  The effect of chemical doping on the ZSiNRs with Mn as passivating element
replacing H atoms at one edge are investigated by first principles
calculations.The structures optimized in the typical ferromagnetic and
antiferromagnetic coupling show that the system leads to an AFM state and
achieve half metallic properties.Also,our first principle approach based on the
Keldysh nonequilibrium Greens function method gives the spin dependent
transport properties of the device. When the system changes from parallel to
antiparallel configuration. the spin up current increases rapidly while the
spin down current is still depressed. Further, it is found that the system is a
quite good spin filtering device with nearly 80 percent spin filtering
efficiency at a wide bias voltage region and therefore suitable for
applications. The mechanisms for these phenomena are proposed in detail.
