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| Title: | BUILDING HIGH PERFORMANCE MAGNETIC MATERIALS OUT OF GAS PHASE NANOCLUSTERS | |
| DOI No: | 10.1142/9789812701879_0025 | |
| Source: | CLUSTERS AND NANO-ASSEMBLIES (pp 205-222) | |
| Author(s): | C. BINNS
Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK S. H. BAKER Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK S. LOUCH Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK S. C. THORNTON Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK |
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| Abstract: | It has been known for over a decade that free magnetic nanoclusters display novel properties including enhanced magnetic moments in ferromagnetic metals, ferrimagnetism in antiferromagnetic metals and the appearance of magnetism in non-magnetic metals. A contemporary challenge is to build intrinsic novel behaviour into macroscopic materials. We have investigated the magnetic behaviour of supported Fe and Co nanoclusters from the simplest possible system of isolated clusters adsorbed on substrates in UHV to dense interacting assemblies. XMCD measurements of exposed mass-selected Fe clusters in the size range 180-700 atoms deposited in situ onto HOPG substrates reveal enhancements in both orbital and spin moments relative to the bulk. Increasing the surface density of Fe clusters to induce a significant interaction however reduces the orbital moment to its small bulk value. Coating the exposed Fe clusters with Co increases the spin moment still further without significantly changing the orbital moment. The anisotropy in isolated Fe and Co clusters embedded in Ag matrices is uniaxial with the anisotropy axes randomly oriented in three dimensions. Thick cluster films adopt a domainless correlated super-spin glass magnetic configuration resulting from the frustration between the inter-cluster exchange coupling and random anisotropy. This state is magnetically soft, which is a useful attribute in high-moment films. | |
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