Magnetic Structure of Free Cobalt Clusters

We have studied the magnetic properties of free cobalt clusters in two semi-independent Stern-Gerlach deflection experiments at temperatures between 60 and 307 K. We find that clusters consisting of 13 to 200 cobalt atoms exhibit behavior that is entirely consistent with superparamagnetism, though complicated by finite-system fluctuations in cluster temperature. Based on their superparamagnetic behavior, we report magnetic moments per atom for each cobalt cluster size and compare the results of our two measurements and those performed previously