  We performed ab initio calculation on the pristine and carbon-doped (5,5) and
(9,0) BN nanotubes. It was found that Carbon substitution for either boron or
nitrogen in BN nanotubes can induce spontaneous magnetization. Calculations
based on density functional theory with the local-spin-density-approximation on
the electronic band structure revealed a spin polarized, dispersionless band
near the Fermi energy. The magnetization can be attributed to the carbon 2p
electron. Compared to other theoretical models of light-element or metal-free
magnetic materials, the Carbon-doped BN nanotubes are more experimentally
accessible and can be potentially useful.
