In–Plane and Out–of–Plane Optical Properties of NdBa2Cu3Ox Single Crystals Close to x = 7.0

We present results of reflectivity measurements withE∥candE ⊥ con NdBa2Cu3Ox(Nd123) single crystals close to full oxygen doping. Along the c–axis the optical conductivity\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\sigma _1^c $$ \end{document}shows a well developed absorption band around 450 cm−1at all temperatures. The in–plane optical properties are dominated by crystal–field excitations at low energies, a prominent step at 400 cm−1and a weaker feature between 500 - 550 cm−1. A comparison of\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\sigma _1^c $$ \end{document}and the in–plane scattering rate Γab(ω) with neutron scattering derived spin susceptibility spectra suggests that the in–plane and out–of–plane anomalies are caused by the same mechanism, probably electron–spin scattering.