| Abstrakt: |
The inner barrier in stepped quantum wells, which embrace an intrinsic structural inversion asymmetry (SIA), offers more possibilities for the multi-band spin–orbit (SO) control. By varying the inner band offset δ , which adjusts the quantum confinement for electrons and also the SIA, we reveal that both the Rashba ( α ν ) and Dresselhaus ( β ν ) SO coeffcients of the two subbands exhibit contrasting dependence on δ. Also, α 1 and α 2 may have opposite signs, depending on the value of δ. By fine tuning the inner offset, there may even exist a scenario in which α 2 identically vanishes but α 1 is finite, offering a knob on how to subband-selectively suppress spin relaxation induced by SO coupling. In addition, by resorting to an external gate V g , we reveal that in the regime of α 1 and α 2 having opposite signs, their magnitudes also vary with V g in an opposite manner. This, together with the engineered inner barrier of stepped wells, will facilitate flexible spin manipulation. Finally, the interband SO couplings, which depend on the spatial overlap of wave functions of distinct subbands and the corresponding parities, are also discussed. [ABSTRACT FROM AUTHOR] |
