First-principles study on the electronic structures and magnetic properties of a diluted magnetic semiconductor Ba1−xKx(Zn1−yMny)2As2

Abstract

Within Perdew-Burke-Ernzerhof generalized gradient approximation, first-principles calculations were performed to investigate the electronic structures and magnetic properties of II–II–V based DMS (Ba,K)(Zn,Mn)2As2 with holes doped via (Ba2+, K1+) replacements, and spins via isovalent (Zn2+, Mn2+) substitutions. Compound BaZn2As2 is paramagnetic semiconductor with a calculated band gap 0.28 eV. With Mn–Mn pair doped in different distances, Ba(Zn1−yMny)2As2 (y = 0.03125) system shows antiferromagnetic behaviour caused by the short-range superexchange interactions between localized spins of Mn2+ ions. Holes introduced by K dopants lead to metallic behaviour in (Ba1−xKx)(Zn1−yMny)2As2 system and drive the system toward ferromagnetism. The ferromagnetic coupling in the Mn–Mn pair is attributed to the long-range p−d exchange interactions mediated by itinerant holes. Competition between the antiferromagnetic superexchange and ferromagnetic interaction in the Mn–Mn pair determines the magnetic order of (Ba1−xKx)(Zn1−yMny)2As2 system, and the competition is dependent on both the concentration and distribution of K dopants.