SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 23: Kagome Systems

TT 23.4: Vortrag

Dienstag, 28. März 2023, 10:15–10:30, HSZ 304

Indication of a strong coupling charge density wave in CsV₃Sb₅ — •Leander Peis^1,2,3, Ge He^1,4, and Rudolf Hackl^1,2,3 — ¹Walther Meissner Institut, Bayerische Akademie der Wissenschaften, Garching 85748, Germany — ²Technische Universität München, Garching 85748, Germany — ³IFW Dresden, Dresden 01062, Germany — ⁴University College Cork, Cork, Ireland

A prominent example for studying the interplay of electronic correlations and non-trivial topology is the material class of AV₃Sb₅ (A=K,Rb,Cs), displaying unconventional charge order in the range of 100 K and superconductivity at temperatures below 2.5 K. Here, we present a polarization-dependent Raman scattering study of the Kagome metal CsV₃Sb₅, focusing on the charge density wave (CDW). We resolve several signatures of strong-coupling between the lattice and the electronic system. First, the energy of the A_1g Γ-point phonon exhibits a discontinuity at the phase transition temperature T_CDW = 95 K. Second, the magnitude and symmetry dependence of the observed CDW energy gap 2Δ suggest strong coupling and a substantial anisotropy. Third, the observed A_1g amplitude mode depends weaker on temperature than expected and displays an asymmetric Fano-type line shape, particularly around 70 K. We interpret this deviation in terms of strong coupling between the phonon-like amplitude mode and the electronic continuum. To the best of our knowledge such an asymmetry of an amplitude mode has not been observed before.