  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.
