Charge excitations associated with charge stripe order in the 214-type nickelate and superconducting cuprate

TL;DR

This study investigates charge excitations linked to stripe order in nickelate and cuprate compounds using resonant inelastic x-ray scattering, revealing collective stripe excitations at 1 eV energy transfer.

Contribution

It provides new insights into charge excitations associated with stripe order in 214-type nickelates and cuprates, identifying a possible collective mode or charge excitonic state.

Findings

Charge excitations observed at 1 eV energy transfer.

Excitations correspond to stripe spatial periods.

Possible interpretation as collective stripe mode or charge excitonic state.

Abstract

Charge excitations were studied for stipe-ordered 214 compounds, La$_{5/3}$Sr$_{1/3}$NiO$_{4}$ and 1/8-doped La$_{2}$(Ba, Sr)$_{x}$CuO$_{4}$ using resonant inelastic x-ray scattering in hard x-ray regime. We have observed charge excitations at the energy transfer of 1 eV with the momentum transfer corresponding to the charge stripe spatial period both for the diagonal (nikelate) and parallel (cuprates) stripes. These new excitations can be interpreted as a collective stripe excitation or charge excitonic mode to a stripe-related in-gap state.