  A proposal of electrically controlled spin transistor in helical magnetic
field is presented. In the proposed device, the transistor action is driven by
the Landau-Zener transitions that lead to a backscattering of spin polarized
electrons and switching the transistor into the high-resistance state (off
state). The on/off state of the transistor can be controlled by the
all-electric means using Rashba spin-orbit coupling that can be tuned by the
voltages applied to the side electrodes.
