Magnetic structures of RNiSb compounds (R=rare earths) investigated by neutron diffraction

The magnetic structures of RNiSb compounds (R = Ce, Nd, Tb, Dy, Ho) have been investigated by neutron diffraction. At low temperatures, the hexagonal compound NdNiSb shows a ferromagnetic order, whereas CeNiSb has a modulated structure with a ferromagnetic component. The cubic compounds Tb-, Dy-, and HoNiSb order antiferromagnetically with a propagation vector Q = (0.5, 0.5, 0.5). In the latter semiconducting phases, negative superexchange interactions between nearest neighbours should dominate. The crystal electric field plays an important role in all compounds. (C) 1998 Elsevier Science B.V. All rights reserved.