EVIDENCE FOR MAGNETIC EXCITATIONS IN LIQUID-OXYGEN

We briefly describe the results of a neutron scattering study on the dynamics of liquid oxygen (T = 55.0 K, p = 2 bar), performed at a temperature just above the melting point. The wavevector dependence of the inelastic intensities shows a pronounced feature of magnetic origin centred at Q = 1.2 angstrom-1 ('zone boundary') reminiscent of those found in the solid beta-phase. These indicate a dynamical antiferromagnetic (AF) interaction in liquid oxygen at a temperature of approximately 2T(N) (T(N) congruent-to 30 K for solid alpha-phase). The AF coupling extends over only a very short range (congruent-to 5.2 angstrom) and an energy scale of between 0.7 and 3 THz.