论文标题
相关增强的旋转轨道耦合和量子异常霍尔绝缘子具有较大的带隙和稳定的单层稳定的铁磁性
Correlation-enhanced spin-orbit coupling and quantum anomalous Hall insulator with large band gap and stable ferromagnetism in monolayer $\mathrm{Fe_2Br_2}$
论文作者
论文摘要
非平凡的带拓扑结合磁有序可以产生量子异常的霍尔绝缘子（QAHI），这可能会导致设备概念的进步。在这里，通过第一原则计算，稳定的单层$ \ mathrm {fe_2br_2} $可以通过使用通用梯度近似以及$ u $ $ u $（gga+$ $ $ $ $ $）的方法来预测是一种室温大间隙高质量QAHI。较大的差距是由于Fe Atoms的相关增强的自旋轨道耦合（SOC）效应，该效应与无需电子相关的无需人工增加了SOC的强度。平面外磁各向异性是产生量子异常大厅（QAH）状态的非常关键，因为面内磁磁将破坏非平凡的带拓扑。在没有SOC的情况下，$ \ MATHRM {Fe_2Br_2} $是一个半狄拉克半学状态，受镜像对称性保护，电子相关性以及SOC效应创建了QAH状态，具有相当的间隙和两个手性边缘模式。发现QAH状态在单层$ \ Mathrm {Fe_2br_2} $中具有稳定的稳定的铁磁性（FM）订购和平面磁性方便性的单层$ \ mathrm {fe_2br_2} $中的双轴菌株（$ a/a_0 $：0.96至1.04）。计算结果表明，居里温度对相关强度和应变敏感。减少的相关性和压缩应变有利于高居里温度。这些分析和结果可以很容易地扩展到其他单层$ \ mathrm {fe_2xy} $（x/y = cl，br和i），该$ {fe_2br_2} $ monolayer具有相同的fe为主的低能状态。这些发现为设计新的高温拓扑量子设备开辟了新的机会。
Nontrivial band topology combined with magnetic ordering can produce quantum anomalous Hall insulator (QAHI), which may lead to advances in device concepts. Here, through first-principles calculations, stable monolayer $\mathrm{Fe_2Br_2}$ is predicted as a room-temperature large-gap high-Chern-number QAHI by using generalized gradient approximation plus $U$ (GGA+$U$) approach. The large gap is due to correlation-enhanced spin-orbit coupling (SOC) effect of Fe atoms, which equates with artificially increasing the strength of SOC without electronic correlation. Out-of-plane magnetic anisotropy is very key to produce quantum anomalous Hall (QAH) state because in-plane magneitization will destroy nontrivial band topology. In the absence of SOC, $\mathrm{Fe_2Br_2}$ is a half Dirac semimetal state protected by mirror symmetry, and the electronic correlation along with SOC effect creates QAH state with a sizable gap and two chiral edge modes. It is found that the QAH state is robust against biaxial strain ($a/a_0$: 0.96 to 1.04) in monolayer $\mathrm{Fe_2Br_2}$ with stable ferromagnetic (FM) ordering and out-of-plane magnetic anisotropy. Calculated results show that Curie temperature is sensitive to correlation strength and strain. The reduced correlation and compressive strain are in favour of high Curie temperature. These analysis and results can be readily extended to other monolayer $\mathrm{Fe_2XY}$ (X/Y=Cl, Br and I), which possesses the same Fe-dominated low-energy states with a $\mathrm{Fe_2Br_2}$ monolayer. These findings open new opportunities to design new high-temperature topological quantum devices.
