Charge density wave (CDW) correlations are prevalent in all copper-oxide superconductors. While CDWs in conventional metals are driven by coupling between lattice vibrations and electrons, the role of the electron-phonon coupling (EPC) in cuprate CDWs is strongly debated. Using Cu L3 edge resonant inelastic x-ray scattering (RIXS), we study the CDW and Cu-O bond-stretching phonons in the stripe-ordered cuprate La1.8−xEu0.2SrxCuO4+δ. We investigate the interplay between charge order and EPC as a function of doping and temperature, and find that the EPC is enhanced in a narrow momentum region around the CDW wave vector. By detuning the incident photon energy from the absorption resonance, we extract an EPC matrix element at the CDW wave vector of M≃ 0.36 eV, which decreases to M≃ 0.30 eV at high temperature in the absence of the CDW. Our results suggest a feedback mechanism in which the CDW enhances the EPC which, in turn, further stabilizes the CDW.
@article{arxiv.1910.05526,
title = {Enhanced electron-phonon coupling for charge-density-wave formation in La$_{1.8-x}$Eu$_{0.2}$Sr$_{x}$CuO$_{4+\delta}$},
author = {Y. Y. Peng and A. A. Husain and M. Mitrano and S. Sun and T. A. Johnson and A. V. Zakrzewski and G. J. MacDougall and A. Barbour and I. Jarrige and V. Bisogni and P. Abbamonte},
journal= {arXiv preprint arXiv:1910.05526},
year = {2020}
}