Core restructuring for magnetic Fe55 icosahedral nanoparticles

We investigate magnetic and structural properties of Fe55 clusters from DFT calculations. Previous calculations indicate the existence of icosahedral clusters with two antiferromagnetic states with magnetic moments smaller than experimentally measured. In the present work, we find a rearrangement of the atoms of the core (the 13 saturated atoms) that tend to form a structure close to a cuboctahedron, preserving the icosahedral structure for the surface shell (the 42 surface atoms). The introduction of a Hubbard correction term leads for the most stable electronic state to a ferromagnetic state and a high magnetic moment in agreement to experiment.