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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.



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


Fuente: https://arxiv.org/



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