Spin susceptibility and effective mass of a 2D electron system in GaAs heterostructures towards the weak interacting regime

We determined the spin susceptibility χ and the effective mass m* towards the high density limit. Using a tunable GaAs/AlGaAs heterostructure, we can vary the 2D electron density from n=1×1010cm-2 to 4×1011cm-2. From ∼5×1010cm-2 to our highest densities the mass values fall ∼10% below the band mass of GaAs. The enhancement of χ decreases monotonically from a factor of 3 to 0.88 with increasing density. It continues to follow a previously observed power law, which leads to an unphysical limit for n→∞. Band structure effects affecting mass and g-factor become appreciable for large n and, when taken into account, lead to the correct limiting behavior of χ. Numerical calculations are in qualitative agreement with our data but differ in detail.