Two-dimensional band structure in honeycomb metal-organic frameworks

TL;DR

This paper reports the successful synthesis and characterization of two-dimensional honeycomb metal-organic frameworks on graphene, revealing their intrinsic electronic band structure and paving the way for designer quantum materials.

Contribution

It demonstrates the synthesis of 2D MOFs on graphene and provides experimental evidence of their intrinsic electronic band structure free from substrate interactions.

Findings

Formation of 2D band structure in MOFs confirmed

Decoupling of MOF electronic properties from substrate

Potential for engineering complex electronic structures

Abstract

Metal-organic frameworks (MOFs) are an important class of materials that present intriguing opportunities in the fields of sensing, gas storage, catalysis, and optoelectronics. Very recently, two-dimensional (2D) MOFs have been proposed as a flexible material platform for realizing exotic quantum phases including topological and anomalous quantum Hall insulators. Experimentally, direct synthesis of 2D MOFs has been essentially confined to metal substrates, where the interaction with the substrate masks the intrinsic electronic properties of the MOF. Here, we demonstrate synthesis of 2D honeycomb metal-organic frameworks on a weakly interacting epitaxial graphene substrate. Using low-temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM) complemented by density-functional theory (DFT) calculations, we show the formation of 2D band structure in the MOF decoupled from the substrate. These results open the experimental path towards MOF-based designer quantum materials with complex, engineered electronic structures.