  Electron-electron interactions seem to play a surprisingly small role in the
description of the integer quantum Hall effect, considering that for just
slightly different filling factors the interactions are of utmost importance
causing the interaction-mediated fractional quantum Hall effect. However,
recent imaging experiments by Cobden et al. and Ilani et al. constitute strong
evidence for the importance of electron-electron interactions even in the
integer effect. The experiments report on measurements of the conductance and
electronic compressibility of mesoscopic MOSFET devices that show disagreement
with predictions from the single particle model. By diagonalising a random
distribution of Gaussian scatterers and treating the interactions in
Hartree-Fock approximation we investigate the role of electron-electron
interactions for the integer quantum Hall effect and find good agreement with
the experimental results.
