Nature of charge transport and p-electron ferromagnetism in nitrogen-doped ZrO2: an ab initio perspective.

Zirconium dioxide provides an exceptional prototype material for studying the redistribution of the polaron holes and its magnetic coupling with their nearby anions owning to the difference oxygen binding behavior in the monoclinic phase. Here, we perform a comprehensive study of the p-electron magnetism in the nitrogen doped 2 × 2 × 2 monoclinic ZrO2 based on spin-polarized density functional theory. Nitrogen substitutions make the system display half-metallic properties, and the origin of room temperature ferromagnetism ascribes to the p-p coupling interaction between N 2p and the host 2p states. The charge density difference and Mülliken population analyses provide evidences of charge redistributions. Our results reveal that the polaron transfer may alter the magnetic properties and it is greatly facilitated ferromagnetic coupling if the polaron holes are localized around a single anion dopant.