Direct experimental estimations of the low-energy (1.5-10 meV) complex diel
ectric constants spectrum and its temperature variation have been investiga
ted for La0.7Ca0.3MnO3 thin films using terahertz time-domain spectroscopy.
At low temperatures, a clear Drude term emerges. With increasing temperatu
re, the scattering rate increases, while the plasma frequency decreases, bo
th derived from a simple Drude model. Finally, a Drude term submerges well
below the insulator-metal transition temperature. On the basis of the prese
nt results, low-energy charge dynamics are discussed.