# Experimental Determination of Momentum-Resolved Electron-Phonon Coupling

## TL;DR

This paper introduces a new experimental approach using RIXS to measure how electrons interact with phonons across different momenta, revealing detailed coupling patterns in quantum materials.

## Contribution

It presents a novel method to quantitatively determine momentum-resolved electron-phonon coupling from RIXS spectra, applicable to various absorption resonances.

## Key findings

- Electron-phonon coupling strongest at the Brillouin zone boundary (~0.17 eV).
- Method validated on NdBa₂Cu₃O₆, consistent with previous studies.
- Applicable to a wide range of quantum materials.

## Abstract

We provide a novel experimental method to quantitatively estimate the electron-phonon coupling and its momentum dependence from resonant inelastic x-ray scattering (RIXS) spectra based on the detuning of the incident photon energy away from an absorption resonance. We apply it to the cuprate parent compound NdBa$_2$Cu$_3$O$_6$ and find that the electronic coupling to the oxygen half-breathing phonon mode is strongest at the Brillouin zone boundary, where it amounts to $\sim 0.17$ eV, in agreement with previous studies. In principle, this method is applicable to any absorption resonance suitable for RIXS measurements and will help to define the contribution of lattice vibrations to the peculiar properties of quantum materials.