Realization of a Two-Dimensional Lieb Lattice in a Metal-Inorganic Framework with Flat Bands and Topological Edge States

TL;DR

This paper reports the successful synthesis and characterization of a two-dimensional platinum-phosphorus Lieb lattice on a gold substrate, revealing flat bands and topological edge states with potential for novel electronic phases.

Contribution

It demonstrates the first experimental realization of a 2D Lieb lattice in a metal-inorganic framework, overcoming structural instability through computational design and molecular beam epitaxy.

Findings

Verification of Lieb lattice morphology via STM

Observation of electronic flat bands

Prediction of topological Dirac edge states

Abstract

Flat bands and Dirac cones in materials are at the source of the exotic electronic and topological properties. The Lieb lattice is expected to host these electronic structures, arising from quantum destructive interference. Nevertheless, the experimental realization of a two-dimensional Lieb lattice remained challenging to date due to its intrinsic structural instability. After computationally designing a Platinum-Phosphorus (Pt-P) Lieb lattice, we have successfully overcome its structural instability and synthesized it on a gold substrate via molecular beam epitaxy. Low-temperature scanning tunneling microscopy and spectroscopy verified the Lieb lattice's morphology and electronic flat bands. Furthermore, topological Dirac edge states stemming from pronounced spin-orbit coupling induced by heavy Pt atoms have been predicted. These findings convincingly open perspectives for creating metal-inorganic framework-based atomic lattices, offering prospects for strongly correlated phases interplayed with topology.