Spin-polarized quantum pumping in bilayer graphene.

We study adiabatic quantum pumping in bilayer graphene where two-barrier potentials are weakly modulated as pumping parameters. Comparing the results with those for a normal quantum pump of non-chiral quasiparticles, we find that the chirality of quasiparticles in bilayer graphene heavily affects the pumped current through chiral tunnelling. When an exchange splitting induced by the proximity of a ferromagnetic insulator is introduced, the pumped current becomes spin-polarized. It is interesting that an almost 100% polarized charge current and a pure spin current with vanishing charge current can all be achieved under suitable conditions. The experimental feasibility and the interlayer asymmetric effect in bilayer graphene caused by the gate and the ferromagnet structures are also discussed. The results are useful for spintronics applications based on graphene.