Wave-like transmission in waveguides with spatially modulated strengths of the Rashba and Dresselhaus terms of the spin–orbit interaction

We evaluate the electron transmission T through waveguides (WGs) in which the strengths of the Rashba (α) and Dresselhaus (β) terms of the spin–orbit interaction (SOI) vary in space. For sufficiently narrow WGs T exhibits a spin–transistor behavior as a function of α or β and of α/β or β/α. In addition, T shows resonances, as a function of the length of a SOI-free region separating two regions with SOI present, which become sharper when the length of the latter is increased and are most pronounced for α=β. The sign of α strongly affects the spin-up and spin-down transmissions. The results are pertinent to the development of a spin transistor.