Chern insulators realized in two-dimensional metal organic framework kagome lattice

Magnetic topological insulators have attracted a lot of attention for the possible quantum anomalous Hall effect (QAHE), even without external magnetic fields. However, their realization is still limited to extremely low temperatures due to the limited bulk energy gap and ferromagnetic ordering temperatures. As a way to searching for high-temperature QAHE materials, we investigate candidate systems of high-temperature Chern insulators. Here, we report that the transition-metal bis-dithiolene, M$_3$​C$_{12}$​S$_{12}$​​​ (M = Mn and Fe), metal organic framework (MOF) kagome lattice can be a two-dimensional (2D) ferromagnetic insulator with nontrivial Chern number. On-site Coulomb interactions play a crucial role in bringing a nontrivial topological band with a nonzero Chern number. We show sulfur and carbon-based ligands play a vital role in making the complexes topologically nontrivial. The high magnetic Curie temperatures, estimated from density-functional-theory total energy calculations and Monte Carlo simulations, are 234 K for Mn and 281 K for Fe systems. Together with a bandgap as large as 22 meV, these 2D MOF kagome lattices can be robust 2D ferromagnetic organic Chern insulators. We also provide a general picture for understanding the magnetic properties of MOF in a two-dimensional kagome lattice through extensive first-principles calculations on various metals and ligands.