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 th em exhibit at 1.6 K a collinear antiferromagnetic order described by t he wave vector k = \1/2, 0, 0\ in a hexagonal structure derived from t he 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-a xis 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 stru ctures have been observed near the Ni el points at 10.2 and 5.6 K in H oAgSn 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 measure ments were carried out for all RAgSn compounds including GdAgSn. The l atter was found to order magnetically below T-N = 34 K.