Effect of fluctuations on optical properties of diluted magnetic semiconductors with quantum wells in exciton region of spectra

Effects of compositional fluctuations and interface roughness on the exciton scattering in diluted magnetic semiconductor crystals with quantum wells in an external magnetic field were studied. Broadening of the light reflection, transmission and absorption spectra due to the magnetic impurity concentration and spin projection fluctuations was calculated. The fluctuations of both single and pair impurity center distributions, disc from inclusions as well as destruction of antiferromagnetically coupled pairs by a high magnetic field were taken into account. Calculations were performed for quantum wells (Cd,Mn)Te/CdTe/(Cd,Mn)Te. It was shown, that presence of the fluctuations under study allows to explain the bandwidth value in accordance with experiments. Interesting effect of the external magnetic field induced narrowing of the exciton bandwidth was predicted. Step-like magnetic field dependence of the bandwidth due to antiferromagnetically bounded pair destruction was obtained. These peculiarities in the magnetic field dependence of the exciton bandwidth were explained by the coherent summation of spin-dependent and spin-independent parts of the interaction between the exciton and the defects.