Dynamics and resilience of the unconventional charge density wave in ScV6Sn6 bilayer kagome metal

• Published in: Communications materials 2023-12, Vol.4 (1), p.103-8, Article 103
• Main Authors: Tuniz, Manuel, Consiglio, Armando, Puntel, Denny, Bigi, Chiara, Enzner, Stefan, Pokharel, Ganesh, Orgiani, Pasquale, Bronsch, Wibke, Parmigiani, Fulvio, Polewczyk, Vincent, King, Phil D. C., Wells, Justin W., Zeljkovic, Ilija, Carrara, Pietro, Rossi, Giorgio, Fujii, Jun, Vobornik, Ivana, Wilson, Stephen D., Thomale, Ronny, Wehling, Tim, Sangiovanni, Giorgio, Panaccione, Giancarlo, Cilento, Federico, Di Sante, Domenico, Mazzola, Federico
• Format: Article
• Language: English
• Subjects: 639/766/119; 639/766/119/995; Banded structure; Charge density waves; Chemistry and Materials Science; Couplings; Degrees of freedom; Dynamic structural analysis; Fermi surfaces; First principles; Materials Science; Phonons; Physical properties; Playgrounds; Singularities; Stabilization; Topology
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-023-00430-y

Long-range electronic ordering descending from a metallic parent state constitutes a rich playground to study the interplay of structural and electronic degrees of freedom. In this framework, kagome metals are in the most interesting regime where both phonon and electronically mediated couplings are significant. Several of these systems undergo a charge density wave transition. However, to date, the origin and the main driving force behind this charge order is elusive. Here, we use the kagome metal ScV 6 Sn 6 as a platform to investigate this problem, since it features both a kagome-derived nested Fermi surface and van-Hove singularities near the Fermi level, and a charge-ordered phase that strongly affects its physical properties. By combining time-resolved reflectivity, first principles calculations and photo-emission experiments, we identify the structural degrees of freedom to play a fundamental role in the stabilization of charge order, indicating that ScV 6 Sn 6 features an instance of charge order predominantly originating from phonons. Kagome metals are remarkably interesting due to the strong interplay of topology, magnetism, van-Hove singularities, correlated flat bands, and structural degrees of freedom. Here, the driving mechanism and dynamics of the charge density wave phase in ScV6Sn6 are investigated by experimental and theoretical techniques, revealing a predominant role of phonons in its stabilization.