Tuning of Rashba/Dresselhaus Spin Splittings by Inserting Ultra-Thin InAs Layers at Interfaces in Insulating GaAs/AlGaAs Quantum Wells.

Jinling Yu,Qiao Zheng,Shuying Cheng,Jun Ren,Yu Liu,Xiaolin Zeng,Yunfeng Lai,Yonghai Chen

doi:10.1186/s11671-016-1671-7

Abstract

The ratio of Rashba and Dresselhaus spin splittings of the (001)-grown GaAs/AlGaAs quantum wells (QWs), investigated by the spin photocurrent spectra induced by circular photogalvanic effect (CPGE) at inter-band excitation, has been effectively tuned by changing the well width of QWs and by inserting a one-monolayer-thick InAs layer at interfaces of GaAs/AlGaAs QWs. Reflectance difference spectroscopy (RDS) is also employed to study the interface asymmetry of the QWs, whose results are in good agreement with that obtained by CPGE measurements. It is demonstrated that the inserted ultra-thin InAs layers will not only introduce structure inversion asymmetry (SIA), but also result in additional interface inversion asymmetry (IIA), whose effect is much stronger in QWs with smaller well width. It is also found that the inserted InAs layer brings in larger SIA than IIA. The origins of the additional SIA and IIA introduced by the inserted ultra-thin InAs layer have been discussed.

Highlights

Nowadays, spintronics has attracted enormous research interest since it promises to revolutionize electronics and computing by making explicit use of the electron’s spin in addition to its charge [1–3]
spin-orbit coupling (SOC) can be divided into two types, one is Dresselhaus term induced by the bulk inversion asymmetry (BIA)[5] and by interface inversion asymmetry (IIA), and the other is Rashba term induced by the structure inversion asymmetry (SIA)[6–8]
In order to distinguish the circular photogalvanic effect (CPGE) signal related to 1H1E and 1L1E, we should turn to the common photocurrent spectra I1 shown in Fig. 2 to locate the energy positions of 1H1E and 1L1E

Summary

Introduction

Spintronics has attracted enormous research interest since it promises to revolutionize electronics and computing by making explicit use of the electron’s spin in addition to its charge [1–3]. SOC can be divided into two types, one is Dresselhaus term induced by the bulk inversion asymmetry (BIA)[5] and by interface inversion asymmetry (IIA), and the other is Rashba term induced by the structure inversion asymmetry (SIA)[6–8]. As. It has been recognized that Rashba and Dresselhaus SOC can interfere with each other and result in an anisotropy of spin splitting [10]. It has been recognized that Rashba and Dresselhaus SOC can interfere with each other and result in an anisotropy of spin splitting [10] If these two terms have equal strength with each other, the spin splitting in certain k-space directions will vanish. This can lead to some new macroscopic effects, such as the lack of Shubnikovde Haas beating or the disappearance of spin relaxation

Methods

Results

Conclusion