Test of Fermi-liquid theory in MnSi with terahertz conductivity measurements

We describe time-domain terahertz spectroscopy measurements of the frequency-dependent conductivity in MnSi thin films. We find that at low temperatures and frequencies, the scattering rate is proportional to both the square of the temperature and the square of the frequency, as predicted Fermi liquid theory. Unlike measurements on many other systems, the prefactors for each functional dependence are also consistent with the theory.