Measurements of the effective g-factor in dilute GaAs 2D electrons

We report direct measurements of g∗ in dilute (density 0.8–View the MathML source), high-mobility GaAs two-dimensional electrons from their spin polarization in a parallel magnetic field. Surprisingly, while g∗ is indeed significantly enhanced with respect to the band g-factor of GaAs, the enhancement factor decreases from about 6 to 3 as the density is reduced.