Ab initio study of electronic structures and magnetism in ZnMnTe and CdMnTe diluted magnetic semiconductors

In this work, we aimed to examine the spin-polarized electronic band structures, the local densities of states as well as the magnetism of ZnMnTe- and CdMnTe-diluted magnetic semiconductors (DMSs) in the ferromagnetic phase, and with 25% of Mn. The calculations are performed by the recent ab initio full potential augmented plane waves plus local orbitals (FP-L/APW + lo) method within the spin-polarized density-functional theory and the local spin density approximation. We have determined the exchange splittings produced by the Mn d states: Delta(x)(d) and Delta(x)(pd), and we found that the effective potential for the minority spin is more attractive than that for the majority spin. Also, we show the nature of the bonding from the charge spin-densities calculations, and we calculate the exchange constants N-0 alpha and N-0 beta, which mimics a typical magneto-optical experiment. The calculated total magnetic moment is found to be equal to 5(mu B) for both DMSs. This value indicates that every Mn impurity adds no hole carriers to the perfect ZnTe and CdTe crystals. Furthermore, we found that p-d hybridization reduces the local magnetic moment of Mn and produces small local magnetic moments on the nonmagnetic Te, Zn and Cd sites. The several properties predicted in this work for ZnMnTe in the ferromagnetic phase may serve as reference for the other ferromagnetic II-VI DMSs in their alloys and heterostructures. (c) 2005 Elsevier B.V. All rights reserved.