Imaging real-space flat band localization in kagome magnet FeSn

Direct imaging and tuning of flat band localization in kagome materials remains a challenge. Here, scanning tunneling microscopy and photoemission spectroscopy are used to study FeSn, revealing real-space localization and magnetic tuning of the flat band state within the Fe3Sn kagome lattice layer. Kagome lattices host flat bands due to their frustrated lattice geometry, which leads to destructive quantum interference of electron wave functions. Here, we report imaging of the kagome flat band localization in real-space using scanning tunneling microscopy. We identify both the Fe3Sn kagome lattice layer and the Sn-2 honeycomb layer with atomic resolution in kagome antiferromagnet FeSn. On the Fe3Sn lattice, at the flat band energy determined by the angle resolved photoemission spectroscopy, tunneling spectroscopy detects an unusual state localized uniquely at the Fe kagome lattice network. We further show that the vectorial in-plane magnetic field manipulates the spatial anisotropy of the localization state within each kagome unit cell. Our results are consistent with the real-space flat band localization in the magnetic kagome lattice. We further discuss the magnetic tuning of flat band localization under the spin-orbit coupled magnetic kagome lattice model.

Automated summary

Direct imaging and magnetic tuning of flat band localization in kagome materials is achieved through scanning tunneling microscopy and photoemission spectroscopy. This study provides crucial insights into the localization of flat band states.