Magnetic behaviour of TbCu4Ag and DyCu4Ag

Abstract The temperature dependences of DC and AC magnetisation, electrical resistivity and magnetoresistivity of TbCu4Ag and DyCu4Ag are reported. In contrast to previous studies which indicate TbCu4Ag to be a simple antiferromagnet and DyCu4Ag to be a ferromagnet, our study indicates a more complicated behaviour for these materials. We observe three magnetic transitions for TbCu4Ag, viz. at TC=20 K, T1=11 K and T2=2.5 K. At temperatures T⩽ 10 K the magnetic isotherms show metamagnetic behaviour, while for T1⩽T⩽TC our results suggest canted antiferromagnetism. For DyCu4Ag magnetic transitions are observed at TC=19 K and in the vicinity of 5 K. Also for this material there is evidence suggesting a canted antiferromagnetic spin structure.