Faraday rotation in a study of charged excitons in Cd1-xMnxTe

Interband Faraday rotation is usually interpreted as resulting from a difference in refractive indices caused by the Zeeman effect in a magnetic field. We show that, in the case of transitions due to the creation of excitons in semiconductor quantum wells containing charge carriers, a strong dependence of the line amplitude on the circular polarization in the presence of a magnetic field can also generate Faraday rotation. The spectral dependence of this Faraday rotation is completely different from that in the usual case. We demonstrate that the amplitude-related Faraday effect can dominate the rotation spectrum of charged excitons. We show that the Faraday rotation is particularly useful in studies of excitons in quantum wells with two-dimensional carrier gas where line intensities vary strongly with magnetic field.