2p -insulator heterointerfaces : Creation of half-metallicity and anionogenic ferromagnetism via double exchange

We use first-principles calculations to predict the occurrence of half-metallicity and anionogenic ferromagnetism at the heterointerface between two 2p insulators, taking the KO2/BaO2 (001) interface as an example. Whereas a sharp heterointerface is semiconducting, a heterointerface with a moderate concentration of swapped K and Ba atoms is half-metallic and ferromagnetic at ambient pressure due to the double exchange mechanism. The K-Ba swap renders the interfacial K-O and Ba-O atomic layers electron-doped and hole-doped, respectively. Our findings pave the way to realize metallicity and ferromagnetism at the interface between two 2p insulators, and such systems can constitute a new family of heterostructures with novel properties, expanding studies on heterointerfaces from 3d insulators to 2p insulators.