Abstract

Kagome materials with corner-shared triangular sublattices are fascinating because of their unique crystal and electronic structures. In this talk, I will first introduce the charge density wave (CDW) orders in the intriguing kagome metals AV3 Sb5 (A = K, Rb, Cs), where the van Hove singularity-related Fermi surface nesting mechanism is believed to be critical for the formation of CDW . I will further show that our recent experiment demonstrates that the phonon softening and electron-phonon coupling mechanism is also essential. Then, I will introduce different CDW orders in a newly discovered kagome metal ScV6Sn6, and propose a ground-state CDW , which, different from the initial observation, is approved immediately by experiments. Unlike CDWs in AV3 Sb5, CDWs in ScV6Sn6 are induced purely by the phonon softening mechanism despite the appearance of two van Hove singularities close to the Fermi level. I will summarize the similarities and differences between these two types of kagome metals. Finally, if time permits, I will show our most recent predictions on the unexpected surface charge orders in kagome series RX6 Sn6 (R=rare earth elements, X = V, Mn) due to the surface phonon-spin interaction.