SPIN SPLITTING IN A TWO DIMENSIONAL ELECTRON SYSTEM DETERMINED BY NUCLEAR MAGNETIC RELAXATION AND MAGNETOTRANSPORT ACTIVATION MEASUREMENTS

The spin splitting observed in two-dimensional electron systems at high magnetic fields is not only determined by the single-electron Zeeman energy but also by many-particle effects. Electron-electron interaction results in an enhanced g-factor which can be described by the exchange part of the Coulomb interaction. Nuclear spin lattice relaxation experiments analysing the Overhauser Shift in Electron Spin Resonance (ESR) measurements reveal that the exchange term is dominant. The spin splitting is strongly dependent on magnetic field and temperature. Numerical simulations enable the quantitative determination of the exchange part of the spin split energy. Transport activation measurements verify that the exchange part is proportional to the spin polarization of the electrons.