  Using density functional theory, we predict half-metallicity in edge
hydrogenated armchair boron nitride nanoribbons (ABNNRs). The predicted spin
polarization is analyzed in detail by calculating electronic and magnetic
properties of these hydrogenated ABNNRs by means of first-principles
calculations within the local spin-density approximation (LSDA). ABNNRs with
only edge B atoms passivated by H atoms are found to be half-metallic
(regardless of their width) with a half-metal gap of 0.26 eV. Upto 100% spin
polarized charge transport is predicted across the Fermi level owing to the
giant spin splitting. Transmission spectrum analysis also confirms the
separation of spin up and spindown electronic channels. It is revealed that
H-passivation of only edge N atoms transforms non-magnetic bare ribbons into
energetically stable magnetic semiconductors whereas hydrogenation of both the
edges does not affect the electronic and magnetic state of bare ribbons
significantly. The results are promising towards the realization of inorganic
spintronic devices.
