Spin-splitting renormalization in the neutral dense magnetoplasma in ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/InP quantum wells

Photoluminescence spectra of the neutral dense (${\mathit{n}}_{\mathrm{eh}}$<2×${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$) magnetoplasma photoexcited in ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/InP single quantum wells have been investigated in ${\mathrm{\sigma }}^{+}$ and ${\mathrm{\sigma }}^{\mathrm{-}}$ polarizations. Fine structure of Landau-level transitions has been observed which is caused by the mixture of hole-spin states. A considerable enhancement of electron and hole spin splittings of the zero and first Landau levels arises when the uppermost occupied Landau levels with different spins are unequally filled. An explanation is offered in terms of the exchange inter-Landau-level interactions.