Tunable Flat Band in Large‐Scale Kagome Lattice of Single Layer (BETS)₂GaCl₄

Abstract

Kagome lattice is expected to be a perfect platform for hosting exotic emergent phenomena such as negative magnetism and unconventional superconductivity. However, the preparation of such a lattice on a scale of 100 nm or more, with a perfect crystalline order, especially in organic systems, is challenging. Herein, a facile method is presented to fabricate a large scale of epitaxial single‐layer organic Kagome lattice based on (BETS)2GaCl4 on Ag(111) (where BETS is bis(ethylenedithio)tetraselenafulvalene). The lattice accommodates guest molecules with size up to 1 nm, thus making it possible to host a variety of single molecular magnets. This possibility is demonstrated by the in situ selective encapsulation of GaCl4 radicals in the pores. Scanning tunneling microscopy and spectroscopy reveal that both the radical states and the trimer units exhibit sharp and spatially localized peaks at 1.08 and 1.42 eV, respectively. The persistence of these sharp features together with spatial localization, regardless of biasing conditions, suggests an evidence of a frustrated flat band with a possible tuning to incorporate topological order.