Correlation effects in Cr-Zinc chalogenides

The electronic properties and self-interaction effects of Zn1−xCrxTe (with x = 0.03125 and 0.0625), using the local spin density Approximation with a Hubbard term to improve the description of the d-Cr orbitals, is presented. These materials have potential technological applications as half-metallic and intermediate band materials. For a sufficiently high density of Cr substituting the Zn atoms they have an intermediate band in the host semiconductor band gap for a one spin component, with the Fermi energy located within the impurity band. An increase in the Cr concentration causes an overlap of the intermediate band with the valence band, leading to only half-metallic behaviour. One would expect a substantial shift in the position of the Cr d-bands due to the local Coulomb interaction. However, the Coulomb interaction induces almost no changes in the occupied bands. The expected shift is indeed observed in the conduction band. This point is analyzed and a comparison with other zinc chalogenides is made in accordance with the interactions Cr-host semiconductor.