Electronic structures and spin gapless semiconductors in BN nanoribbons with vacancies

One distinct class of band structures, spin gapless semiconductors in which both electrons and holes can be fully spin polarized, has been proposed recently [X. L. Wang, Phys. Rev. Lett. 100, 156404 (2008)]. Exotic spin-related phenomena and potential applications were predicted for those semiconductors. In the present work, the electronic structures of BN nanoribbons are studied from ab initio calculations. Two kinds of spin gapless semiconductors are predicted in the nanoribbons with certain B or N vacancies. The unique bands are found to be independent of the width of the nanoribbons. The appearance of the spin-polarized bands in BN system without traditional magnetic ions is ascribed to dangling-bond states formed near the vacancies. The magnetism induced by B vacancies is found to be stronger than that by N. The magnetism can be understood well through Stoner rule.