Distinct Three-Level Spin–Orbit Control Associated with Electrically Controlled Band Swapping* *Supported by the National Natural Science Foundation of China (Grant Nos. 11874236 and 11004120), the QFNU Research Fund, and the Research Program of JNXY.

Abstract

We investigate the Rashba and Dressehaus spin–orbit (SO) couplings in an ordinary GaAs/AlGaAs asymmetric double well, which favors the electron occupancy of three subbands ν = 1, 2, 3. Resorting to an external gate, which adjusts the electron occupancy and the well symmetry, we demonstrate distinct three-level SO control of both Rashba (αν ) and Dresselhaus (βν ) intraband terms. Remarkably, as the gate varies, the first-subband SO parameters α 1 and β 1 comply with the usual linear behavior, while α 2 (β 2) and α 3 (β 3) respectively for the second and third subbands interchange the values, triggered by a gate controlled band swapping. This provides a pathway towards fascinating selective SO control in spintronic applications. Moreover, we observe that the interband Rashba (ημν ) and Dresselhaus (Γμν ) terms also exhibit contrasting gate dependence. Our results should stimulate experiments probing SO couplings in multi-subband wells and adopting relevant SO features in future spintronic devices.