Manifestation of strongly correlated electrons in a 2D kagome metal-organic framework

TL;DR

This study demonstrates the emergence of strongly correlated electronic states in a 2D kagome metal-organic framework, revealing Kondo screening and magnetic interactions, thus opening new avenues for organic nanoelectronics and spintronics.

Contribution

It reports the synthesis of a 2D kagome MOF with strong electron correlations, combining experimental spectroscopy and theoretical modeling to reveal magnetic phenomena in organic materials.

Findings

Observation of Kondo screening in the MOF

Emergence of local magnetic moments from strong electron interactions

Potential for organic materials in nanoelectronics and spintronics

Abstract

The kagome lattice, whose electronic valence band (VB) structure includes two Dirac bands and one flat band, offers a rich space to realise tuneable topological and strongly correlated electronic phases in two-dimensional (2D) and layered materials. While strong electron correlations have been observed in inorganic kagome crystals, they remain elusive in organic systems. The latter offer versatile synthesis protocols via molecular self-assembly and metal-ligand coordination. Here, we report the synthesis of a 2D metal-organic framework (MOF) where di-cyano-anthracene (DCA) molecules form a kagome arrangement via coordination with copper (Cu) atoms on a silver surface [Ag(111)]. Low-temperature scanning tunnelling spectroscopy revealed Kondo screening--by the Ag(111) conduction electrons--of magnetic moments localised at Cu and DCA sites of the MOF. Density functional theory and mean-field Hubbard modelling show that these local moments emerge from strong interactions between kagome MOF electrons, enabling organic 2D materials as viable platforms for strongly correlated nanoelectronics and spintronics.