Scanning tunneling microscopy study of charge density wave kagome metal ScV₆Sn₆

Kagome lattices have received significant attention due to their potential to concurrently exhibit multiple novel quantum phenomena such as flat bands, topologically protected bands, and van Hove singularities related to charge density Waves (CDW). ScV₆Sn₆ is a new kagome metal which displays an unusual CDW pattern in its low-temperature phase below 92K. Its unit cell includes a pair of mirror-related V-Sn kagome layers separated by a honeycomb lattice of Sn. We investigate both the high-temperature and low-temperature phases of ScV₆Sn₆ using scanning tunneling microscopy/spectroscopy (STM/S). Topographic images and dI/dV maps of cleaved samples show two different surface terminations with distinct density of states near the Fermi level. A direct comparison of atomic resolution STM/S measurements and density functional theory simulations attribute these two terminations to the honeycomb Sn and kagome layers. The charge density of the Sn-terminated surface decays more slowly into the vacuum than that of the kagome-terminated surface. The significant difference in the decay lengths must be considered while characterizing the electronic structures of ScV₆Sn₆ with STM and other surface-sensitive methods.