Magnetic properties of the filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 synthesized under high pressure

We have succeeded in synthesizing Filled skutterudite-type structure compou nds GdRu4P12 and TbRu4P12 under high pressure. The magnetic properties of G dRu4P12 and TbRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, and magnetization measurements. Magnetic experimen ts suggest that the Gd and Tb ions in the compounds have trivalent state. T he compound GdRu4P12 displays features that suggest the occurrence of antif erromagnetic ordering below T-N=22 K. In TbRu4P12, thermal variation of mag netic susceptibility indicates the existence of two successive magnetic tra nsitions (T-N=20 K and T-1 = 10 K). Magnetization up to 18 T exhibits two-s tep metamagnetic transitions below T1 for TbRu4P12.