Photoluminescence in integer quantum Hall systems

Photoluminescence spectra in two-dimensional systems in the quantum Hall regime nugreater than or equal to2 are studied using a numerical diagonalization method, where nu is the filling factor. The first moment of the spectra is understood in terms of the nu-dependent screening effect. The spectra of left-circularly polarized light usually exhibit a double-peak structure when 2<= 4, in qualitative agreement with recent experiments. Those of right-circularly polarized light show only a single peak when 2 <=nu <= 3 and a double-peak structure when 3 <=nu <= 4. The origin of this double-peak structure is strong hybridization between optically allowed and forbidden final states through inter-Landau-level scattering between electrons with opposite spins.