From Tiny Magnetic Clusters to Functional Magnetic Materials
Magnetic nanoparticles have been of continuous interest, in part, because of the surface effects on the magnetic properties and, in particular, because of their possible use in future magnetic storage devices. In this contribution we discuss the results of ab initio calculations for tiny magnetic transition metal clusters up to ∼ 103 atoms and show the variation of the magnetic moments and magnetic anisotropy as a function of the cluster size, morphology and kind of transition metal atoms. Since the ab initio calculations show that the magnetic moments of the clusters have rather localized character, we have also considered quantum Heisenberg models of spin‐1∕2 and spin‐1 clusters. The exact diagonalization of these models provide some supplementary informations to the first‐principles calculations regarding correlation functions and thermodynamic properties.
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