Spatial anisotropy of the exchange integrals in Mn-doped wurtzite-type semiconductors

 
A. M. Daré,
 
A. Savoyant,
 
S. D"Ambrosio,
 
A. Stepanov
 

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Phys. Rev. B - Maryland, USA: American Physical Society (APS), 2011, #84
http://www.materials.kiev.ua/article/642

Abstract

We propose an alternative explanation, as compared to one reported in the literature, to the experimentally observed spatial anisotropy ξ=ΔJ1/J1in (ΔJ1=J1in-J1out) of the nearest neighbor exchange integral J1 in Mn-doped semiconductors with the wurtzite structure. We show that the main contribution to ξ is ferromagnetic and comes from a looped exchange path which involves two distinct anions. A comparison between our calculations, that use the results of photoemission spectroscopy as input parameters, and the available data for three wurtzite materials, CdS:Mn, CdSe:Mn, and ZnO:Mn, shows a good quantitative agreement between theory and experiment in the case of cadmium compounds and only a qualitative one in the case of ZnO:Mn.