Non-Fermi liquid behavior and scaling of the low-frequency suppression in the optical conductivity spectra of ${\mathrm{CaRuO}}_3$

Optical conductivity spectra ${\sigma }_1\left(\omega \right)$ of paramagnetic ${\mathrm{CaRuO}}_3$ are investigated at various temperatures. At $T=10\mathrm{}\hspace{0.5em}\mathrm{K},$ it shows a non-Fermi-liquid behavior of ${\sigma }_1\left(\omega \right)\sim 1/{\omega }^{1/2},$ similar to the case of a ferromagnet ${\mathrm{SrRuO}}_3.$ As the temperature (T) is increased, on the other hand, ${\sigma }_1\left(\omega \right)$ in the low-frequency region is progressively suppressed, deviating from the $1/{\omega }^{1/2}$ dependence. Interestingly, the suppression of ${\sigma }_1\left(\omega \right)$ is found to scale with $\omega /T$ at all temperatures. The origin of the $\omega /T$ scaling behavior coupled with the non-Fermi-liquid behavior is discussed.