The magnetic structure and magnetization distribution of the intermetallic compound U₁₄Au₅₁
The antiferromagnetic structure of the intermetallic compound U₁₄Au₅₁ has been determined from neutron polarimetric measurements and refined by combining these data with integrated intensity measurements. The structure was found to be non-collinear with the U moments confined to the a- b plane. The moments of the U atoms in each of the two sets of sixfold sites are arranged hexagonally with rotations of 60° between them and the two sets are rotated with respect to each other by 50°. The third (twofold) set of U atoms has no ordered moment. These conclusions are in disagreement with a previous determination of the magnetic structure from powder data which gave a collinear structure with moments parallel to the c-axis. Magnetization measurements made on single crystals in the temperature range 300-2K can be understood in terms of a transition to a non-collinear easy plane antiferromagnetic structure stable below 22K. Polarized neutron measurements have been used to determine the contribution of each of the U sites to the susceptibility between 22 and 2K. These show that of the two sixfold U sites, that with the smaller ordered moment contributes more than half of the total susceptibility. The twofold site, which is characterized by a small U-U separation, makes the smallest contribution.