Magnetic circular dichroism spectra in a II-VI diluted magnetic semiconductor Zn1-x Crx Te: First-principles calculations

The absorption and magnetic circular dichroism (MCD) spectra of Zn1-x Crx Te for x=0.0625, 0.25, and 1.0 are studied using the first-principles method. The calculated MCD spectra are found to be well consistent with the experimental measurement at the L critical points (CPs) in spite of opposite MCD sign at absorption edge E0 between calculation and experiment. The MCD signals at these CPs indicate that in Zn1-x Crx Te the p-d exchange interaction does exist and it is ferromagnetic. The MCD spectrum of NiAs-type CrTe is also calculated, which is comparable with the experimental one and totally different from that of Zn1-x Crx Te. All of these results show that the MCD spectra of diluted magnetic semiconductor (DMS) do originate from its band structure and the MCD analysis is efficient in identifying the p-d exchange interaction in it and can be used for discriminating between DMS and other magnetic precipitates in samples.