Energy scales ofLu1−xYbxRh2Si2by means of thermopower investigations

Abstract

We present the thermopower $S(T)$ and the resistivity $\ensuremath{\rho}(T)$ of ${\mathrm{Lu}}_{1\ensuremath{-}x}{\mathrm{Yb}}_{x}{\mathrm{Rh}}_{2}{\mathrm{Si}}_{2}$ in the temperature range $3lTl300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. $S(T)$ is found to change from two minima for dilute systems $(xl0.5)$ to a single large minimum in pure $\mathrm{Yb}{\mathrm{Rh}}_{2}{\mathrm{Si}}_{2}$. A similar behavior has also been found for the magnetic contribution to the resistivity ${\ensuremath{\rho}}_{\mathrm{mag}}(T)$. The appearance of the low-$T$ extrema in $S(T)$ and ${\ensuremath{\rho}}_{\mathrm{mag}}(T)$ is attributed to the lowering of the Kondo scale ${k}_{B}{T}_{K}$ with decreasing $x$. The evolution of the characteristic energy scales for both the Kondo effect and the crystal electric field splitting ${\ensuremath{\Delta}}_{\mathrm{CEF}}$ are deduced. An extrapolation of ${T}_{K}$ to $x=1$ allows us to estimate the Kondo temperature of $\mathrm{Yb}{\mathrm{Rh}}_{2}{\mathrm{Si}}_{2}$ to $29\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. For pure $\mathrm{Yb}{\mathrm{Rh}}_{2}{\mathrm{Si}}_{2}$, ${T}_{K}$ and ${\ensuremath{\Delta}}_{\mathrm{CEF}}∕{k}_{B}$ lie within one order of magnitude and thus the corresponding extrema merge into one single feature.