In-Plane Spectral Weight Shift of Charge Carriers in $YBa_2Cu_3O_{6.9}$

TL;DR

This study investigates how the spectral weight of charge carriers in YBa2Cu3O6.9 shifts with temperature, revealing a high-energy scale transfer associated with superconductivity and changes in optical self-energy.

Contribution

It provides new insights into the high-energy spectral weight transfer and optical self-energy evolution in a high-temperature superconductor using wide-band spectroscopic ellipsometry.

Findings

Superconductivity induces a spectral weight transfer exceeding 1 eV.

Charge carrier spectral weight decreases in the superconducting state.

Detailed evolution of optical self-energy across phases was observed.

Abstract

The temperature dependent redistribution of the spectral weight of the $CuO_2$ plane derived conduction band of the $YBa_2Cu_3O_{6.9}$ high temperature superconductor (T_c = 92.7 K) was studied with wide-band (from 0.01 to 5.6 eV) spectroscopic ellipsometry. A superconductivity - induced transfer of the spectral weight involving a high energy scale in excess of 1 eV was observed. Correspondingly, the charge carrier spectral weight was shown to decrease in the superconducting state. The ellipsometric data also provide detailed information about the evolution of the optical self-energy in the normal and superconducting states.