Long-range magnetic order in intermediate-valence CeLu alloys

The magnetic ordering in CeLu alloys has been studied using neutron diffraction, and the electronic state of the Ce has been determined using X-ray magnetic resonant scattering (XMRS). CeLu orders with the same magnetic structure as CeY, but the temperature dependence of the order parameter is different and the average saturated moment on the Ce sites is lower. The diffuse neutron magnetic scattering observed in other Ce alloys is not observed for CeLu, and this implies that this unusual scattering originates from the competition between exchange and dipolar interactions. The XMRS results show that the Ce in CeLu alloys has an intermediate valence, and the results suggest that this behaviour is due to chemical pressure. (orig.)