Neutron diffraction study of magnetic ordering in RAgSn (R=Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er) compounds

Neutron diffraction study of RAgSn compounds has shown that most of them exhibit at 1.6 K a collinear antiferromagnetic order described by the wave vector k = \1/2, 0, 0\ in a hexagonal structure derived from the LiGeGa-type crystal structure. The magnetic moment is normal to the c-axis in CeAgSn, it is inclined at an angle of 40 degrees to the c-axis in DyAgSn and is parallel to the c-axis in the remaining compounds. In PrAgSn, a sine modulated magnetic structure with the wave vector k = \1/3, 1/3, 0\ and moments along the c-axis has been found between T = 1.6 K and T-N = 3.6 K. Incommensurate sine modulated magnetic structures have been observed near the Ni el points at 10.2 and 5.6 K in HoAgSn and ErAgSn, respectively. The magnitudes of magnetic moments at 1.6-1.9 K and the Neel points were determined from neutron diffraction data. Supplementary magnetization and magnetic susceptibility measurements were carried out for all RAgSn compounds including GdAgSn. The latter was found to order magnetically below T-N = 34 K.