Charge-transfer exciton in La2CuO4 probed with resonant inelastic x-ray scattering

TL;DR

This study uses high-resolution resonant inelastic x-ray scattering to investigate charge-transfer excitations in La2CuO4, revealing detailed spectral features, their momentum and temperature dependence, and coupling effects with lattice motion.

Contribution

It provides new high-resolution spectral data and detailed analysis of charge-transfer excitations and their dispersion in La2CuO4, highlighting lattice-electron coupling effects.

Findings

Identification of spectral features not seen in earlier data

Measurement of momentum dependence and dispersion of excitations

Observation of a dispersionless d-d crystal field excitation at 1.8 eV

Abstract

We report a high-resolution resonant inelastic x-ray scattering study of La2CuO4. A number of spectral features are identified that were not clearly visible in earlier lower-resolution data. The momentum dependence of the spectral weight and the dispersion of the lowest energy excitation across the insulating gap have been measured in detail. The temperature dependence of the spectral features was also examined. The observed charge transfer edge shift, along with the low dispersion of the first charge transfer excitation are attributed to the lattice motion being coupled to the electronic system. In addition, we observe a dispersionless feature at 1.8 eV, which is associated with a d-d crystal field excitation.