MAGNETIC AND STRUCTURAL PHASE-TRANSITIONS IN UAU2SI2

We report magnetic susceptibility, neutron, and x-ray diffraction measurements on polycrystalline UAu2Si2. Magnetic susceptibility data show the existence of two phases below 50 K. Since no superlattice neutron peaks were observed within the sensitivity of the apparatus we conclude that the system is not a canted ferromagnet, as was suggested earlier. On the basis of the temperature dependence of the neutron and x-ray intensity we discuss a possibility that UAu2Si2 undergoes two structural phase transitions, at 48 and at 18 K and that these transitions are correlated with the magnetic state of the material.