Applying the extended Drude model for the mid-infrared complex conductivity tensor of SrRuO$_3$

The complex longitudinal ($\sigma_{xx}$) and Hall ($\sigma_{xy} $) conductivities in a SrRuO$_3$ film are determined using Faraday and Kerr measurements in the mid-infrared (100 $\sim$ 1000 meV) energy and 10 K $\sim$ 300 K temperature ranges. The extended Drude model (EDM) for ($\sigma_{xx}$) is used to subtract the ordinary part of $\sigma_{xy}$. Using the EDM parameters, the ordinary contribution to $\sigma_{xy}$ is found to be significantly smaller than the anomalous contribution at most temperatures and wavelengths, decreasing strongly as the wavelength decreases. We suggest that the paramagnetic part of the $\sigma_{xy}$ results from the unsaturated magnetization, not from the ordinary part of $\sigma_{xy}$. This work was supported by the Research Crop. Cottrell Scholar Award (UB), NSF-CAREER-DMR0449899 (UB), and an instrumentation award from the CAS (UB). Oak Ridge Natl. Lab. Is managed by UT- Battelle, LLC, for the U.S. DOE (contract DE-ACO5-00OR22725).