Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The coexistence of the charge-density wave (CDW) and the superconducting phase and their tunability under external pressure remains one of the key focus points in understanding the electronic structure of AV3Sb5 (A = K, Rb, Cs) kagome metals. Here, we employ synchrotron-based infrared spectroscopy assisted by density-functional calculations to study the pressure evolution of the electronic structure at room temperature up to 17 GPa experimentally for the first time. The optical spectrum of CsV₃Sb₅ is characterized by the presence of localized carriers seen as a broad peak at finite frequencies in addition to the conventional metallic Drude response. The pressure dependence of this low-energy peak mirrors the re-entrant behavior of superconductivity and may be interpreted in terms of electron-phonon coupling changing with the growth and shrinkage of the Fermi surface (FS). Moreover, drastic modifications in the low-energy interband absorptions are observed upon the suppression of CDW. These changes are related to the upward shift of the Sb2 px +py band that eliminates part of the FS around the M-point, whereas band saddle points do not change significantly. These observations
shed new light on the mixed electronic and lattice origin of the CDW in CsV₃Sb₅.