Magnetic interactions in a proposed diluted magnetic semiconductor (Ba1−xKx)(Zn1−yMny)2P2**Project supported by the National Key Research and Development Program of China (Grant No. 2017YFA0302903), the National Natural Science Foundation of China (Grant Nos. 11774422 and 11774424), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant Nos. 14XNLQ03 and 16XNLQ01).

Abstract

By using first-principles electronic structure calculations, we have studied the magnetic interactions in a proposed BaZn2P2-based diluted magnetic semiconductor (DMS). For a typical compound Ba(Zn0.944Mn0.056)2P2 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 (Ba0.75K0.25)(Zn0.944Mn0.056)2P2 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 BaZn2As2-based DMS, the substitution of P for As can modulate the magnetic coupling effectively. Both the results for BaZn2P2-based and BaZn2As2-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 these II–II–V based DMS materials.