Suppression of spin-splitting in Al0.33Ga0.67As/AlyGa1-yAs heterostructures with y varying from 0.10 to 0.15

The Al0.33Ga0.67As/ Al-y Ga1-y As heterostructure can be used to create a two-dimensional electron gas with Lande g-factor g approximate to 0 for y in the region 0.10 to 0.15. A spin-splitting can be observed in the longitudinal magnetoresistance (rho(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 rho(xx) with increasing in-plane field depends on the composition of the conducting layer. The appearance of spin-splitting in rho(xx) does not necessarily invalidate the g approximate to 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 AlyGa1-yAs 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.