Self-Intercalated 1T-FeSe₂ as an Effective Kagome Lattice.

Abstract

In kagome lattice, with the emergence of Dirac cones and flat band in electronic structure, it provides a versatile ground for exploring intriguing interplay among frustrated geometry, topology and correlation. However, such engaging interest is strongly limited by available kagome materials in nature. Here we report on a synthetic strategy of constructing kagome systems via self-intercalation of Fe atoms into the van der Waals gap of FeSe₂ via molecular beam epitaxy. Using low-temperature scanning tunneling microscopy, we unveil a kagome-like morphology upon intercalating a 2 × 2 ordered Fe atoms, resulting in a stoichiometry of Fe₅Se₈. Both the bias-dependent STM imaging and theoretical modeling calculations suggest that the kagome pattern mainly originates from slight but important reconstruction of topmost Se atoms, incurred by the nonequivalent subsurface Fe sites due to the intercalation. Our study demonstrates an alternative approach of constructing artificial kagome structures, which envisions to be tuned for exploring correlated quantum states.