Magnetic Properties of Cobalt and Chromium Clusters

Payne, Forrest William, Department of Physics, University of Virginia
Bloomfield, Lou, Department of Physics, University of Virginia
Fowler, Michael, Department of Physics, University of Virginia
Howe, James, Department of Materials Science and Engineering, University of Virginia

We have used the Stern-Gerlach deflection technique to study magnetism in cobalt clusters of 13-187 atoms and chromium clusters with between 20-133 atoms. These clusters were observed at temperatures ranging from 60K to 250K and at magnetic field gradients up to 360 T/m. Using superparamagnetic theory we have determined the moment per atom for each cluster size and find enhanced magnetism due to reduced dimensionality of the clusters. Remarkably, we find that we are capable of making chromium clusters in two magnetically distinguishable forms for each cluster size with ≥ 34 atoms. We attribute this observation to the presence of structural isomers. To my lovely wife Mary, and To Aubin and Rayla.

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PHD (Doctor of Philosophy)
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