The 5d transition heavy elements with large spin-orbit coupling (SOC) effect can induce a large magnetic anisotropy energy (MAE) in magnetic materials. Meanwhile, the asymmetric occupation of 5d orbital electrons in transition metal trihalides can also trigger interesting orbital ordering. Here, the electronic structure and magnetic properties of two-dimensional (2D) OsI₃ monolayer were investigated by first-principles calculations. The OsI₃ monolayer has two orbital orderings with low spin states, where the half-metallic state is an Ising ferromagnet with a Curie temperature (T_C) of 208 K and a perpendicular magnetic anisotropy (PMA) of −45.8 meV, but the Mott insulator state has an in-plane magnetic anisotropy (IMA) of 13.7 meV. The half-metallic state included non-self-consistent SOC calculations opens a band gap of 118.3 meV, showing a quantum anomalous Hall effect (QAHE) with a Chern number (C) of −1. A topologically trivial band gap opened in self-consistent SOC calculations, where QAHE of C = −2 can be realized by shifting Fermi surface. The in-plane biaxial strain can significantly tailor the MAE of the half-metallic state, yielding a PMA of −33.0 and −50.7 meV at a compressive strain of 6% and −2%. Meanwhile, T_C rises to 275 K at a tensile strain of 6%. The transition between Mott insulator and half-metallic states can also be regulated by strain. These findings suggest that OsI₃ monolayer is promising for 2D magnetism and spintronics.

具有大自旋轨道耦合（SOC）效应的5 d过渡重元素可以在磁性材料中产生大的磁各向异性能量（MAE）。同时，过渡金属三卤化物中 5 d轨道电子的不对称占据也可以引发有趣的轨道排序。在这里，通过第一性原理计算研究了二维（2D）OsI ₃单层的电子结构和磁性。OsI ₃单层具有两个低自旋态的轨道排序，其中半金属态是具有居里温度（T _C) 为 208 K，垂直磁各向异性 (PMA) 为 -45.8 meV，但莫特绝缘体状态的面内磁各向异性 (IMA) 为 13.7 meV。包含非自洽 SOC 计算的半金属态打开了 118.3 meV 的带隙，显示出陈数 ( C ) 为 -1的量子反常霍尔效应 (QAHE) 。在自洽 SOC 计算中打开了一个拓扑微不足道的带隙，其中C  = -2 的 QAHE 可以通过移动费米表面来实现。面内双轴应变可以显着调整半金属态的 MAE，在 6% 和 -2% 的压缩应变下产生 -33.0 和 -50.7 meV 的 PMA。同时_，TC在 6% 的拉伸应变下升至 275 K。莫特绝缘体和半金属状态之间的转变也可以通过应变来调节。这些发现表明，OsI ₃单层对于二维磁性和自旋电子学很有前景。