Spin-orbital superexchange physics emerging from interacting oxygen molecules in KO2

Abstract

We propose that the spin-orbital-lattice coupled phenomena, widely known for the transition-metal oxides, can be realized in molecular solids, comprising of orbitally degenerate magnetic O2- ions. KO2 is one such system. Using the first-principles electronic structure calculations, we set-up an effective spin-orbital superexchange model for the low-energy molecular bands and argue that many anomalous properties of KO 2 indeed replicate the status of its orbital system in different temperature regimes. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.