Spin splitting and switching effect in a four-terminal two-dimensional electron gas nanostructure.

We have studied the spin-splitting effect in a four-terminal two-dimensional (2D) electron gas system with two potential barriers generated by two surface metal gates and an external perpendicular magnetic field. The calculations show that by tuning the voltage applied on the gates, the injected spin-unpolarized current can be split into different spin currents with a high efficiency. The split currents flow out of the geometry from different output leads separately. The spin freedom of the outputs can be controlled by simply tuning voltage on gates. This phenomenon is a result of the combination of three effects - the potential barriers, Zeeman splitting and edge current. Furthermore, by tuning the voltage on gates, the outflow spin of current in one terminal can be switched. Therefore, these features open up a possibility for making a spin filter or a switcher device by applying the four-terminal 2D electron gas system.