In-Plane and Out-of-Plane Optical Properties of NdBa2Cu3Ox Single Crystals close to x = 7.0

TL;DR

This study investigates the optical properties of NdBa2Cu3Ox single crystals near full oxygen doping, revealing anisotropic features and suggesting electron-spin scattering as a common mechanism for observed anomalies.

Contribution

It provides detailed measurements of in-plane and out-of-plane optical properties near x=7.0, highlighting the role of electron-spin interactions in these materials.

Findings

Presence of a 450 cm^-1 absorption band along the c-axis.

In-plane excitations include a 400 cm^-1 step and a 500-550 cm^-1 feature.

Correlation between optical conductivity and neutron scattering spectra suggests electron-spin scattering mechanism.

Abstract

We present results of reflectivity measurements with E parallel to c and E perpendicular to c on NdBa2Cu3Ox (Nd123) single crystals close to full oxygen doping. Along the c-axis the optical conductivity shows a well developed absorption band around 450 cm^-1 at all temperatures. The in-plane optical properties are dominated by crystal-field excitations at low energies, a prominent step at 400 cm^-1 and a weaker feature between 500 - 550 cm^-1. A comparison of the c-axis optical conductivity and the in-plane scattering rate 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.