Magnetic symmetry of <i>β</i>-oxygen
Abstract
The existence of a long-range magnetic order of the nonorientational (correlation) type in the rhombohedral modification of crystalline oxygen is predicted on the basis of symmetry analysis. In this phase, the time-averaged spin of each O2 molecule in the crystal is equal to zero. Nevertheless, the magnetic symmetry of the system is found to be half the symmetry of the true paramagnetic state. The existence of the long-range correlation spin ordering is determined by exchange intermolecular spin–spin interactions which are rather strong in crystalline oxygen (∼102 K). The absence of conventional orientational long-range order is associated in this case with the two-dimensional nature of spin–spin interactions and with a special symmetry of the system.