Antiferromagnetism in Pr3 In

We present neutron diffraction, magnetic susceptibility and specific heat data for a single-crystal sample of the cubic (Cu3 Au structure) compound Pr3 In. Antiferromagnetic order occurs below TN =12 K with propagation vector (0,0,0.5±δ) where δ 1 12. The neutron diffraction results can be approximated with a model where the moments in each of the three Pr sublattices form ferromagnetic sheets perpendicular to and alternating in sign along the propagation direction, with a 12-unit-cell square-wave modulation. The very small specific heat anomaly that we observe at TN =12 K may be a consequence of the fact that the ordered moment is induced in the Γ1 singlet when T< TN. The magnetic susceptibility indicates that in addition to the antiferromagnetic transition at 12 K, there may be a transition near 70 K below which there is a very small remnant magnetization (0.005 μB).