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Magnetic two-dimensional (2D) topological insulators with spontaneous magnetization have been predicted to host quantum anomalous Hall effects (QAHEs). For organic topological insulators, the QAHE only exists in honeycomb or Kagome organometallic lattices based on theoretical calculations. Recently, coloring-triangle (CT) lattice has been found to be mathematically equivalent to a Kagome lattice, suggesting a potential 2D lattice to realize QAHE. Here, based on first-principles calculations, we predict an organometallic CT lattice, Cu-dicyanobenzene (DCB), to be a stable QAH insulator. It exhibits ferromagnetic (FM) properties as a result of the charge transfer from metal atoms to DCB molecules. Moreover, based on the Ising model, the Curie temperature of the FM ordering is calculated to be around 100 K. Both the Chern numbers and the chiral edge states of the semi-infinite Cu-DCB edge structure, which occur inside the spin-orbit coupling band gap, confirm its nontrivial topological properties. These make the Cu-DCB CT lattice an ideal candidate to enrich the family of QAH insulators.

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Publication history

Received: 14 February 2020
Revised: 13 March 2020
Accepted: 22 March 2020
Published: 14 April 2020
Issue date: June 2020

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© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020

Acknowledgements

Work in China is supported by the National Natural Science Foundation of China (Nos. 51922011, 61888102, and 11974045), the National Key Research & Development Program of China (Nos. 2016YFA0202300, 2018YFA0305800, and 2019YFA0308500), the CAS Pioneer Hundred Talents Program, K. C. Wong Education Foundation, the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB30000000) and Beijing Institute of Technology Research Fund Program for Young Scholars. A portion of the research was performed in CAS Key Laboratory of Vacuum Physics. Computational resources were provided by the National Supercomputing Center in Tianjin. Work in the USA (S. B. Z.) was supported by U.S. DOE under Grant No. DE-SC0002623.

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Email: nanores@tup.tsinghua.edu.cn

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