Flat band separation and robust spin-Berry curvature in bilayer kagome metals

Abstract

Kagome materials have emerged as a setting for emergent electronic phenomena that encompass different aspects of symmetry and topology. It is debated whether the XV${}_6$Sn${}_6$ kagome family (where X is a rare earth element), a recently discovered family of bilayer kagome metals, hosts a topologically non-trivial ground state resulting from the opening of spin-orbit coupling gaps. These states would carry a finite spin-Berry curvature, and topological surface states. Here, we investigate the spin and electronic structure of the XV${}_6$Sn${}_6$ kagome family. We obtain evidence for a finite spin-Berry curvature contribution at the center of the Brillouin zone, where the nearly flat band detaches from the dispersing Dirac band because of spin-orbit coupling. In addition, the spin-Berry curvature is further investigated in the charge density wave regime of ScV${}_6$Sn${}_6$, and it is found to be robust against the onset of the temperature-driven ordered phase. Utilizing the sensitivity of angle resolved photoemission spectroscopy to the spin and orbital angular momentum, our work unveils the spin-Berry curvature of topological kagome metals, and helps to define its spectroscopic fingerprint.

21 pages, 4 figures

References in corpus (11)

• Topological Insulators with Inversion Symmetry
• High temperature fractional quantum Hall states
• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Unconventional Fermi surface instabilities in the Kagome Hubbard Model
• Negative flat band magnetism in a spin-orbit coupled correlated kagome magnet
• Theoretical prediction of a strongly correlated Dirac metal
• Realizing Kagome Band Structure in Two-Dimensional Kagome Surface States of $R{V}_{6}S{n}_6$ ($R$=Gd,Ho)
• Topological Thermal Hall Effect in Frustrated Kagomé Antiferromagnets
• Large anomalous Hall effect in the kagome ferromagnet LiMn${}_6$Sn${}_6$
• GdV6Sn6: a Multi-carrier Metal with Non-magnetic 3d-electron Kagome Bands and 4f-electron Magnetism
• Topological phases, topological flat bands, and topological excitations in a one-dimensional dimerized lattice with spin-orbit coupling