Coordination-driven magnetic-to-nonmagnetic transition in manganese-doped silicon clusters

The interaction of a single manganese impurity with silicon is analyzed in a combined experimental and theoretical study of the electronic, magnetic, and structural properties of manganese-doped silicon clusters. The structural transition from exohedral to endohedral doping coincides with 3d electron delocalization and a quenching of high-spin states. For all geometric structures investigated, we find a correlation of the magnetic moment with the manganese coordination number and nearest-neighbor distance. This observation can be generalized to manganese point defects in bulk silicon, whose magnetic moments fall within the observed magnetic-to-nonmagnetic transition, and therefore react very sensitively to changes in the local geometry. The results indicate that high-spin states in manganese-doped silicon could be stabilized by an appropriate lattice expansion.