Exciton oscillator strength in magnetic-field-induced spin superlattices CdTe/(Cd,Mn)Te

Resonance-reflectivity data on CdTe/(Cd,Mn)Te quantum wells and superlattices are analyzed to obtain the exciton longitudinal-transverse splitting or oscillator strength as a function of the layer widths and/or the band offsets altered by externally applied magnetic fields. A nonlocal-dielectric-response theory for single quantum wells and the concept of an optically homogeneous dielectric medium formulated for periodic structures are developed. Strong effects of the magnetic-field-induced type-I–type-II transition and the spin-superlattice formation for holes on the exciton oscillator strength are found to be in agreement with our calculations.