Spin-dependent transport in a dilute two-dimensional GaAs electron gas in a parallel 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 polarization 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 two-dimensional (2D) electron system (0.44) is ascribed to electron-electron interaction effects at ultralow electron densities and the fact that over the whole measurement range $r_s$ does not vary significantly.