Magnetic Real Chern Insulator in 2D Metal–Organic Frameworks

Abstract

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 2z 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.

Hidden Real Topology and Unusual Magnetoelectric Responses in Two‐Dimensional Antiferromagnets

“…This means that the ML‐CrSeO is also the first material example of a 2D AFM RCI. Compared with the previously reported nonmagnetic and ferromagnetic RCIs, [ 5,9–13 ] the topological corner states in ML‐CrSeO are spin‐polarized, however, the direction of the spin polarization is corner dependent, leading to a unique SCC effect in 2D AFM RCIs. The SCC can be directly observed by spin‐resolved scanning tunneling spectroscopy (STS).…”

“…Various real topological phases are proposed in nonmagnetic systems without SOC, including 2D and 3D RCIs, Z 2 nodal lines, Z 2 nodal surfaces, real Weyl and Dirac points, [ 2,5–18 ] and some of them have been experimentally realized. [ 14–16 ] The 2D magnetic materials can also host the real topology, [ 2 ] and have many important properties and possible applications that cannot be found in nonmagnetic systems.…”

“…[ 19 ] Recently, Zhang et al. [ 13 ] demonstrated that the 2D RCI could appear in ferromagnetic systems regardless of the SOC strength. However, the 2D RCI with AFM order has never been studied.…”

“…This formula () successfully predicts many RCIs and topological Z 2 nodal line materials. [ 5–16 ] Notably, 2D RCIs are associated with the topological corner states. [ 1–3 ] This characteristic exhibits a notable divergence from trivial atomic insulators, hence, providing distinct indications for experimental identification.…”

Mechanical Control of Quantum Transport in Graphene

“…qubits, [1][2][3] spintronics, [4][5][6][7] and valleytronics) [8][9][10][11] and manybody quantum phases (e.g. superconductivity, [12][13][14][15] topological transitions, [13,[16][17][18][19][20] and magnetic transitions). [21][22][23] For example, even a simple uniform uniaxial-strain could create high on-off ratio graphene transistors without needing a bandgap, [24,25] act as topological switch turning a trivial insulator into a quantum spin Hall system, [7] or tune the superconducting phase diagram DOI: 10.1002/adma.202313629 of magic-angle bilayer graphene.…”