Superconducting Pr2CuOx, x≃4 (PCO) films with T′ structure and a Tc of 27 K have been investigated by various optical methods in a wide frequency (7 - 55000 cm−1) and temperature (2 to 300 K) range. The optical spectra do not reveal any indication of a normal-state gap formation. A Drude-like peak centered at zero frequency dominates the optical conductivity below 150 K. At higher temperatures, it shifts to finite frequencies. The detailed analysis of the low-frequency conductivity reveals that the Drude peak and a far-infrared (FIR) peak centered at about 300 cm−1 persist at all temperatures. The FIR-peak spectral weight is found to grow at the expense of the Drude spectral weight with increasing temperature. The temperature dependence of the penetration depth follows a behavior typical for d-wave superconductors. The absolute value of the penetration depth for zero temperature is 1.6 μm, indicating a rather low density of the superconducting condensate.
@article{arxiv.1406.7258,
title = {Optical study of superconducting Pr$_2$CuO$_{x}$ with $x\simeq 4$},
author = {G. Chanda and R. P. S. M. Lobo and E. Schachinger and J. Wosnitza and M. Naito and A. V. Pronin},
journal= {arXiv preprint arXiv:1406.7258},
year = {2014}
}