Topological surface Fermi arcs in the magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$

TL;DR

This paper theoretically investigates the topological surface Fermi arcs in the magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$, predicting observable surface states and providing insights for experimental ARPES and STM studies.

Contribution

It offers a detailed theoretical analysis of surface Fermi arcs in Co$_3$Sn$_2$S$_2$ and Co$_3$Sn$_2$Se$_2$, including surface termination effects and implications for experimental detection.

Findings

Fermi arc states range from Weyl point energy to E_F - 0.1 eV on Sn-terminated surface

Surface states are observable via ARPES measurements

Calculated joint density of states supports STM quasiparticle interference analysis

Abstract

Very recently, the half-metallic compound Co$_3$Sn$_2$S$_2$ was predicted to be a magnetic WSM with Weyl points only 60 meV above the Fermi level ($E_F$). Owing to the low charge carrier density and large Berry curvature induced,Co$_3$Sn$_2$S$_2$ possesses both a large anomalous Hall conductivity (AHC) and a large anomalous Hall angle (AHA), which provide strong evidence for the existence of Weyl points in Co$_3$Sn$_2$S$_2$. In this work, we theoretically studied the surface topological feature of Co$_3$Sn$_2$S$_2$ and its counterpart Co$_3$Sn$_2$Se$_2$. By cleaving the sample at the weak Sn--S/Se bonds, one can achieve two different surfaces terminated with Sn and S/Se atoms, respectively. The resulting Fermi arc related states can range from the energy of the Weyl points to $E_F$--0.1 eV in the Sn-terminated surface. Therefore, it should be possible to observe the Fermi arcs in angle-resolved photoemission spectroscopy (ARPES) measurements. Furthermore, in order to simulate quasiparticle interference (QPI) in scanning tunneling microscopy (STM) measurements, we also calculated the joint density of states (JDOS) for both terminals. This work would be helpful for a comprehensive understanding of the topological properties of these two magnetic WSMs and further ARPES and STM measurements.