Exchange-enhanced energy shifts in the polarized photoluminescence of a two-dimensional hole system in the integer quantum Hall regime

Polarized photoluminescence spectroscopy studies have been performed on two-dimensional hole systems in GaAs-(Al,Ga)As one-side modulation-doped quantum wells in the integer quantum Hall effect regime. Energy shifts of the photoluminescence are observed at integer filling factors. For $\nu >~2,$ the energies of the photoluminescence in the right- and left-circular polarizations are almost equal near even filling factors and maximally separated near odd filling factors. This behavior is attributed to a combination of many-body effects in the screening of the correlation hole of the photoexcited electrons and an exchange-enhanced Zeeman splitting at odd filling factors. At $\nu =1\mathrm{}$ upward energy shifts are seen in both polarizations; in contrast to the behavior at other odd filling factors, the transition energies in the two polarizations are almost equal instead of being maximally separated. This is attributed to the occurrence of filling factor $\nu =1\mathrm{}$ in a region of magnetic field where there is strong mixing of the heavy-hole and light-hole states.