Magnetic interactions in a proposed diluted magnetic semiconductor (Ba${}_{\text{1-x}}$K${}_{\text{x}}$)(Zn${}_{\text{1-y}}$Mn${}_{\text{y}}$)${}_{\text{2}}$P${}_{\text{2}}$

Abstract

By using first-principles electronic structure calculations, we have studied the magnetic interactions in a proposed BaZn${}_2$P${}_2$-based diluted magnetic semiconductor (DMS). For a typical compound Ba(Zn${}_{0.944}$Mn${}_{0.056}$)${}_2$P${}_2$ with only spin doping, due to the superexchange interaction between Mn atoms and the lack of itinerant carriers, the short-range antiferromagnetic coupling dominates. Partially substituting K atoms for Ba atoms, which introduces itinerant hole carriers into the $p$ orbitals of P atoms so as to link distant Mn moments with the spin-polarized hole carriers via the $p$-$d$ hybridization between P and Mn atoms, is very crucial for the appearance of ferromagnetism in the compound. Furthermore, applying hydrostatic pressure first enhances and then decreases the ferromagnetic coupling in (Ba${}_{0.75}$K${}_{0.25}$)(Zn${}_{0.944}$Mn${}_{0.056}$)${}_2$P${}_2$ at a turning point around 15 GPa, which results from the combined effects of the pressure-induced variations of electron delocalization and $p$-$d$ hybridization. Compared with the BaZn${}_2$As${}_2$-based DMS, the substitution of P for As can modulate the magnetic coupling effectively. Both the results for BaZn${}_2$P${}_2$-based and BaZn${}_2$As${}_2$-based DMSs demonstrate that the robust antiferromagnetic (AFM) coupling between the nearest Mn-Mn pairs bridged by anions is harmful to improving the performance of this II-II-V based DMS materials.

7 pages, 6 figures, 1 table; Accepted by Chinese Physics B (2018)