Tunable interfacial Rashba spin–orbit coupling in asymmetric AlxIn1−xSb/InSb/CdTe quantum well heterostructures

Abstract

We report the manipulation of the Rashba-type spin–orbit coupling (SOC) in molecular beam epitaxy-grown AlxIn1−xSb/InSb/CdTe quantum well heterostructures. The effective band bending warrants a robust two-dimensional quantum confinement effect, and the unidirectional built-in electric field arisen from the asymmetric hetero-interfaces leads to a pronounced Rashba SOC strength. By tuning the Al concentration in the top AlxIn1−xSb barrier layer, the optimal structure of x = 0.15 exhibits the largest Rashba coefficient of 0.23 eV Å as well as the highest low-temperature electron mobility of 4400 cm2 · V−1 · s−1. Moreover, quantitative investigations of the weak anti-localization effect further justify the prevailing D'yakonov–Perel spin relaxation mechanism during the charge-to-spin conversion process. Our results underscore the importance of quantum well engineering in shaping the magneto-resistance responses, and the narrow bandgap semiconductor-based heterostructures may serve as a reliable framework for designing energy-efficient spintronic applications.