Y-shaped spin filter in graphene with rashba spin-orbit coupling

We propose a graphene Y-shaped spin filter with three zigzag-edged terminals in the presence of the Rashba spin- orbit interaction (RSOI). The three terminal spin-dependent conductances are calculated numerically using the lattice Green function. The results show that the spin polarization is nearly 100% for strong spin-orbit coupling and a suitable Fermi energy. The polarization direction can be tuned by controlling the structure parameters. It is interesting that the conductance of the first channel is heavily suppressed by the edge states localized at the edges of the zigzag ribbon terminals and can be significantly enhanced by Rashba coupling at the junction. © 2013 The Physical Society of Japan.