Magnetic Real Chern Insulator in 2D Metal-Organic Frameworks

Abstract

RealChern 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 magneticreal Chern insulator (MRCI) state in a recently synthesized metal-organicframework material Co-3(HITP)(2). Its ground statewith in-plane ferromagnetic ordering hosts a nontrivial real Chernnumber, enabled by the C (2z ) T symmetry and robustness against spin-orbitcoupling. Distinct from previous nonmagnetic examples, the topologicalcorner zero modes of MRCIs are spin-polarized. Furthermore, undersmall tensile strains, the material undergoes a topological phasetransition from the MRCI to a magnetic double-Weyl semimetal phase,via a pseudospin-1 critical state. Similar physics can also be foundin closely related materials Mn-3(HITP)(2) andFe(3)(HITP)(2), which also exist. Possible experimentaldetections and implications of an emerging magnetic flat band in thesystem are discussed.