Neutron-diffraction studies of single crystals of U2T2In (T=Ni, Pd, Pt)

Neutron-diffraction experiments on single crystals of U2T2In (T = Ni, Pd, P t) verify the noncollinear magnetic structures found with studies of polycr ystalline samples, and determine the values of the ordered moments. Compare d to the earlier studies, we find the ordered moments on the uranium atoms larger, and no moment associated with the T atoms, in disagreement with one previous study. The T = Pt sample has a large electronic specific heat and does not order magnetically. We give a detailed description of the low-tem perature crystal structure. Polarized-neutron experiments show that the sit e susceptibilities of the two independent uranium atoms in U2Pt2In are subs tantially different and the conduction-electron polarization is unusually l arge. [S0163-1829(99)00118-6].