Electron Spin Resonance in Cupric Oxide

Abstract

Paramagnetic and antiferromagnetic resonances of powdered CuO are investigated. Very broad paramagnetic resonance with the g -value of about 2.0 is observed above T N at the 45 GHz region under pulsed magnetic field. The linewidth is more than one Tesla and it is explained by the broadening due to the anisotropic exchange interaction between Cu 2+ spins. One-dimensional spin correlation is seen in the line profile. The zero field antiferromagnetic resonance is found by means of the infrared absorption experiments in the temperature range between 5 K and 500 K. Two peaks at 350 and 510 cm -1 with the width of about 100 cm -1 are found. The result suggests that CuO might have a multisublattice structure even at low temperatures.