A Charge-Density-Wave Instability in BaBi
                    
                      1-
                      x
                    
                    Pb
                    
                      x
                    
                    O
                    3
                    Caused by Strong Electron-Phonon Coupling

Abstract(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which are recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays an important role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study interesting excitations in Luttinger liquid materials.

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Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

Nature Communications ◽

10.1038/s41467-021-27946-6 ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Hailan Luo ◽

Qiang Gao ◽

Hongxiong Liu ◽

Yuhao Gu ◽

Dingsong Wu ◽

...

Keyword(s):

Electronic Structure ◽

Fermi Surface ◽

Charge Density ◽

Charge Density Wave ◽

Density Wave ◽

Phonon Coupling ◽

Electronic Nature ◽

Electron Phonon Coupling ◽

Gap Opening ◽

Fermi Surface Reconstruction

AbstractThe Kagome superconductors AV3Sb5 (A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and superconductivity. Unconventional charge density wave (CDW) has been detected in AV3Sb5. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV3Sb5. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV3Sb5. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV3Sb5 superconductors.

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