Isolated flat band in artificially designed Lieb lattice based on macrocycle supramolecular crystal

• Published in: Communications materials 2024-04, Vol.5 (1), p.54-6, Article 54
• Main Authors: Chen, Cheng-Yi, Li, En, Xie, Huilin, Zhang, Jianyu, Lam, Jacky Wing Yip, Tang, Ben Zhong, Lin, Nian
• Format: Article
• Language: English
• Subjects: 639/301/357/1018; 639/638/541/966; 639/766/119/995; Chemistry and Materials Science; Crystal defects; Crystal lattices; Materials Science; Plane waves; Pore size; Quantum dots; Self-assembly; Silver; Substrates
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-024-00501-8

Isolated flat bands are known to host various strongly correlated phases due to the enhanced Coulomb interactions when the flat bands are gapped from dispersive bands. One way to achieve an isolated flat band is by breaking the on-site energy symmetry in a Lieb lattice. In this study, we demonstrate the design of such a Lieb lattice. The self-assembly of square-shaped macrocycle molecules on a Ag(111) surface forms a two-dimensional supramolecular crystal, comprising three types of nanopores with different sizes arranged in a Lieb lattice. The surface-state electrons of the Ag(111) substrate confined by these nanopores behave as quantum dots with specific energies depending on the pore size. Using scanning tunneling spectroscopy and plane-wave quantum simulation, we reveal that this artificial Lieb lattice exhibits an isolated flat band gapped at 0.16 eV from the nearest band. The supramolecular crystal is nearly defect-free and extends to sub-micrometer size, making it a practical platform for exploring the exotic properties of the isolated flat band. Isolated flat bands can host strongly correlated electronic phases due to the enhancement of the Coulomb interaction. Here, an isolated flat band is realized and visualized in a 2D supramolecular crystal based on self-assembled square-shaped macrocycle molecules on Ag(111) surface arranged in a Lieb lattice.