Order-disorder charge density wave instability in the kagome metal (Cs,Rb)V<sub>3</sub>Sb<sub>5</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36823175.
- Also identified by DOI 10.1038/s41467-023-36668-w and PMC identifier 9950456.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The origin of the charge density wave phases in the kagome metal compound AV<sub>3</sub>Sb<sub>5</sub> is still under great scrutiny. Here, we combine diffuse and inelastic x-ray scattering to identify a 3-dimensional precursor of the charge order at the L point that condenses into a CDW through a first order phase transition. The quasi-elastic critical scattering indicates that the dominant contribution to the diffuse precursor is the elastic central peak without phonon softening. However, the inelastic spectra show a small broadening of the Einstein-type phonon mode on approaching T<sub>CDW</sub>. Our results point to the situation where the Fermi surface instability at the L point is of order-disorder type with critical growth of quasi-static domains. The experimental data indicate that the CDW consists on an alternating Star of David and trihexagonal distortions and its dynamics goes beyond the classical weak-coupling scenario and is discussed within strong-electron phonon coupling and non-adiabatic models.