Momentum-resolved charge excitations in high-Tc cuprates studied by resonant inelastic x-ray scattering

TL;DR

This study uses resonant inelastic x-ray scattering to analyze momentum-resolved charge excitations in high-Tc cuprates, revealing how doping affects the dispersion and nature of Mott gap excitations.

Contribution

It provides detailed momentum-resolved insights into charge excitations across different doping levels in high-Tc cuprates using RIXS.

Findings

Mott gap excitation shows larger dispersion along [pi,pi] than [pi,0] in undoped insulators.

Doping weakens the dispersion of Mott gap excitation and introduces intraband excitations.

Electron doping results in prominent Mott gap excitation at zone center and dispersive intraband excitations.

Abstract

We report a Cu K-edge resonant inelastic x-ray scattering (RIXS) study of high-Tc cuprates. Momentum-resolved charge excitations in the CuO2 plane are examined from parent Mott insulators to carrier-doped superconductors. The Mott gap excitation in undoped insulators is found to commonly show a larger dispersion along the [pi,pi] direction than the [pi,0] direction. On the other hand, the resonance condition displays material dependence. Upon hole doping, the dispersion of the Mott gap excitation becomes weaker and an intraband excitation appears as a continuum intensity below the gap at the same time. In the case of electron doping, the Mott gap excitation is prominent at the zone center and a dispersive intraband excitation is observed at finite momentum transfer.