Magneto-optics of the spatially separated electron and hole layers in ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ coupled quantum wells

We report on the magneto-optical study of the spatially separated electron and hole layers in ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ coupled quantum wells at low temperatures $T>~50\mathrm{mK}$ and high magnetic fields $B<~16\mathrm{T}.$ At high magnetic fields cusps are observed in the energy and intensity of the indirect (interwell) exciton photoluminescence. We tentatively attribute these to the commensurability effects of the magnetoexciton with island structures in the sample. The indirect exciton lifetime is found to increase with magnetic field. The increase is attributed to the reduction of indirect exciton localization area caused by the increase of the magnetoexciton mass. The indirect exciton photoluminescence energy is found to enhance with density, which reflects the net repulsive interaction between indirect excitons.