Weak Ferromagnetism in Antiferromagnetic UO2

Abstract

A nearly isotropic weak ferromagnetism has been observed by the torque method in single crystals of U${\mathrm{O}}_2$ below the Néel temperature. Measurements were made of remanence produced by cooling samples from $T>\mathrm{}{T}_N$ down to 4.2°K in fields up to 32 kOe or by cooling in zero field to 4.2°K followed by the isothermal application of the field. The largest remanence observed was 5.7×${10}^{-2\mathrm{}}$ emu/g. Upon warming from 4.2°K toward $T_N$, the remanence diminishes with increasing rapidity and then levels off abruptly at $T_N$ at a small residual value. The curve of remanence versus temperature is markedly different for the two types of magnetic treatment.