Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5
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Abstract
<jats:title>Abstract</jats:title> <jats:p> The Kagome superconductors AV <jats:sub>3</jats:sub> Sb <jats:sub>5</jats:sub> (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 AV <jats:sub>3</jats:sub> Sb <jats:sub>5</jats:sub> . 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 KV <jats:sub>3</jats:sub> Sb <jats:sub>5</jats:sub> . 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 KV <jats:sub>3</jats:sub> Sb <jats:sub>5</jats:sub> . These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV <jats:sub>3</jats:sub> Sb <jats:sub>5</jats:sub> superconductors. </jats:p>