Anisotropic optical conductivity of Nd_{2-x}Ce_xCuO_4 thin films

Abstract

Optical conductivity spectra \sigma_1(\omega) of Nd_{2-x}Ce_xCuO_4 thin films, measured by the reflectance-transmittance (R-T) method which has been proposed to investigated far-infrared spectroscopy, are investigated based on the anisotropic pairing model. Precise measurements of the frequency-dependent conductivity \sigma_1(\omega) enable us to examine quantitatively the nature of the superconducting gap through infrared properties for the first time in high-Tc superconductors. We show that the behavior of optical conductivity \sigma_1(\omega) is consistent with the anisotropic superconducting gap and is well explained by the formula for d-wave pairing in the far-infrared region. Our results suggest that the electron-doped cuprate superconductors Nd_{2-x}Ce_xCuO_4 have nodes in the superconducting gap.


Article outline

1.Introduction
2.Theory and Measured Conductivity
3.Summary