A neutron diffraction study of the hexagonal Laves phases, Ho(Co0.667Ga0.333)2 and Er(Co0.667Ga0.333)2: Co/Ga site preferences and magnetic structure

RE(Co0.667Ga0.333)2 (RE = Ho, Er) were characterized by neutron powder diffraction (NPD). Rietveld refinement of the NPD data at 280K confirms the hexagonal MgZn2-type structure (P63 /mmc), in accordance with the previous XRD results. Co/Ga occupancies on the 2a and 6h sites were refined to be 0.46/0.54(2) and 0.74/0.26(2), respectively, indicating a preference of Ga for the 2a site and of Co for the 6h site. Both materials are ferromagnetic, k …