  Low-temperature screening properties of the inhomogeneous two-dimensional
electron gas in a Hall bar subjected to a strong perpendicular magnetic field
are explored using a self-consitent approach. An external oscillating
modulation potential with an amplitude of the order of the cyclotron energy is
added to the electron-confining background potential, and the resulting change
of the self-consistent potential is investigated as a function of modulation
strength, magnetic field, and temperature. The consequences of Landau-level
pinning and the interplay of compressible and incompressible regions for the
resulting strongly non-linear screening phenomena are explained.
