LIGHT-SCATTERING FROM A PERIODICALLY MODULATED 2-DIMENSIONAL ELECTRON-GAS WITH PARTIALLY FILLED LANDAU-LEVELS

We study light scattering from a periodically modulated two-dimensiona l electron gas in a perpendicular magnetic field. If a subband is part ially filled, the imaginary part of the dielectric function as a funct ion of frequency contains additional discontinuities to the case of co mpletely filled subbands. The positions of the discontinuities may be determined from the partial filling factor and the height of the disco ntinuity can be directly related to the modulation potential. The ligh t-scattering cross section contains a peak which is absent for integer filling.