Photopyroelectric Surface Reflectance Spectra of Pr_2−xCe_xCuO₄ Single Crystals

Abstract

Surface reflectance spectra of Pr_2−xCe_xCuO₄ (x:0; 0.025; 0.075) single crystals in the photon energy range 0.5-3 eV were determined by the photopyroelectric (PPE) technique from direct measurements of absorptance. PPE reflectance spectroscopy allows a better resolution of the structural shape of the spectra. The main spectral features of the Pr₂CuO₄ reflectance are a peak around 1.45 eV and two shoulders (around 1.1 eV and 1.85 eV). The reflectivity peak is strongly reduced even for low level of Ce doping (x:0.025) although it can still be seen as a sharp peak with the maximum around 1.5 eV. The metallic Drude-like behavior, which appears already for x:0.025, becomes evident at x=0.075, with a clear reflectivity edge around 1.05 eV.

Key Words:

• photopyroelectric spectroscopy
• reflectivity of Pr_2−xCe_xCuO₄ (x:0; 0.025; 0.075)