Non-Fermi-Liquid Behavior ofSrRuO3: Evidence from Infrared Conductivity

The reflectivity of the itinerant ferromagnet $\mathrm{SrRuO}{}_3$ has been measured between 50 and 25 000 $\mathrm{cm}{}^{-1\mathrm{}}$ at temperatures ranging from 40 to 300 K, and used to obtain conductivity, scattering rate, and effective mass as a function of frequency and temperature. We find that at low temperatures the conductivity falls unusually slowly as a function of frequency (proportional to $1/{\omega }^{1/2}$), and at high temperatures it even appears to increase as a function of frequency in the far-infrared limit. The data suggest that the charge dynamics of $\mathrm{SrRuO}{}_3$ are substantially different from those of Fermi-liquid metals.