EVIDENCE FOR THE INFLUENCE OF ELECTRON-ELECTRON INTERACTION ON THE CHEMICAL-POTENTIAL OF THE 2-DIMENSIONAL ELECTRON-GAS

It is shown experimentally that the interaction between electrons strongly influences the chemical potential of the two-dimensional (2D) electron gas. At sufficiently low temperatures and in high magnetic fields, regions of filling factor appear where (i) the chemical potential diminishes with increasing carrier density, i.e., the thermodynamic density of states is negative; (ii) the derivative /H (H is the magnetic field) is considerably higher than the maximum value for a noninteracting 2D electron gas. Using these results, we have estimated that the energy of the e-e interaction in Si inversion layers in a magnetic field is about 1 order of magnitude less than the classical Coulomb interaction calculated for Si metal-oxide-semiconductor field-effect transistors. © 1990 The American Physical Society.