MAGNETIZATION AND NEUTRON-SCATTERING STUDIES OF MULTIAXIAL MAGNETIC-ORDERING IN USB0.9TE0.1

USb is a simple type I antiferromagnet, but USb0.9Te 0.1 shows most unusual behaviour. Studies have been undertaken on single crystals in an attempt to understand this behaviour. Below T N=203+or-2K an ordering takes place with a wavevector k=(00k) that is nearly commensurate; k=2/3- delta with delta =0.040 at TN. At 160K a first-order phase transitions occurs to a commensurate phase k=2/3. Magnetisation measurements in this phase given a saturated moment of 0.92 mu B/U atom, which is a factor of three less than that found for USb (2.85+or-0.05 mu B). The easy axis is <111>; the moments in the other principle directions are given by the cosine law. The only magnetic structure compatible with the present measurements is one described by three square-wave components propagating along the cube edges simultaneously.