-electron density functional theory calculations at the general gradient approximation level. On doping an N atom into the pure M _n clusters, the ground-state structures, binding energies of the resulting mixed clusters have changed but the average M–M bond length does not obviously change except for Fe₂N, Co₇N and Ni₇N. The doping N atom prefers surface sites except for n = 14 and 18. The results also show the enhanced stability for M _n N clusters compared with that of the corresponding pure M _n clusters. The large energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for Fe _n N (n = 6,12), Co _n N (n = 3,5,7,9,11) and Ni _n N (n = 3,6,11,14) clusters indicate their high chemical inertness. Moreover, it has also been found that the total spin magnetic moments of all the M atoms increase slightly for: M = Fe, n = 9,12,14; M = Co, n = 8,9,11,18; and M = Ni, n = 3,11,12.

(Received February 16 2009)

(Accepted July 3 2009)

(Online publication November 4 2009)

PACS:

• 36.40.-c – Atomic and molecular clusters;
• 36.40.Cg – Electronic and magnetic properties of clusters;
• 61.46.-w – Structure of nanoscale materials

yliu@hebtu.edu.cn