Magnetic materials have received widespread interest due to potential applications in fields ranging from biomedicine to data storage. Nanoparticles are known to support size dependent (d = 1 – 3 nm) per atom magnetic moments that are higher than their bulk counterparts, making them promising platforms to build high performance magnetic systems. However, the ligand shells required to stabilize these particles may also quench their magnetic properties. Here, we use density functional theory to study the size dependent magnetism of ligand-passivated Co nanoclusters ranging from 13 to 92 metal atoms.  Overall, we find that the local coordination environment of individual Co atoms encompasses both the composition of the first coordination sphere as well as long-range structural motifs. Both these local and extended coordination environments contribute strongly to the local magnetic moment of a given Co atom in these clusters. Therefore, linear size-dependent trends are not observed. Instead, this collection of individual coordination environments is informed by, but not comprehensively defined by, nanocluster size, and is also strongly dependent on core symmetry, ligand density, and ligand arrangement. Taken together, these results indicate that developing synthetic methods to access the structural complexity possible at the nanoscale would allow unprecedented magnetic behaviors to be studied, targeted, and realized.

Ligand mediated evolution of size dependent magnetism in cobalt nanoclusters

254th National Meeting (2017)

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