Jing-Yang You¹, Zhen Zhang¹, Bo Gu^2,3,*, and Gang Su^1,2,3,†

¹School of Physical Sciences, University of Chinese Academy of Sciences, 100049 Beijng, China

²Kavli Institute for Theoretical Sciences, and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190 Beijing, China

³Physical Science Laboratory, Huairou National Comprehensive Science Center, 101400 Beijing, China

  To obtain room-temperature ferromagnetic semiconductors and to realize the room-temperature quantum anomalous Hall effect (QAHE) have been big challenges for a long time. Here we report that, on the basis of first-principles calculations, ${\mathrm{Pd}\mathrm{Br}}_3$ , ${\mathrm{Pt}\mathrm{Br}}_3$ , ${\mathrm{Pd}I}_3$ , and ${\mathrm{Pt}I}_3$ monolayers are ferromagnetic semiconductors that could exhibit a high-temperature QAHE. The Curie temperatures estimated by Monte Carlo simulations are 350 and 375 K for ${\mathrm{Pd}\mathrm{Br}}_3$ and ${\mathrm{Pt}\mathrm{Br}}_3$ monolayers, respectively. The band gaps of ${\mathrm{Pd}\mathrm{Br}}_3$ and ${\mathrm{Pt}\mathrm{Br}}_3$ are found to be 58.7 and 28.1 meV, respectively, with the generalized-gradient approximation and 100.8 and 45 meV, respectively, with the HSE06 method, being quite well in favor of observing the room-temperature QAHE. It is shown that the large band gaps are induced from multiorbital electron correlations. By carefully studying the stabilities of the four aforementioned monolayers, we unveil that they could be feasible for use in experiments. The present work sheds light on the development of spintronic devices by use of room-temperature ferromagnetic semiconductors and the implementation of dissipationless devices by application of the room-temperature QAHE.