Suppression of spin-splitting in Al_(0.33)Ga_(0.67)As/Al_yGa_(1-y) As heterostructures with y varying from 0.10 to 0.15

摘要

The Al_(0.33)Ga_(0.67)As/Al_yGa_(1-y) As heterostructure can be used to create a two-dimensional electron gas with Lande g-factor g ≈ 0 for y in the region 0.10 to 0.15. A spin-splitting can be observed in the longitudinal magnetoresistance (p_(xx)) with a high magnetic field (23 T) applied at angles close to the plane of the two-dimensional electron gas. The precise behaviour of p_(xx) with increasing in-plane field depends on the composition of the conducting layer. The appearance of spin-splitting in p_(xx) does not necessarily invalidate the g ≈ 0 condition. We discuss this result in the context of the competing role played by disorder, g-factor enhancement due to exchange interaction and the recently observed Stoner transition in a two-dimensional electron gas. The effect of wavefunction extent at the heterointerface is also considered. The Al_yGa_(1-y)As material system may have applications in the disentanglement of spin states in quantum information processing when incorporated into double well systems for use in more accessible magnetic field ranges.