Terahertz spectroscopy of superconductors in high magnetic fields

We report on measurements of the complex conductivity of cuprate superconductors at terahertz frequencies in fields up to 10 T. High-quality films of La2-xCexCuO4 and La2-xEuxCuO4 with different doping levels on transparent substrates have been used for our investigations. The measurements have been performed in the transmission mode. We discuss the behavior of the complex conductivity as a function of temperature, frequency, and magnetic field. We have found a small but distinctive optical magnetoresistance. We also realized some signatures of the pseudogap in the terahertz spectral range in magnetic field.