Magnetic properties of uranium chalcogenides with composition close to UY2

The magnetic and some related physical properties of the uranium dichalcogenides are summarized and discussed with regard to their crystal structure. The theoretical magnetic susceptibility calculated on the basis of the usual crystal-field theory is compared with the experimental data. The calculation was carried out under the assumption that the uranium ions have the pure ³H₄ term and that there are S^2?, Se^2? and Te^2? ions. Regardless of the crystal environment of the uranium ion in all types of compounds the ground state appears to be a singlet. The results agree with experiment in a considerably broad temperature range. α-Dichalcogenides and U₇Te₁₂ exhibit a magnetic transition at low temperatures. Their unusual behavior in this region is discussed in terms of their crystal-field levels, complicated magnetic structure and possible magnetocrystalline anisotropy.