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.

众所周知，当平带与色散带有间隙时，由于库仑相互作用增强，孤立的平带具有各种强相关相位。实现孤立平带的一种方法是打破利布晶格中的现场能量对称性。在这项研究中，我们展示了这种利布晶格的设计。方形大环分子在Ag(111)表面上自组装形成二维超分子晶体，由三种不同尺寸的纳米孔排列成Lieb晶格。被这些纳米孔限制的 Ag(111) 基底的表面态电子表现为具有特定能量的量子点，具体能量取决于孔径。利用扫描隧道光谱和平面波量子模拟，我们揭示了这种人造利布晶格表现出与最近能带相差 0.16 eV 的隔离平坦带隙。该超分子晶体几乎没有缺陷，尺寸可延伸至亚微米，使其成为探索孤立平带奇异特性的实用平台。