Magnetisation of condensed oxygen under high pressures and in strong magnetic fields

The variation of the magnetic susceptibility of condensed oxygen with temperature and hydrostatic pressure up to 0.6 GPa has been investigated. The results yield an empirical relation between the exchange parameter and the intermolecular distance. High-field magnetisation data on alpha -oxygen indicate a spin-flop; the corresponding anisotropy agrees fairly well with results of magnetic dipole calculations which also include a prediction for the direction of the magnetisation axis. Evidence is presented for magnetic long-range order in beta -oxygen.