Discovery of charge order and corresponding edge state in kagome magnet FeGe

TL;DR

This study reveals a 2x2 charge order and a robust edge state in the magnetic kagome lattice of FeGe, linking charge order with antiferromagnetism and topological features, advancing understanding of quantum phases in kagome materials.

Contribution

It uncovers the charge order and edge states in FeGe's kagome lattice through spectroscopic imaging, revealing their magnetic and topological properties.

Findings

Identified a 2x2 charge order in FeGe kagome lattice.

Discovered a robust edge state within the charge order gap.

Demonstrated the link between antiferromagnetism and charge order anisotropy.

Abstract

Kagome materials often host exotic quantum phases, including spin liquids, Chern gap, charge order, and superconductivity. Existing scanning microscopy studies of the kagome charge order have been limited to non-kagome surface layers. Here we tunnel into the kagome lattice of FeGe to uncover features of the charge order. Our spectroscopic imaging identifes a 2x2 charge order in the magnetic kagome lattice, resembling that discovered in kagome superconductors. Spin-mapping across steps of unit-cell-height demonstrates that this charge order emerges from spin-polarized electrons with an antiferromagnetic stacking order. We further uncover the correlation between antiferromagnetism and charge order anisotropy, highlighting the unusual magnetic coupling of the charge order. Finally, we detect a pronounced edge state within the charge order energy gap, which is robust against the irregular shape of the kagome lattice edges. We discuss our results with the theoretically considered topological features of the kagome charge order including orbital magnetism and bulk-boundary correspondence.