Magnetic Real Chern Insulator in 2D Metal-Organic Frameworks.

Real Chern insulators have attracted great interest, but so far, their material realization is limited to nonmagnetic crystals and systems without spin-orbit coupling. Here, we reveal the magnetic real Chern insulator (MRCI) state in a recently synthesized metal-organic framework material Co 3 (HITP) 2 . Its ground state with in-plane ferromagnetic ordering hosts a nontrivial real Chern number, enabled by the C 2 z T symmetry and robustness against spin-orbit coupling. Distinct from previous nonmagnetic examples, the topological corner zero modes of MRCIs are spin-polarized. Furthermore, under small tensile strains, the material undergoes a topological phase transition from the MRCI to a magnetic double-Weyl semimetal phase, via a pseudospin-1 critical state. Similar physics can also be found in closely related materials Mn 3 (HITP) 2 and Fe 3 (HITP) 2 , which also exist. Possible experimental detections and implications of an emerging magnetic flat band in the system are discussed.