B and C doped Cuboctohedral Mn$_{13}$ Clusters with Giant Magnetic Moments

Using first-principles calculations based on gradient corrected density functional theory we show that an otherwise distorted icosahedric Mn$_{13}$ ferrimagnetic cluster, when doped with six B or C atoms, transforms into a ferromagnetic cuboctahedral cluster with a magnetic moment that is an order of magnitude larger than that of the pure Mn$_{13}$ cluster. The origin of this magnetic transition is attributed to the change in the Mn-Mn interatomic distance resulting from the structural transformation. These doped clusters remain ferromagnetic with giant moments even after removing a B or C atom. However, similar doping with N atom does not lead to ferromagnetic ordering and Mn$_{13}$N$_{6}$ remains ferrimagnetic with a magnetic moment of only 3 $\mu_{\mathrm{B}}$, just as in its parent Mn$_{13}$ cluster.