Tuning the topological and magnetic properties of materials by applying an electric field is widely used in spintronics. In this work, we find a topological phase transition from topologically trivial to nontrivial states at an external electric field of about 0.1 V/Å in a ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ monolayer that is a topologically trivial ferromagnetic semiconductor. It is shown that when electric field increases from 0 to 0.15 V/Å, the magnetic anisotropy energy (MAE) increases from about 0.1 to 6.3 meV, and the Curie temperature $T_C$ increases from 13 to about 61 K. The increased MAE mainly comes from the enhanced spin-orbit coupling due to the applied electric field. The enhanced $T_C$ can be understood from the enhanced $p\text{−}d$ hybridization and decreased energy difference between $p$ orbitals of Te atoms and $d$ orbitals of Mn atoms. Moreover, we propose two Janus materials, ${\mathrm{MnBi}}_2{\mathrm{Se}}_2{\mathrm{Te}}_2$ and ${\mathrm{MnBi}}_2{\mathrm{S}}_2{\mathrm{Te}}_2$ monolayers with different internal electric polarizations, which can realize the quantum anomalous Hall effect (QAHE) with Chern numbers $C=1$ and $C=2$, respectively. Our study not only exposes the electric field induced exotic properties of the ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ monolayer but also proposes materials to realize QAHE in ferromagnetic Janus semiconductors with electric polarization.

中文翻译：

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电场引起的二维铁磁半导体拓扑相变以及自旋轨道耦合和居里温度的大幅提高

通过施加电场来调整材料的拓扑和磁性能已广泛应用于自旋电子学中。在这项工作中，我们发现在大约0.1 V /Å的外部电场中，从拓扑琐碎状态到非琐碎状态的拓扑相变${\mathrm{锰铋}}_{\mathrm{2个}}{特}_4$单层，是拓扑上琐碎的铁磁半导体。结果表明，当电场从0增加到0.15 V /Å时，磁各向异性能（MAE）从大约0.1 meV增加到6.3 meV，居里温度${Ť}_C$从13 K增加到大约61K。MAE的增加主要是由于施加的电场导致自旋轨道耦合增强。增强型${Ť}_C$ 从增强可以理解 $p\text{-}d$ 杂交与降低之间的能量差 $p$ Te原子的轨道和 $d$Mn原子的轨道。此外，我们建议使用两种Janus材料，${\mathrm{锰铋}}_{\mathrm{2个}}{硒}_{\mathrm{2个}}{特}_{\mathrm{2个}}$ 和 ${\mathrm{锰铋}}_{\mathrm{2个}}{\mathrm{小号}}_{\mathrm{2个}}{特}_{\mathrm{2个}}$ 具有不同内部极化的单分子层，可以实现具有Chern数的量子异常霍尔效应（QAHE） $C=\mathrm{1个}$ 和 $C=\mathrm{2个}$， 分别。我们的研究不仅暴露了电场引起的外来特性。${\mathrm{锰铋}}_{\mathrm{2个}}{特}_4$ 单层膜，但也提出了在具有极化作用的铁磁Janus半导体中实现QAHE的材料。