Improved half-metallic ferromagnetism of transition-metal pnictides and chalcogenides calculated with a modified Becke-Johnson exchange potential

San-Dong Guo and Bang-Gui Liu(a)

Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China


Abstract. 

We use a density-functional-theory (DFT) approach with a modified Becke-Johnson exchange plus local density approximation (LDA) correlation potential (mBJLDA) [semi-local, orbital-independent, producing accurate semiconductor gaps. see F. Tran and P. Blaha, Phys. Rev. Lett. 102, 226401 (2009)] to investigate the electronic structures of zincblende transitionmetal (TM) pnictides and chalcogenides akin to semiconductors. Our results show that this potential does not yield visible changes in wide TM d-t2g bands near the Fermi level, but makes the occupied minority-spin p-bands lower by 0.25∼0.35 eV and the empty (or nearly empty) minority-spin eg bands across the Fermi level higher by 0.33∼0.73 eV. Consequently, mBJLDA, having no atom-dependent parameters, makes zincblende MnAs become a truly half-metallic (HM) ferromagnet with a HM gap (the key parameter) 0.318eV, being consistent with experiment. For zincblende MnSb, CrAs, CrSb, CrSe, or CrTe, the HM gap is enhanced by 19∼56% compared to LDA and generalized gradient approximation results. The improved HM ferromagnetism can be understood in terms of the mBJLDA-enhanced spin exchange splitting. 


To download the article click on the link below:

https://arxiv.org/pdf/1009.1920.pdf