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

Abstract

We report an unusual temperature (T) dependent electrical resistivity (ρ) behavior in a class of ternary intermetallic compounds of the type RCuAs₂ (R=rare earths). For some rare earths (Sm, Gd, Tb, and Dy) with negligible 4f hybridization, there is a pronounced minimum in ρ(T) far above respective Néel temperatures (T_N). However, for the rare earths which are more prone to exhibit such a ρ(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.