Magneto-optic effects of n-type modulation-doped GaAs/(Al,Ga)As coupled double quantum wells

yPhotoluminescence measurements of strongly coupled GaAs/AlGaAs double quantum well systems were made in magnetic fields to 18 T. At low fields (below 5 T), the optical transition Landau level selection rule (Deltan = 0) was broken and forbidden transitions (Deltan not equal 0) emerged. Moreover, the lowest Landau level transition (0-0) was missing. With increasing magnetic fields, the (1-0) Landau level transition smoothly approached the (0-0) transition. Such a non-linear optical process is due to the combined effect of formation of a magnetically induced excitonic state and a scattering process induced by interface roughness.