Electrical Resistivity near the Magnetic Transition of Some Rare-Earth Laves Phase Compounds

Abstract

From the measured temperature dependence of the electrical resistivity $\rho \mathrm{}\left(T\right)\mathrm{}$, we have computed the temperature derivative $\frac{d\rho }{\mathrm{dT}}$ with particular emphasis on its behavior in the critical region for six ferromagnetic rare-earth cubic Laves phase compounds: Gd${\mathrm{Al}}_2$, Gd${\mathrm{Co}}_2$, Gd${\mathrm{Ni}}_2$, Gd${\mathrm{Pt}}_2$, Gd${\mathrm{Rh}}_2$, and Dy${\mathrm{Al}}_2$. All samples are characterized by pronounced changes in $\frac{d\rho }{\mathrm{dT}}$ in the vicinity of the magnetic ordering temperature $T_c$. In Gd${\mathrm{Ni}}_2$, Gd${\mathrm{Pt}}_2$, and Gd${\mathrm{Rh}}_2$, as the temperature is decreased toward $T_c$, a minimum in $\frac{d\rho }{\mathrm{dT}}$, followed by a maximum, is observed. This behavior is consistent with that predicted from the long-range nature of the short-range spin fluctuations in the framework of the molecular field theory. The behavior of $\frac{d\rho }{\mathrm{dT}}$ for Gd${\mathrm{Al}}_2$ and Dy${\mathrm{Al}}_2$ shows only a broad maximum, whereas for Gd${\mathrm{Co}}_2$, $\frac{d\rho }{\mathrm{dT}}$ has a sharp peak at about $T_c$ — very similar to that found in transition metals.