MAGNETIC-PROPERTIES OF RARE-EARTH CLUSTERS

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