Magnetic ground states of CeTiSb, PrTiSband NdTiSbdetermined by neutron powder diffraction and magnetic measurements.

TheTiSbternary compounds, witha light rare earth (La to Sm) have been reported to crystallize with the anti-HfCuSn-type hexagonal structure (Pearson's symbol18; space-group6/, N. 193). An early article that reported possible superconductivity in some of these intermetallic phases (namely those with= La, Ce, and Nd) caught our attention. In this work, we have now refined the crystal structure of theTiSbcompounds with= Ce, Pr and Nd by Rietveld methods using high-resolution neutron powder diffraction data. The magnetic ground states of these intermetallics have been investigated by low-temperature magnetization and high-intensity neutron diffraction. We find two different magnetic transitions corresponding to two related magnetic structures at= 4.8 K (= [0, 1/2, 1/8]) and= 3.4 K (= [0, 0, 1/8]), respectively for CeTiSb. However, the magnetic ordering appears to occur following a peculiar hysteresis: the-type magnetic structure develops only after the-type phase fraction has first slowly ordered with time and the size of the ordered Cemagnetic moment has become large enough to induce the second magnetic transition. At= 1.5 K the maximum amplitude of the Ce moment in the coexisting phases amounts to= 2.15 . For NdTiSban antiferromagnetic ordering below= 5.2 K into a relatively simpler commensurate magnetic structure with a magnetic moment of= 2.14(3)and magnetic propagation vector of= [0, 0, 0], was determined. No evidence of superconductivity has been found in NdTiSb. Finally, PrTiSbdoes not show any ordering down to 1.5 K in neutron diffraction while an antiferromagnetic ground state is detected in magnetization measurements. There is no sign of magnetic contribution from Ti atoms found in any of the studied compounds.