Realization of a two-dimensional checkerboard lattice in monolayer Cu$_2$N

TL;DR

This study reports the theoretical prediction and experimental realization of a two-dimensional checkerboard lattice in monolayer Cu$_2$N, demonstrating its stability and electronic properties relevant for future device applications.

Contribution

It is the first to synthesize and characterize a 2D checkerboard lattice in monolayer Cu$_2$N, bridging theoretical models with experimental material realization.

Findings

Monolayer Cu$_2$N$ hosts checkerboard-derived hole pockets near the Fermi level.

The material is stable in air and organic solvents.

Experimental and theoretical analyses confirm the lattice structure and electronic properties.

Abstract

Two-dimensional checkerboard lattice, the simplest line-graph lattice, has been intensively studied as a toy model, while material design and synthesis remain elusive. Here, we report theoretical prediction and experimental realization of the checkerboard lattice in monolayer Cu$_2$N. Experimentally, monolayer Cu$_2$N can be realized in the well-known N/Cu(100) and N/Cu(111) systems that were previously mistakenly believed to be insulators. Combined angle-resolved photoemission spectroscopy measurements, first-principles calculations, and tight-binding analysis show that both systems host checkerboard-derived hole pockets near the Fermi level. In addition, monolayer Cu$_2$N has outstanding stability in air and organic solvents, which is crucial for further device applications.