Tunable Topological Dirac Surface States and Van Hove Singularities in Kagome Metal GdV${_6}$Sn${_6}$

TL;DR

This study uncovers tunable topological Dirac surface states and Van Hove singularities in the magnetic kagome metal GdV6Sn6, demonstrating control over electronic states and potential for spintronic applications.

Contribution

It provides the first clear observation of topologically nontrivial Dirac surface states in a magnetic kagome metal and demonstrates their tunability via surface potassium deposition.

Findings

TDSSs originate from Z2 bulk topology

Multiple VHSs identified near Fermi level

Dirac point tunable from above to below Fermi level

Abstract

Transition-metal-based kagome materials at van Hove filling are a rich frontier for the investigation of novel topological electronic states and correlated phenomena. To date, in the idealized two-dimensional kagome lattice, topologically nontrivial Dirac surface states (TDSSs) have not been unambiguously observed, and the manipulation of TDSSs and van Hove singularities (VHSs) remains largely unexplored. Here, we reveal TDSSs originating from a Z${_2}$ bulk topology and identify multiple VHSs near the Fermi level ($\textit{E}$${_F}$) in magnetic kagome material GdV${_6}$Sn${_6}$. Using in-situ surface potassium deposition, we successfully realize manipulation of the TDSSs and VHSs. The Dirac point of the TDSSs can be tuned from above to below ($\textit{E}$${_F}$), which reverses the chirality of the spin texture at the Fermi surface. These results establish GdV${_6}$Sn${_6}$ as a fascinating platform for studying the nontrivial topology, magnetism and correlation effects native to kagome lattices. They also suggest potential application of spintronic devices based on kagome materials.