Coexisting pseudogap, charge transfer gap, and Mott gap energy scales in the resonant inelastic x-ray scattering spectra of electron-doped cuprates

TL;DR

This paper models resonant inelastic x-ray scattering spectra in electron-doped cuprates, revealing the coexistence of pseudogap, charge transfer gap, and Mott gap energy scales, and matches experimental observations.

Contribution

It introduces a comprehensive theoretical approach including bosonic fluctuations to identify multiple energy scales in RIXS spectra of electron-doped cuprates, aligning with experimental data.

Findings

Identification of three key energy scales: pseudogap, charge transfer gap, Mott gap

Reproduction of experimental features like gap collapse and spectral broadening

Agreement with experimental doping-dependent spectral weight transfer

Abstract

We present a computation of Cu K-edge resonant inelastic x-ray scattering (RIXS) spectra for electron-doped cuprates which includes coupling to bosonic fluctuations. Comparison with experiment over a wide range of energy and momentum transfers allows us to identify the signatures of three key normal-state energy scales: the pseudogap, charge transfer gap, and Mott gap. The calculations involve a three band Hubbard Hamiltonian based on Cu $d_{x^2-y^2}$ and O $p_x$, $p_y$ orbitals, with a self-energy correction which arises due to spin and charge fluctuations. Our theory reproduces characteristic features e.g., gap collapse, large spectral weight broadening, and spectral weight transfer as a function of doping, as seen in experiments.