Magnetic ordering in ternary germanide Nd2CuGe6

We have performed a systematic investigation on a well-annealed polycrystalline Nd2CuGe6 sample by measuring its AC and DC susceptibility χ(T), magnetization M(H), magnetic relaxation M(t), electrical resistivity ρ(T) and specific heat C(T). The sharp peak observed at about TN = 9.4 K in χAC(T), χDC(T) and C(T) curves, respectively, indicates the occurrence of an antiferromagnetic order, which is further confirmed by the sudden decrease in ρ(T) at the same temperature. In the magnetically ordered state, M(H) shows an evident metamagnetic transition. Moreover, the χDC(T) and M(t) measurements reveal evident irreversible magnetism and long-time magnetic relaxation effect below TN indicating the metastable characters of the magnetically ordered state. The formation of the metastable magnetic state cannot be explained as glass freezing of the neodymium magnetic moments in the Ce2CuGe6-type orthorhombic Nd2CuGe6 sample.