Mobility dependence on carrier density in a dilute GaAs electron gas in an in-plane magnetic field

We report low-temperature magnetoresistivity measurements of a high-quality gated two-dimensional electron gas (2DEG). In the dilute electron density limit, we show evidence for spin polarisation in an in-plane magnetic field. Using a simple model, we estimate the Landé g-factor in this dilute 2DEG to be about 3.32. This enhanced Landé g-factor compared with that of a bulk GaAs 2D electron system (0.44) is ascribed to electron–electron interaction effects at ultra-low electron densities and the fact that over the whole measurement range rs does not vary significantly. Moreover, we report the mobility μ dependence on electron density n of a dilute electron gas at different in-plane magnetic fields. It is found that the exponent α in the relation μ∝nα increases with increasing in-plane magnetic field. We ascribe this effect to the combination of increasing scattering and spin polarisation with increasing parallel magnetic field.