ROTATIONAL EFFECTS ON THE MAGNETIC-PROPERTIES OF AN ENSEMBLE OF FREE METAL-CLUSTERS

The magnetization of an ensemble of free magnetic metal clusters in an inhomogeneous external magnet field is calculated. In particular we have investigated the effects of the combined lattice anisotropy and cluster rotation on the magnetic properties. If weak anisotropy is present, almost superparamagnetic behavior is obtained. For stronger anisotropies deviations from this are calculated as a consequence of spin resonance due to the anisotropy field and the cluster rotation. This was proposed recently by de Heer et al. to explain his experimental data as generally expected, since a rotating cluster in a static magnetic field should behave similarly than a nonrotating one in an oscillating magnetic field. The magnetization depends also sensitively on the relaxation times.