ELLIPSOMETRIC MEASUREMENT OF THE DIELECTRIC TENSOR OF ND2-XCEXCUO4-DELTA

We study the anisotropic optical properties of a superconducting singl e crystal of Nd2-xCexCuO4-delta (x similar or equal to 0.16). The two components of the dielectric tensor and its orientation with respect t o the sample surface are obtained by analysis of ellipsometric data me asured at room temperature from 1.4 to 5.1 eV. The optical anisotropy originates in the different spectral behavior of these two components. The ordinary dielectric function, which is related to the copper-oxyg en planes, exhibits metallic character. The extraordinary component, r elated to excitations along the c axis, is nonmetallic and rather feat ureless.