Magnetoelastic Interactions in Ionic π -Electron Systems: Magnetogyration

The alkali hyperoxides AO₂ exhibit elastic and magnetic interactions due to the nature of the diatomic molecule ion O₂^-. These anion sublattices represent simple magnetic spin-{} systems. In contrast to $3d$- or $4f$-electron systems, where magnetoelastic interactions induce magnetostriction, the (2p)π-electron system KO₂ exhibits magnetogyration. A crystallographic phase transition involving a considerable change in the molecular orientation can be induced by an applied magnetic field. A theoretical model based on the exchange modulation produced by this reorientation describes the salient features.