Observation of termination-dependent topological connectivity in a magnetic Weyl kagome-lattice

TL;DR

This study demonstrates how different surface terminations in the magnetic Weyl kagome-lattice Co$_3$Sn$_2$S$_2$ influence the topological connectivity of Weyl points, linking surface electronic environments to bulk topological features.

Contribution

It provides direct experimental evidence of termination-dependent topological connectivity in a magnetic Weyl kagome system using combined micro-ARPES and first-principles calculations.

Findings

Weyl points connect differently depending on surface termination.

Surface electronic environment affects topological features.

Methodology enables control of topological properties via surface potentials.

Abstract

Engineering surfaces and interfaces of materials promises great potential in the field of heterostructures and quantum matter designer, with the opportunity of driving new many-body phases that are absent in the bulk compounds. Here, we focus on the magnetic Weyl kagome system Co$_3$Sn$_2$S$_2$ and show how for different sample's terminations the Weyl-points connect also differently, still preserving the bulk-boundary correspondence. Scanning-tunnelling microscopy has suggested such a scenario indirectly. Here, we demonstrate this directly for the fermiology of Co$_3$Sn$_2$S$_2$, by linking it to the system real space surfaces distribution. By a combination of micro-ARPES and first-principles calculations, we measure the energy-momentum spectra and the Fermi surfaces of Co$_3$Sn$_2$S$_2$ for different surface terminations and show the existence of topological features directly depending on the top-layer electronic environment. Our work helps to define a route to control bulk-derived topological properties by means of surface electrostatic potentials, creating a realistic and reliable methodology to use Weyl kagome metals in responsive magnetic spintronics.