Magnetic circular dichroism spectra in a II-VI diluted magnetic semiconductorZn1−xCrxTe: First-principles calculations

Abstract

The absorption and magnetic circular dichroism (MCD) spectra of ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}\mathrm{Te}$ 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 ${E}_{0}$ between calculation and experiment. The MCD signals at these CPs indicate that in ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}\mathrm{Te}$ the $p\text{\ensuremath{-}}d$ 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 ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}\mathrm{Te}$. 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 $p\text{\ensuremath{-}}d$ exchange interaction in it and can be used for discriminating between DMS and other magnetic precipitates in samples.