Local gate control of Mott metal-insulator transition in a 2D metal-organic framework

Benjamin Lowe; Bernard Field; Jack Hellerstedt; Julian Ceddia; Henry L. Nourse; Ben J. Powell; Nikhil V. Medhekar; Agustin Schiffrin

doi:10.1038/s41467-024-47766-8

arXiv · 2305.14983

Local gate control of Mott metal-insulator transition in a 2D metal-organic framework

Benjamin Lowe·Bernard Field·Jack Hellerstedt·Julian Ceddia·Henry L. Nourse·Ben J. Powell·Nikhil V. Medhekar·Agustin Schiffrin

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Abstract

Electron-electron interactions in materials lead to exotic many-body quantum phenomena including Mott metal-insulator transitions (MITs), magnetism, quantum spin liquids, and superconductivity. These phases depend on electronic band occupation and can be controlled via the chemical potential. Flat bands in two-dimensional (2D) and layered materials with a kagome lattice enhance electronic correlations. Although theoretically predicted, correlated-electron Mott insulating phases in monolayer 2D metal-organic frameworks (MOFs) with a kagome structure have not yet been realised experimentally. Here, we synthesise a 2D kagome MOF on a 2D insulator. Scanning tunnelling microscopy (STM) and spectroscopy reveal a MOF electronic energy gap of ~200 meV, consistent with dynamical mean field theory predictions of a Mott insulator. Combining template-induced (via work function variations of the substrate) and STM probe-induced gating, we locally tune the electron population of the MOF kagome bands and induce Mott MITs. These findings enable technologies based on electrostatic control of many-body quantum phases in 2D MOFs.

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Benjamin Lowe, Bernard Field, Jack Hellerstedt, Julian Ceddia, Henry L. Nourse, Ben J. Powell, Nikhil V. Medhekar, Agustin Schiffrin. 2023-05-24. Local gate control of Mott metal-insulator transition in a 2D metal-organic framework. https://doi.org/10.1038/s41467-024-47766-8

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