Chemical trend of exchange couplings in diluted magnetic II-VI semiconductors - Condensed Matter > Strongly Correlated Electrons

Abstract: We have calculated the chemical trend of magnetic exchange parameters$J {dd}$, $N \alpha$, and $N \beta$ of Zn-based II-VI semiconductors ZnAA=O, S, Se, and Te doped with Co or Mn. We show that a proper treatment ofelectron correlations by the LSDA+$U$ method leads to good agreement betweenexperimental and theoretical values of the nearest-neighbor exchange coupling$J {dd}$ between localized 3$d$ spins in contrast to the LSDA method. Theexchange couplings between localized spins and doped electrons in theconduction band $N \alpha$ are in good agreement with experiment as well. Butthe values for $N \beta$ coupling to doped holes in the valence band indicatea cross-over from weak coupling for A=Te and Se to strong coupling for A=Oand a localized hole state in ZnO:Mn. That hole localization explains theapparent discrepancy between photoemission and magneto-optical data for ZnO:Mn.

Author: T. Chanier, F. Virot, R. Hayn

Source: https://arxiv.org/