Magnetic and transport anomalies in the compounds, RCuAS2 (R = Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

The results of DC magnetization, heat capacity, electrical resistivity (p) and magnetoresistance measurements are reported in detail for the compounds, RCuAs2 for R = Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, crystallizing in HfCUSi2-type tetragonal structure, with the aim of bringing out anomalies among 'normal' (that is, other than Cc and Yb) rare-earths. The results establish that all these compounds order antiferromagnetically at low temperatures with deviations from de Gennes scaling. Isothermal magnetization (M) data below respective Neel temperatures (T-N) reveal the existence of field-induced metamagnetic-like transitions for most of the compounds (except R = Sin and Gd), whereas in Sm and Gd compounds M varies essentially linearly with magnetic field. With respect to the rho behavior, there appears to be a subtle difference in the temperature dependence beyond 50 K between Sin on the one hand and the rest on the other. In addition, the unexpected p(T) minimum reported recently for R = Sm, Gd, Th and Dy in the paramagnetic state (around 20-30 K) is essentially absent for R = Ho and Er. The results overall reveal that the normal rare-earths in this series present an interesting situation in magnetism, warranting a new theoretical approach to describe the transport behavior in the paramagnetic state particularly in the vicinity of TN. (C) 2004 Elsevier B.V. All rights reserved.