Agustin Schiffrin
Two-dimensional (2D) and layered materials with a kagome crystal structure – where atoms or molecules are arranged in corner-sharing equilateral triangles – host both Dirac and flat electronic bands, offering a rich space to realise tuneable topological and strongly correlated electronic phases. Strong electron-electron correlations have been observed recently in inorganic kagome crystals. Although predicted theoretically, such phenomena have not been observed directly in organic systems. The latter offer versatile protocols for bottom-up synthesis via molecular self-assembly and metal-ligand coordination.
Here, I will talk about our recent experiments involving 2D metal-organic frameworks (MOFs) with a kagome structure. In particular, I will focus on the 2D kagome MOF composed of di-cyano-anthracene (DCA) molecules coordinated with copper (Cu) atoms on a noble metal surface. Via low-temperature scanning tunnelling spectroscopy, we observed Kondo screening – by conduction electrons of the underlying metal surface – of unpaired magnetic moments localized at Cu and DCA sites, with a Kondo temperature >120 K.
Our observations are consistent with density functional theory calculations (including on-site Coulomb repulsion U) and mean-field Hubbard modelling, which show that these localized magnetic moments are the result of strong interactions between electrons of the 2D kagome MOF. Our work paves the way for atomically precise, meso-scaled 2D MOFs for strongly correlated electronics and spintronics.
About the presenter
CI Dr Agustin Schiffrin is an ARC Future Fellow. He investigates optically driven topological phases of materials by means of state-of-the-art ultrafast photonics, pump-probe spectroscopy and time-resolved scanning probe microscopy techniques. He is mainly involved in Research Theme 1 and Research Theme 3.