▎ 摘　　要

We theoretically investigate the transport properties of a zigzag graphene nanoribbon, where there exists the Rashba spin-orbit coupling only in the central region modulated by a gate voltage. Using the approach of nonequilibrium Green function, we show that when the two electrode regions are ferromagnetic but the central region is nonmagnetic, the device based on graphene has the behavior of the Datta-Das transistor and at the same time a giant magnetoresistance effect can be observed. Inversely, when the central region has a magnetization but the two electrode regions are nonmagnetic, the device can work as a conductance switch, because an energy gap appears in the band structure of the central graphene ribbon under the coaction of the Rashba spin-orbit coupling and the magnetization. In addition, we find that the behavior of the conductance switch of the device is robust when the weak disorder is present in the system. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790318]