Mesoscale variations of chemical and electronic landscape on the surface of Weyl semimetal Co$_3$Sn$_2$S$_2$ visualized by ARPES and XPS

TL;DR

This study investigates the complex surface chemistry and electronic structure of the magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$, revealing how surface heterogeneity and disorder influence topological surface states through combined spectromicroscopy and first-principles calculations.

Contribution

It introduces a detailed analysis of surface heterogeneity and disorder in Co$_3$Sn$_2$S$_2$, providing heuristics for identifying variable surface disorder via photoemission techniques.

Findings

Identification of an intermediate disordered surface region.

Correlation of spectral features with surface tin vacancies.

Establishment of heuristics for surface disorder detection.

Abstract

The multiple crystalline terminations in magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$ display distinct topological and trivial surface states, which have successfully been distinguished experimentally. However, a model of pure terminations is known to be inadequate because these surfaces exhibit a high degree of spatial heterogeneity and point disorder. Here we perform a spectromicroscopy study of the surface chemistry and surface electronic structure using photoemission measurements in combination with first-principles calculations of core levels. We identify an intermediate region with properties distinct from both the sulfur and tin terminations, and demonstrate that the spectral features in this region can be associated with a disordered termination with a varying density of surface tin vacancies. This work establishes heuristics for identifying variable surface disorder using photoemission, an important prerequisite to experimentally establishing the behavior of momentum-space topological surface features subject to variable surface disorder on a single cleave.