Magnetic properties of NdTX (T=Cu, Ag, Au; X=Sn, Pb) compounds

Abstract

Abstract We report SQUID magnetometry studies of the susceptibility of NdTX (T=Cu, Ag, Au; X=Sn, Pb) compounds in the temperature range 5 K ⩽T⩽300 K and the field range 0.5 Oe ⩽H⩽50.000 Oe. The susceptibility curves, χ(T), for all samples except NdCuSn, exhibit a sharp peak at the Neel temperature, TN. The analysis of χ(T) in the paramagnetic region by using Curie–Weiss law enables us to determine the magnetic moments localized on Nd ions μeff, the Curie paramagnetic temperature θP and the temperature-independent susceptibility χ0. Oscillatory behaviour has been observed in low-field χ(T) versus 1/T for NdCuPb and NdAgPb, from which results suggest a helical antiferromagnetic ordering probably due to an exchange interaction of RKKY-type and crystalline field effects. We also find that superconductivity and antiferromagnetism coexist at the temperatures below T∼7 K for the samples including Pb.