Anomalous magnetic properties of electron-irradiated antiferromagnetic copper monoxide

The influence of radiation defects on the magnetic properties of polycrystalline CuO and a high density nanoceramic with crystallite sizes d = 5 and 15 nm has been studied in the temperature range T = 77–300 K. Electron irradiation at fluences Φ = 5 × 10¹⁸ cm^?2 initiated an increase in the susceptibility χ ～ 1/T below 150 K, a feature anomalous for 3D antiferromagnets. The nonlinear behavior of magnetization in weak fields, the increase in the magnetic moment with decreasing temperature, and observation of the spontaneous magnetic moment at temperatures T < 150 K can be attributed to local changes in the exchange parameters and the formation of clusters with uncompensated magnetic moments in the antiferromagnetic matrix near point defects.