Magnetic properties of spherical fcc clusters with radial surface anisotropy

We have studied the magnetic properties of spherical fcc clusters at zero temperature using a numerical solution of the Landau-Lifshitz equations of motion with damping. Of particular interest is the effect caused by anisotropy which is uniaxial, radial, and present only on the surface. The hysteresis curves are obtained for different values of the anisotropy strength and for different cluster sizes. Insight into the spin-field configurations close to reversal is given. A specific dependence of the coercivity on the size of the clusters is found, which is explained qualitatively by the relative weight of the surface sites in the total number of sites in the cluster.