MAGNETIC-PROPERTIES OF RARE-EARTH CLUSTERS

We report results of Stern-Gerlach deflection experiments on terbium clusters, which resemble earlier results for gadolinium clusters. As in gadolinium, we observe two distinct behaviors: clusters that are superparamagnetic and clusters that are described by a locked-moment model. The magnetic behavior is highly size dependent. Certain clusters make a transition from locked-moment to superparamagnetic behavior with increasing temperature and, in this process, exhibit an intermediate behavior. Both superparamagnetic and locked-moment clusters have magnetic moments per atom well below the bulk value. We show that oxygen atoms attached to the clusters have little effect on the clusters' magnetic properties and are not responsible for the two distinct behaviors observed in rare earth clusters. We also present preliminary results from studies on dysprosium clusters.