Magnetic properties of a spin-polarized two-dimensional electron system

We report on magnetization studies on a two-dimensional electron system (2DES) within a modulation-doped AlGaAs/GaAs-heterostructure where the carrier density can be varied via a gate bias. Oscillations of the sample's magnetization were recorded as a function of the electron density and the magnetic field. Using the Lifshitz-Kosevich theory, a minimum Dingle temperature of about 0.8 K for filling factor v = 2 is deduced from our measurements. We observe the spin-polarized state and for the first time the exchange-enhanced magnetization of the 2DES. The signal strength observed at v = 1 corresponds to an enhanced g*-factor of 14 for B > 6 T. (C) 1998 Elsevier Science B.V. All rights reserved.