Eur. Phys. J. B 37, 177-185 (2004)
https://doi.org/10.1140/epjb/e2004-00044-x

Magnetization and configurational anisotropy in magnetic clusters: Monte Carlo simulation

¹ National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, P.R. China
² Department of Physics, Fujian Normal University, Fuzhou, 350007, P.R. China

Corresponding author: ^a zghuang@fjnu.edu.cn

Received: 31 May 2003
Revised: 10 September 2003
Published online: 15 March 2004

Abstract

Based on the Monte Carlo simulation, the magnetic properties of the clusters, e.g. magnetization, Curie temperature, hysteresis, coercivity, natural angle and energy distribution etc., have been calculated. It has been found that, for the pure ferromagnetic cluster, the Bloch law is well satisfied at low temperature () and B_sur is equal to . Meanwhile, there are clear indications that B increases drastically with the reducing atomic number N which is consistent with the experimental facts. The results have been evalucted using the Bloch exponent law in the approximate crystalline approximation. It has also been demonstrated that the size dependence of the Curie temperature can be described by finite-size scaling theory. The investigation of the hysteresis and the spin configurations in different magnetization processes reveals the existence of an easy magnetization direction and anisotropy. The thermal coercivity for the clusters with zero and finite uniaxial anisotropy matches the experimental results well. The simulated results for the natural angle and energy distribution in the clusters prove further the existence of the configurational anisotropy in the clusters. It has been discussed that the natural angle and energy distribution influence the hysteresis of a cluster.