Mott physics in the 2p electron dioxygenyl magnet O₂MF ₆ (M=Sb, Pt)

We have investigated electronic structures and magnetic properties of O₂MF₆ (M=Sb, Pt), which are composed of two building blocks of strongly correlated electrons: O₂⁺ dioxygenyls and MF₆^- octahedra, by employing the first-principles electronic structure band method. For O₂SbF₆, as a reference system of O₂PtF₆, we have shown that the Coulomb correlation of O(2p) electrons drives the Mott insulating state. For O ₂PtF₆, we have demonstrated that the Mott insulating state is induced by the combined effects of the Coulomb correlation of O(2p) and Pt(5d) electrons and the spin-orbit (SO) interaction of Pt(5d) states. The role of the SO interaction in forming the Mott insulating state of O ₂PtF₆ is similar to the case of Sr₂IrO ₄ that is a prototype of a SO-induced Mott system with J _eff=1/2.