Magnetic properties and magnetic phase diagrams of trigonal DyNi₃Ga₉

We report the crystal structure, magnetic properties, and magnetic phase diagrams of single crystalline DyNi₃Ga₉ studied using X-ray diffraction, electrical resistivity, specific heat, and magnetization measurements. DyNi₃Ga₉ crystallizes in the chiral structure with space group R32. The dysprosium ions, which are responsible for the magnetism in this compound, form a two-dimensional honeycomb structure on a (0001) plane. We show that DyNi₃Ga₉ exhibits successive phase transitions at T_N = 10K and T_N⁰ ¼ 9K. The former suggests quadrupolar ordering, and the latter is attributed to the antiferromagnetic order. It is considered that DyNi₃Ga₉ forms the canted-antiferromagnetic structure below T_N⁰ owing to a small hysteresis loop of the low-field magnetization curve. We observe the strong easy-plane anisotropy, and the multiple-metamagnetic transitions with magnetization-plateaus under the field applied along the honeycomb plane. For H k ½2110 , the plateau-region arises every 1=6 for saturation magnetization. The magnetic phase diagrams of DyNi₃Ga₉ are determined for the fields along principal-crystal axes.