In-plane terahertz response of thin filmSr2RuO4

The low-energy electron dynamics of the quasi-two-dimensional electron-hole multiorbital system ${\mathrm{Sr}}_{2}\mathrm{Ru}{\mathrm{O}}_{4}$ is investigated by time-domain terahertz spectroscopy for a thin film sample. The direct observation of the real and imaginary part of the optical conductivity below 8 meV clearly demonstrates a narrowing of the coherent quasiparticle response with decreasing temperature. The optical conductivity spectra, dc conductivity, and Hall coefficient can be quantitatively well described by the multiband Drude-Lorentz model, from which band dependent scattering rates can be extracted. The resulting modest band dependent scattering rates, which are lower than 2 meV at 4 K, support a rather isotropic relaxation regime.