Anisotropic Optical Conductivity of Nd_2-xCe_xCuO₄ Thin Films

Abstract

Opticcal conductivity spectra $\\sigma_1(\\omega)$ of Nd2-xCexCuO4 thin films,\nmeasured by the reflectance-transmittance method (R-T method) which has been\nproposed to investigate far-infrared spectroscopy, are investigated based on\nthe anisotropic pairing model. Precise measurements of the frequency-dependent\nconductivity enable us to examine quantitatively the nature of the\nsuperconducting gap through infrared properties in the electron-doped high-Tc\nsuperconductors. We show that the behavior of optical conductivity $\\sigma_1$\nis consistent with the anisotropic superconducting gap and is well explained by\nthe formula for d-wave pairing in the low-energy regime of the far-infrared\nregion. Our results suggest that the electron-doped cuprate superconductors\nNd2-xCexCuO4 have nodes in the superconducting gap.\n