Charge order lock-in by electron-phonon coupling in La1.675Eu0.2Sr0.125CuO4

Qisi Wang; Karin von Arx; Masafumi Horio; Deepak John Mukkattukavil; Julia Küspert; Yasmine Sassa; Thorsten Schmitt; Abhishek Nag; Sunseng Pyon; Tomohiro Takayama; Hidenori Takagi; Mirian Garcia-Fernandez; Ke-Jin Zhou; Johan Chang

doi:10.1126/sciadv.abg7394

Charge order lock-in by electron-phonon coupling in La_1.675Eu_0.2Sr_0.125CuO₄

Sci Adv. 2021 Jun 30;7(27):eabg7394. doi: 10.1126/sciadv.abg7394. Print 2021 Jun.

Authors

Affiliations

¹ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland. qisiwang@physik.uzh.ch johan.chang@physik.uzh.ch.
² Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
³ Department of Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
⁴ Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
⁵ Swiss Light Source, Photon Science Division, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
⁶ Diamond Light Source, Harwell Campus, Didcot, Oxfordshire OX11 0DE, UK.
⁷ Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
⁸ Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
⁹ Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan.

Abstract

Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed to be essential, whereas the role of electron-phonon interaction is unclear. We report an ultrahigh-resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La_1.675Eu_0.2Sr_0.125CuO₄ Phonon softening and lifetime shortening are found around the charge ordering wave vector. In addition to these self-energy effects, the electron-phonon coupling is probed by its proportionality to the RIXS cross section. We find an enhancement of the electron-phonon coupling around the charge-stripe ordering wave vector upon cooling into the low-temperature tetragonal structure phase. These results suggest that, in addition to electronic correlations, electron-phonon coupling contributes substantially to the emergence of long-range charge-stripe order in cuprates.

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