Low-energy charge dynamics in La0.7Ca0.3MnO3: THz time-domain spectroscopic studies

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.