First-principles study of silicon-doped (5,5) BN nanotubes

An ab initio calculation on the pristine and silicon-doped (5,5) boron nitride nanotube was performed. It was found that the silicon substitution for either a single boron or a single nitrogen atom in the (5,5) BN nanotube can induce spontaneous magnetization, and the local symmetry of the system is broken by the silicon atom extending outward of the tube. Calculations based on the density functional theory with the local spin density approximation on the electronic band structure revealed a spin-polarized, dispersionless p band near the Fermi energy. The magnetization can be attributed to the 3p unpaired electron of silicon. Compared to other theoretical models of light-element or metal-free magnetic materials, the silicon-doped (5,5) BN nanotubes are more experimentally accessible and can be potentially useful.