  A method to produce a spin-dependent rotating potential using near-resonant
circularly polarized laser beams is proposed. It is shown that half-quantum
vortices are nucleated in a spinor Bose-Einstein condensate with an
antiferromagnetic interaction. In contrast to the vortex nucleation in a scalar
BEC, the spin-vortex nucleation occurs at a low rotation frequency ($\simeq 0.1
\omega_\perp$ with $\omega_\perp$ being the radial trap frequency) in a short
nucleation time $\simeq 50$ ms without dissipation. A method for nondestructive
measurement of half-quantum vortices is discussed.
