Magnetization, electrical resistivity and neutron diffraction studies of the U2(Ni1-xPtx)2In system

Abstract

X-ray powder diffraction, magnetization, electrical resistivity and neutron diffraction experiments were performed on the dense Kondo system U2(Ni1-xPtx)2In. Up to x0.5 the alloys crystallize in a tetragonal structure with space group P4/mbm while for x0.6 they crystallize in space group P42/mnm. The observed structural change coincides with the magnetic-nonmagnetic crossover in the system. In the concentration range 0 x0.5, an antiferromagnetic ordering occurs, characterized by a noncollinear arrangement of the magnetic uranium moments in the tetragonal basal plane. In addition, for x = 0 and 0.2 a commensurate magnetic ordering is formed with a propagation vector k = (0,0,0.5) while for x = 0.5 an incommensurate one with k = (0,0,0.5±), = 0.06 is found. In the concentration range 0.6 x1.0 no magnetic ordering down to 1.7 K is observed. The bulk and neutron scattering data exhibit features attributed to the interplay of the Kondo effect and magnetic exchange interactions. For interpretation of the magnetic behaviour of the U2(Ni1-xPtx)2In alloys, a strong modification of the density of states at the Fermi surface has been invoked.