Magnetism of ternary stannides RCuSn (R=Gd-Er)

The magnetic properties of RCuSn (R=Gd + Er) phases, including their magnetic structures, were studied using polycrystalline samples. The title compounds show the hexagonal, LiGaGe-type of structure and are antiferromagnetic 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 incommensurate 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 also detected at 1.5 K in DyCuSn. It was found to be stable up to the Neel point at 5 K. The angle between the magnetic moment and the hexagonal 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 reflections 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) structure vanish at 3 K. Ac magnetic susceptibility vs temperature curves were recorded indicating the transition temperatures to be in fair accordance with neutron diffraction data. Magnetization vs temperature plots were obtained in the presence of small strength magnetic fields; magnetic susceptibility and reciprocal susceptibility versus temperature curves were also obtained. Magnetization against applied magnetic fields (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 Elsevier Science S.A.