  We have studied zig-zag boron nitride (BN) nanotubes doped with the Ni
hexagonal-closepacked nanowire. The doped BN nanotubes are ferromagnetic metals
with substantial magnetism. Some special magnetic properties resulting from the
interaction between the Ni nanowire and BN nanotubes are found. The Ni doped
BN(9,0) nanotube shows semi-half-metallic behavior, which could become
half-metallic after doping electrons more than 1.4 e/unit cell. The intrinsic
halfmetallic behavior could be achieved by two dierent ways: one is coating the
Ni nanowire with a smaller BN nanotube, i.e., BN(8,0), the other is using
hydrostatic pressure to homogeneously compress the Ni doped BN(9,0) nanotube.
