Perturbations to Flat Bands in Kagome Metal FeSn/STO

Kagome materials are currently under investigation due to their ability to host many phenomena otherwise found over a range of material systems. For example, graphene’s honeycomb lattice features Dirac points (DPs) and van Hove singularities (vHSs) far from the Fermi energy, while flat bands (FBs) emerge and vHSs are brought close to the Fermi energy in twisted graphene structures [1-2]. However, Kagome materials intrinsically host DPs, vHSs, and FBs relatively close to the Fermi energy [3]. We demonstrated epitaxial thin films of FeSn with an alternate stacking of Fe₃Sn Kagome lattice and Sn₂ honeycomb lattice on a strontium titanate (STO) substrate using molecular beam epitaxy (MBE) and characterized the films using scanning tunneling microscopy/spectroscopy (STM/S). Both vertical and lateral heterostructures between the Kagome Fe₃Sn layer and the honeycomb Sn₂ layer were formed in the as grown epitaxial films [4]. Perturbations to the FBs and FBs-induced correlated behaviors were discovered at the boundaries of the heterostructures, which shed light on a new pathway for engineering the electronic properties of the Kagome lattice that can be beneficial for the development of future quantum devices.

[1] K. Kim et al., PNAS 114, 3364-3369 (2017).

[2] G. Li et al., Nat Phys 6, 109 (2010).

[3] Y. Wang et al., Nat Rev Phys 5, 635–658 (2023).

[4] T. A. Pham et al., ACS Nano 18, 8768−8776 (2024).