Evolution of magnetic structures in the UNi 2 Si 2 -UPd 2 Si 2 system

The influence of Pd-Ni substitution on the formation of magnetic phases in the tetragonal U(Ni1-x, Pdx)2Si2 system and the concentration magnetic phase diagram are presented. A series of different substitutions was prepared and detailed studies by powder neutron diffraction were performed for x=0.25, 0.5 and 0.75. All compounds order antiferromagnetically and form ferromagnetic basal planes stacked along the c axis (q=(0,0,qz) propagation). The ground-state phase (AF3) of UNi2Si2 is an uncompensated AF structure (++- stacking (qz=2/3)). In UPd2Si2 the ground-state phase corresponds to the simple AF structure AF2 (+-+-(qz=1)). In solid solutions, no traces of the AF3 phase were found for x=0.25 and the ground-state powder patterns correspond to AF2 for x≥0.25.