Coexistence of localized and itinerant magnetism in newly discovered iron-selenide superconductor LiFeO2Fe2Se2

The electronic structure and magnetism of LiFeO${}_2$Fe${}_2$Se${}_2$ are investigated using the first-principle calculations. The ground state is N$\acute{e}$el antiferromagnetic (AFM) Mott insulating state for Fe1 with localized magnetism in LiFeO${}_2$ layer and striped AFM metallic state for Fe2 with itinerant magnetism in Fe${}_2$Se${}_2$ layer, accompanied with a weak interlayer AFM coupling between Fe1 and Fe2 ions, resulting in a coexistence of localized and itinerant magnetism. Moreover, the layered LiFeO${}_2$ is found to be more than an insulating block layer but responsible for enhanced AFM correlation in Fe${}_2$Se${}_2$ layer through the interlayer magnetic coupling. The interplay between the magnetisms of Fe1 and Fe2 introduces a control mechanism for spin fluctuations associated with superconductivity in iron-based superconductors.