講師:Prof. Johan Chang (Physik-Institut, Universität Zürich)
日時:2021年6月16日(水) 17:00~

タイトル:Electron-Phonon-Coupling and Charge Stripe Order in the cuprates

 Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed essential whereas the role of electron-phonon interaction is unclear. In this talk, we report an ultra high resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La1.675 Eu0.2 Sr0.125 CuO4 . 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 significantly to the emergence of long-range charge-stripe order in cuprates [1,2].

[1] Qisi Wang et al., Phys. Rev. Lett. 124, 187002 (2020)
[2] Qisi Wang et al., arXiv:2012.10503 Accepted in Science Advances (2021)