Selective Rashba spin–orbit coupling manipulation in triple quantum wells

Abstract We explore the Rashba ( α ) spin–orbit coupling (SOC) manipulation in AlInSb/InSb triple quantum wells (QWs) with three subbands occupied in the presence of the external gate voltage V b . Diverse behaviors of α can be demonstrated by adjusting the structural parameters of the wells, which is greatly desirable for the design of multifunctional QW-based spintronic devices. Specifically, the first (lowest) subband always has larger Rashba coupling against the variations in the structural parameters and V b than the other subbands, conducive to spin detection. α ν s ( ν = 1, 2, 3 is the subband index) of the second and third subbands take on dual (magnitude and sign) change owing to the regulation of the inner barrier height δ , may facilitating the realization of stretchable persistent spin helix in multiple QWs. Strikingly, α 3 can keep essentially zero in a wide gate range corresponding to asymmetrical QW structural configurations, by adjusting δ . However, when widening the well to a certain extent the δ -dependence of α become fixed, i.e. ∣ α 1 ∣ > ∣ α 2 ∣ > ∣ α 3 ∣ maintains in wide triple-well systems. All these findings may shed light on selective and precise SOC control in QW systems for experiments.