We theoretically propose that the monolayer ATiX family (KTiSb, KTiBi, RbTiSb, SrTiSn) are potential candidates for large-gap quantum anomalous Hall insulators with high Chern number C=2. Both of the topology and magnetism in these materials are from 3d-orbitals of Ti. We construct the tight-binding model with symmetry analysis to reveal the origin of topology. Remarkably, quite different from the conventional s-d band inversion, here the topological band inversion within 3d orbitals is due to the crystal field and electron hopping, while spin-orbit coupling only trivially gaps out the Dirac cone at Fermi level. The general physics from the 3d orbitals here applies to a large class of transition metal compounds with the space group P4/nmm or P-42m and their subgroups.
@article{arxiv.2211.08938,
title = {Large-Gap Quantum Anomalous Hall Insulators in $A$Ti$X$ Class},
author = {Yadong Jiang and Huan Wang and Jing Wang},
journal= {arXiv preprint arXiv:2211.08938},
year = {2023}
}