O Šipr et al 2007 J. Phys.: Condens. Matter 19 446205 doi:10.1088/0953-8984/19/44/446205
O Šipr1, S Polesya2, J Minár2 and H Ebert2
Show affiliationsWe investigate how temperature affects the dependence of the average magnetic moments
of clusters on their size and how the magnetic moment profile of an individual cluster varies with temperature T. The focus is on free spherical Fe clusters of 9–89 atoms. The interaction among individual magnetic moments is described by a classical Heisenberg spin Hamiltonian, with exchange coupling constants provided by ab initio calculations. Average magnetic moments
for finite T were obtained via Monte Carlo simulations. We found that the exchange coupling depends on the cluster size and on the position of the atom in the cluster in a complex way, with no obvious systematics. The magnetic moment profile of an individual cluster becomes more uniform if T increases. The dependence of
on the cluster size, in practice, does not depend on temperature if T is in the range of 0–300 K. Ground-state calculations for T = 0 K should thus be able to describe experiments based on the deflection of a molecular beam in a magnet for
K.
75.30.Cr Saturation moments and magnetic susceptibilities
75.10.Dg Crystal-field theory and spin Hamiltonians
Issue 44 (7 November 2007)
Received 27 April 2007, in final form 5 September 2007
Published 16 October 2007
O Šipr et al 2007 J. Phys.: Condens. Matter 19 446205
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