Electron transport in waveguides with spatially modulated strengths of the Rashba and Dresselhaus terms of the spin-orbit interaction

摘要

We study electron transport through waveguides (WGs) in which the strengthsof the Rashba ($\alpha$) and Dresselhaus ($\beta$) terms of the spin-orbitinteraction (SOI) vary in space. Subband mixing, due to lateral confinement, istaken into account only between the two first subbands. For sufficiently narrowWGs the transmission $T$ exhibits a square-like shape as a function of $\alpha$or $\beta$. Particular attention is paid to the case of equal SOI strengths,$\alpha=\beta$, for which spin-flip processes are expected to decrease. Thetransmission exhibits resonances as a function of the length of a SOI-freeregion separating two regions with SOI present, that are most pronounced for$\alpha=\beta$. The sign of $\alpha$ strongly affects the spin-up and spin-downtransmissions. The results show that the main effect of subband mixing is toshift the transmission resonances and to decrease the transmission from onespin state to another. The effect of possible band offsets between regions thathave different SOI strengths and effective masses is also discussed.