Fig. 4.

Temperature dependence of the resistivity of ${\mathrm{Y}\mathrm{b}\mathrm{R}\mathrm{u}}_2{\mathrm{G}\mathrm{e}}_2$. The resistivity (purple data points) and its derivative with respect to temperature (green data points) show clear features at $T_Q$ (marked by a vertical dashed line), as well as $T_{N1}$ and $T_{N2}$. Slight differences in estimates of the critical temperatures relative to values extracted from X-ray diffraction measurements are attributed to differences in sweep rates of the two measurements. Inset shows the resistivity over a larger temperature range, in which a different ${\mathrm{Y}\mathrm{b}\mathrm{R}\mathrm{u}}_2{\mathrm{G}\mathrm{e}}_2$ single crystal is measured. Data are also shown for the nonmagnetic analog, ${\mathrm{Y}\mathrm{R}\mathrm{u}}_2{\mathrm{G}\mathrm{e}}_2$, for which no phase transitions are observed. Yttrium has an empty $4f$ shell but otherwise the electronic structure of the two materials is anticipated to be very similar, and differences in the resistivity between the two compounds are primarily attributed to $4f$ scattering.