Transition-metal phthalocyanine monolayers as new Chern insulators

To explore new materials for the realization of the quantum anomalous Hall effect (QAHE), we studied electronic, magnetic and topological properties of transition-metal phthalocyanine (TMPc) monolayers in a square lattice. Many of them have large topologically nontrivial band gaps and integer Chern numbers. In particular, the Fermi level of MoPc lies right in the band gap (Eg=8.1 meV) and has large magnetic anisotropy energy (MAE=2.0 meV per Mo atom) and a Curie temperature of 16 K, showing its usefulness for applications. The presence of topologically protected edge state in a MoPc nanoribbon further confirms it as a new two-dimensional topological insulator. This much widens the search of QAHE materials for the design of quantum devices.