Atomic perspective on the topological magnetism in kagome metal Co3Sn2S2

TL;DR

This paper reviews recent advances in using scanning tunneling microscopy to study the topological and magnetic properties of kagome metal Co3Sn2S2, highlighting methodologies, findings, and challenges in understanding its complex electronic states.

Contribution

It provides a systematic overview of STM-based techniques and insights into the topological magnetism of Co3Sn2S2, emphasizing surface identification, Berry curvature effects, and boundary states.

Findings

Identification of surface states using chemical markers

Observation of Berry curvature induced flat band magnetism

Analysis of Weyl boundary states and Fermi arc detection challenges

Abstract

Topological quantum materials with kagome lattices have attracted intense interest due to their unconventional electronic structures, which exhibit nontrivial topology, anomalous magnetism, and electronic correlations. Among these, Co3Sn2S2 stands out as a prototypical kagome metal, uniquely combining intrinsic ferromagnetism with topologically nontrivial electronic states. This perspective presents a systematic overview of recent advances in studying kagome metal Co3Sn2S2 achieved through scanning tunneling microscopy. We begin by introducing different methodologies for surface identification and propose using designer layer-selective chemical markers for conclusive surface identification. We then discuss the Berry curvature induced flat band orbital magnetism and the associated unconventional Zeeman effect. Furthermore, we explore boundary states arising from Weyl topology and analyze challenges in detecting Fermi arcs via quasiparticle interference patterns and in uncovering the topological aspect of the edge states. Finally, we review recent observations of spin-orbit-coupled quantum impurity states through spin-polarized tunneling spectroscopy, as well as their connection to Weyl topology and flat band magnetism. We also provide in-depth analysis and constructive comments on the limitations of the current research approach. This review highlights the critical role of scanning tunneling microscopy in unraveling the intricate interplay between topology, magnetism, and correlations at the atomic scale, and the methodology discussed here can be applied to study other topological quantum materials in general.