Enhanced electrical resistivity before Néel order in the metals RCuAs2 (R=Sm, Gd, Tb, and Dy).

We report an unusual temperature (T) dependent electrical resistivity (p) behavior in a class of ternary intermetallic compounds of the type RCuAs 2 (R = rare earths). For some rare earths (Sm, Gd, Tb, and Dy) with negligible 4f hybridization, there is a pronounced minimum in p(Tj far above respective Neel temperatures (T N ). However, for the rare earths which are more prone to exhibit such a p(T) minimum due to 4f-covalent mixing and the Kondo effect, this minimum is depressed. These findings, difficult to explain within the hitherto-known concepts, present an interesting scenario in magnetism.