Enhanced electrical resistivity before N\'eel order in the metals, RCuAs$_2$ (R= Sm, Gd, Tb and Dy

Abstract

We report an unusual temperature (T) dependent electrical resistivity($\rho$) 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 $\rho$(T) far above respective N\'eel temperatures (T$_N$). However, for the rare-earths which are more prone to exhibit such a $\rho$(T) minimum due to 4f-covalent mixing and the Kondo effect, this minimum is depressed. These findings, difficult to explain within the hither-to-known concepts, present an interesting scenario in magnetism.Comment: Physical Review Letters (accepted for publication