MAGNETISM OF TERNARY STANNIDES RCUSN (R=GD-ER)

The magnetic properties of RCuSn (R=Gd + Er) phases, including their m agnetic structures, were studied using polycrystalline samples. The ti tle compounds show the hexagonal, LiGaGe-type of structure and are ant iferromagnetic at low temperatures. At 1.5 K TbCuSn and HoCuSn exhibit colinear anti-ferromagnetic order described by the wavevector k=(1/2, 0, 0) which at 12.6 and 5.8 K respectively, transforms into incommens urate magnetic structures with k=(0.445, 0, 0) in TbCuSn and k=(0.430, 0.035, 0) in HoCuSn. The colinear anti-ferromagnetic structure was al so detected at 1.5 K in DyCuSn. It was found to be stable up to the Ne el point at 5 K. The angle between the magnetic moment and the hexagon al axis is 90 degrees in TbCuSn, 44.6 degrees in DyCuSn and 0 degrees in HoCuSn.Two wave-vectors k(1) =(1/3, 0, 0) and k(2) =(0.392, 0.05, 0 ) describe the magnetic order at 1.5 K in ErCuSn. Strong magnetic refl ections due to the k(1) structure fall to zero at the Neel point at 4. 7 K, while the much weaker magnetic peaks representing the k(2) struct ure vanish at 3 K. Ac magnetic susceptibility vs temperature curves we re recorded indicating the transition temperatures to be in fair accor dance with neutron diffraction data. Magnetization vs temperature plot s were obtained in the presence of small strength magnetic fields; mag netic susceptibility and reciprocal susceptibility versus temperature curves were also obtained. Magnetization against applied magnetic fiel ds (up to 50 kOe) curves show the presence of metamagnetic transitions in a number of the title compounds. Resistivity data obtained for all title compounds indicate their metallic-like conductivity. (C) 1997 E lsevier Science S.A.