Metallic materials with kagome lattice structure are interesting because their electronic structures can host flat bands, Dirac cones, and van Hove singularities, resulting in strong electron correlations, nontrivial band topology, charge density wave (CDW), and unconventional superconductivity. Recently, kagome lattice compounds AV3Sb5 (A = K, Rb, Cs) are found to have intertwined CDW order and superconductivity. The origin of the CDW has been suggested to be purely electronic, arising from Fermi-surface instabilities of van Hove singularity (saddle point) near the M points. Here we use neutron scattering experiments to demonstrate that the CDW order in CsV3Sb5 is associated with static lattice distortion and a sudden hardening of the B3u longitudinal optical phonon mode, thus establishing that electron-phonon coupling must also play an important role in the CDW order of AV3Sb5.
@article{arxiv.2111.00654,
title = {Electron-phonon coupling in the charge density wave state of CsV$_3$Sb$_5$},
author = {Yaofeng Xie and Yongkai Li and Philippe Bourges and Alexandre Ivanov and Zijin Ye and Jia-Xin Yin and M Zahid Hasan and Aiyun Luo and Yugui Yao and Zhiwei Wang and Gang Xu and Pengcheng Dai},
journal= {arXiv preprint arXiv:2111.00654},
year = {2022}
}