Etude de l’effet Jahn-Teller sur les impuretés 3d dans les semiconducteurs III-V et II-VI avec la méthode FP-LAPW

Abstract

We present an ab-initio and analytical study of the Jahn-Teller effect in two diluted magnetic Semiconductors (DMS) with d4 impurities, namely Mn-doped GaN (III-V) and Cr-doped ZnS( II-VI). We show that only the combined treatment of Jahn-Teller distortion and strong electron correlation in the 3d shell may lead to the correct insulating electronic structure. Using the LSDA+U approach we obtain the Jahn-Teller energy gain in reasonable agreement with the available experimental data. The ab-initio results are completed by a more phenomenological ligand field theory.