Ghost states and surface structures of the charge density wave kagome metal ScV 6 Sn 6

Abstract

We investigate the high temperature phase of the kagome metal ScV$_6$Sn$_6$ using scanning tunneling microscopy/spectroscopy (STM/S) and density functional theory (DFT) calculations. STM topographic imagery of the cleaved sample shows two different surface terminations: flat islands of with Sn-termination and trenches terminated by kagome layers with Sn as the outermost atomic layer. STS measurements on Sn-terminated and kagome-terminated surfaces show significant differences, especially with the presence of notable density of states (DOS) near the Fermi level in the former case. We predict that because of the relative localization of charge density on the kagome-terminated surface, it is possible to measure a ``ghost state" where weak tunneling intensity appears away from the atomic sites and can lead to a misattribution of the surface termination. Understanding the surface structure of this versatile quantum material provides essential information for interpreting surface-sensitive experiments, tailoring material properties, engineering interfaces, and controlling stability and reactivity. This knowledge paves the way for further exploration and potential applications of kagome lattice materials in various fields, including quantum computing, topological physics, and advanced electronic devices.