  Two-dimensional (2D) metal-organic frameworks (MOFs) in a kagome lattice can
exhibit strong electron-electron interactions, which can lead to tunable
quantum phases including many exotic magnetic phases. While technological
developments of 2D MOFs typically take advantage of substrates for growth,
support, and electrical contacts, investigations often ignore substrates and
their dramatic influence on electronic properties of MOFs. Here, we show how
substrates alter the correlated magnetic phases in kagome MOFs using systematic
density functional theory and mean-field Hubbard calculations. We demonstrate
that MOF-substrate coupling, MOF-substrate charge transfer, strain, and
external electric fields are key variables, activating and deactivating
magnetic phases in these materials. While we consider the example of
kagome-arranged 9,10-dicyanoanthracene molecules coordinated with copper atoms,
our findings should generalise to any kagome lattice. This work offers useful
predictions for tunable interaction-induced magnetism in surface-supported 2D
organic materials, opening the door to solid-state electronic and spintronic
technologies based on such systems.
