Anomalous transport properties ofRFe4P12(R= La, Ce, Pr, and Nd)

Abstract

We have investigated the resistivity $\left(\rho \right),$ thermoelectric power (TEP), and Hall coefficient ${(R}_H)$ on high-quality single crystals of $R{\mathrm{Fe}}_4{\mathrm{P}}_{12}.$ TEP in ${\mathrm{CeFe}}_4{\mathrm{P}}_{12}$ is extremely large $(\sim 0.5$ mV/K at 290 K) with a peak of $\sim 0.75$ mV/K at around 65 K. The Hall mobility also shows a peak at $\sim 65$ K, suggesting carriers with heavy masses developed at lower temperatures related to the f-hybridized band. Both Pr and Nd systems exhibit an apparent increase of $\rho$ with decreasing temperature far above their magnetic transition temperatures. In the same temperature ranges, TEP exhibits unusually large absolute values of $-50\hspace{0.5em}\mu \mathrm{V}/\mathrm{K}$ for ${\mathrm{PrFe}}_4{\mathrm{P}}_{12}$ and $-15\hspace{0.5em}\mu \mathrm{V}/\mathrm{K}$ for ${\mathrm{NdFe}}_4{\mathrm{P}}_{12},$ respectively. For ${\mathrm{PrFe}}_4{\mathrm{P}}_{12},$ such anomalous transport properties suggest an unusual ground state, possibly related to the quadrupolar Kondo effect.