Pressure evolution of electron dynamics in the superconducting kagome metal CsV${}_3$Sb${}_5$

Abstract

The coexistence of the charge-density wave (CDW) and superconducting phases and their tunability under external pressure remains one of the key points in understanding the electronic structure of $A$V${}_3$Sb${}_5$ ($A$ = 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. The optical spectrum of CsV${}_3$Sb${}_5$ 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 reflects the re-entrant behavior of superconductivity and may be interpreted in terms of electron-phonon coupling, varying with the growth and shrinkage of the Fermi surface. 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 $p_x+p_y$ band that eliminates part of the Fermi surface around the $M$-point, whereas band saddle points do not move significantly. These observations shed new light on the mixed electronic and lattice origin of the CDW in CsV${}_3$Sb${}_5$.

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Cited by in corpus (7)

• Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals
• Intriguing Low-Temperature Phase in the Antiferromagnetic Kagome Metal FeGe
• Pressure-dependent Electronic Superlattice in the Kagome-Superconductor CsV${}_3$Sb${}_5$
• Large Fermi surface in pristine kagome metal CsV${}_3$Sb${}_5$ and enhanced quasiparticle effective masses
• Two-dimensional phase diagram of the charge density wave in doped CsV${}_3$Sb${}_5$
• Interplay of $d$- and $p$-states in RbTi${}_3$Bi${}_5$ and CsTi${}_3$Bi${}_5$ flat-band kagome metals
• Beyond kagome: $p$-bands in kagome metals