Optical conductivity of Pr2CuO4 in the terahertz range

Recently, it has been shown that nominally undoped Pr2CuO4 can become superconducting, being grown in form of thin films with T' structure. We have measured the temperature and frequency-dependent complex transmission coefficient of these films at terahertz frequencies. From the measured spectra, we have directly calculated the complex optical conductivity. Both components of the conductivity demonstrate a behavior typical for the HTS cuprates. The stiffness of the superconducting condensate is, however, quite low, leading to a large value of the London penetration depth (1.8 μm). We discuss our results in comparison with literature data on terahertz properties of other HTS.