X-ray scattering study of the magnetic phase transformation in GdB6

Abstract

Gadolinium hexaboride is thought to have at least two magnetic phases in zero magnetic field. The structure of these phases, however, is still unknown. Due to the high neutron absorption of both Gd and B, studies by neutron scattering are not easy to do. We therefore used the alternative technique of x-ray magnetic scattering. Experiments were performed with a rotating anode x-ray source and CuKα radiation at temperatures down to 6 K. At the lowest temperatures two sets of superlattice reflections of the form (h/2,k,l) and/or (h,k/2,l) and (h/2,k/2,l) were observed. The intensity of both types of reflection remains roughly constant until 10 K. At this temperature the intensities of the (h/2,k,l) and (h,k/2,l) reflections increase sharply and reach a maximum around 11.5 K, while the (h/2,k/2,l) reflections rapidly disappear. At 12 K, only the former reflections are observed and they disappear discontinuously at TN =15.85±0.5 K. The results confirm the existence of two magnetic phase transitions in GdB6 and suggest a complex multi-q magnetic structure.