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

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 O 2 − ions. KO 2 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.