  A mechanism to generate a spin-polarized current in a two-terminal zigzag
silicene nanoribbon is predicted. As a weak local exchange field that is
parallel to the surface of silicene is applied on one of edges of the silicene
nanoribbon, a gap is opened in the corresponding gapless edge states but
another pair of gapless edge states with opposite spin are still protected by
the time-reversal symmetry. Hence, a spin-polarized current can be induced in
the gap opened by the local exchange field in this two-terminal system. What is
important is that the spin-polarized current can be obtained even in the
absence of Rashba spin-orbit coupling and in the case of the very weak exchange
filed. That is to say, the mechanism to generate the spin-polarized currents
can be easily realized experimentally.We also find that the spin-polarized
current is insensitive to weak disorder.
