Far-infrared spectroscopy of solid α-oxygen in magnetic fields up to 15 tesla

Abstract

The antiferromagnetic resonance modes of alpha -oxygen have been measured below and above the spin-flop field. Spin wave theory is developed and is found to describe the experimental data if one disregards a constant frequency shift. The temperature dependence of the mode frequencies is discussed. The ratio of the intensities of the two magnons at low temperatures and zero field is derived, both theoretically and from experimental data.