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Fabrication and Study of the Structure and Magnetism of Rare-Earth Free Nanoclusters
Extensive search for new magnetic materials free of critical rare-earth elements or expensive platinum suitable for technology or energy-applications is one of the main factors driving today’s research in magnetism. Development of these new materials is often hindered by conventional bulk-synthesis techniques which result in phase mixtures or poor magnetic properties. This dissertation focuses on this problem by investigating an alternate approach to fabricate nanoclusters of magnetic materials using an inert-gas-condensation cluster-deposition method, and analyzing their potential for magnetic applications. Nanoclusters of hard-magnetic Zr2Co11 were studied which have relatively high magnetocrystalline anisotropy as required for permanent-magnet applications. The Zr2Co11 nanoclusters exhibit high coercivity at room temperature, high magnetization and a high-energy product of 16.6 MGOe. When combined with a soft Fe-Co phase, the energy product rises to 19.5 MGOe. In-situ magnetic alignment of these nanoclusters is also demonstrated, which enhances the remanent magnetization and energy product. Mn5Si 3 and Fe5Si3 nanoclusters also were studied and high surface spin polarization was demonstrated for these materials resulting in novel magnetism such as, high magnetization and Curie temperature at the nanoscale compared to bulk. These materials show lattice-matching with semiconductors and high spin-polarization, which suggest further studies of these nanoclusters in the context of spintronics as potential spin-injectors.
Das, Bhaskar, "Fabrication and Study of the Structure and Magnetism of Rare-Earth Free Nanoclusters" (2017). ETD collection for University of Nebraska - Lincoln. AAI10270078.