We have investigated the stability, electronic, and magnetic properties of transition-metal-doped $M{\mathrm{B}}_n$ clusters ($M=\mathrm{Cr},\mathrm{Mn},\mathrm{Fe},\mathrm{Co},\mathrm{Ni}$, $n⩽7$) using first-principles density functional theory with generalized gradient approximation. The equilibrium structures of $M{\mathrm{B}}_n$ $(n⩽5)$ clusters can be obtained by directly adding $M$ atoms to the ${\mathrm{B}}_n$ clusters, while for $n=6$, hexagon or near-hexagon geometries with a boron atom at the center ring are regarded as the ground-state structures. $n=7$ marks the onset of three-dimensional geometries for $M{\mathrm{B}}_n$ clusters. According to the second-order energy differences, gaps between the highest occupied molecular orbital and lowest unoccupied molecular orbital and vertical ionization potentials, we can conclude that $\mathrm{Cr}{\mathrm{B}}_4$, $\mathrm{Cr}{\mathrm{B}}_7$, $\mathrm{Mn}{\mathrm{B}}_3$, $\mathrm{Fe}{\mathrm{B}}_3$, $\mathrm{Fe}{\mathrm{B}}_5$, $\mathrm{Fe}{\mathrm{B}}_7$, and $\mathrm{Co}{\mathrm{B}}_7$ possess relatively higher stabilities. The relative orientation between the magnetic moments of the $M$ atom and those of its neighboring B atoms mainly exhibits an antiferromagnetic alignment for $\mathrm{Cr}{\mathrm{B}}_n$, $\mathrm{Mn}{\mathrm{B}}_n$, and $\mathrm{Fe}{\mathrm{B}}_n$, while it mainly shows a ferromagnetic alignment for $\mathrm{Co}{\mathrm{B}}_n$ and $\mathrm{Ni}{\mathrm{B}}_n$ clusters.

• Received 14 April 2007

DOI:https://doi.org/10.1103/PhysRevA.75.063201