Off-diagonal s-d coupling and red shift of absorption spectra in magnetic semiconductors

Using the method of moments, it is argued that the strong coupling s-d model gives an appreciably enhanced red shift of the quasiparticle density of states with temperature due to even a weak off-diagonal s-d coupling contribution as compared to the case with only a diagonal coupling. The result is used to interpret the red shift in chromium chalcogenide spinels.