反铁磁$MnTe$ - $Bi_2(Se, Te)_3$ - $MnTe$异质结构中Chern绝缘体和轴子绝缘体相的实现
Realization of the Chern insulator and Axion insulator phases in antiferromagnetic $MnTe$-$Bi_2(Se, Te)_3$-$MnTe$ heterostructures
摘要：
三维拓扑绝缘体薄膜的时间反演对称性破缺可以导致不同的拓扑量子相，如陈氏绝缘体（CI）相和轴子绝缘体（AI）相。使用第一性原理密度泛函理论方法，我们研究了这两个拓扑相的发病在一个三层异质结构组成的Bi $_2$ Se $_3$（Bi $_2$ Te $_3$）TI薄膜夹在两个反铁磁MnTe层。我们发现，一个正交的交换场从MnTe层，由一个小的各向异性势垒稳定，打开一个能隙的顺序为10毫电子伏的狄拉克点的TI膜。拓扑分析表明，取决于交换场在两个界面的相对取向，系统的总陈数是${\cal C} = 1$或${\cal C} = 0$，CI和AI相的特征，分别。由界面势引起的能隙区域内的非拓扑表面态使这种识别复杂化。然而，值得注意的是，异常霍尔电导率的计算表明，这种非拓扑表面状态不影响拓扑诱导的输运性质。鉴于交换间隙的大小，我们估计，无间隙的手征边缘状态，导致量子反常霍尔效应，应该出现在这些异质结构的侧壁上的宽度$\ge 200$ nm的CI相。我们还讨论了通过相邻导电层中的自旋霍尔效应引起的自旋-轨道矩诱导CI和AI相之间的转变的可能性。
英文摘要：
Breaking time-reversal symmetry in three-dimensional topological insulator thin films can lead to different topological quantum phases, such as the Chern insulator (CI) phase, and the axion insulator (AI) phase. Using first-principles density functional theory methods, we investigate the onset of these two topological phases in a tri-layer heterostructure consisting of a Bi$_2$Se$_3$ (Bi$_2$Te$_3$) TI thin film sandwiched between two antiferromagnetic MnTe layers. We find that an orthogonal exchange field from the MnTe layers, stabilized by a small anisotropy barrier, opens an energy gap of the order of 10 meV at the Dirac point of the TI film. A topological analysis demonstrates that, depending on the relative orientation of the exchange field at the two interfaces, the total Chern number of the system is either ${\cal C} = 1$ or ${\cal C} = 0$, characteristic of the CI and the AI phase, respectively. Non-topological surface states inside the energy-gap region, caused by the interface potential, complicate this identification. Remarkably though, the calculation of the anomalous Hall conductivity shows that such non-topological surface states do not affect the topology-induced transport properties. Given the size of the exchange gap, we estimate that gapless chiral edge states, leading to the quantum anomalous Hall effect, should emerge on the sidewalls of these heterostructures in the CI phase for widths $\ge 200$ nm. We also discuss the possibility of inducing transitions between the CI and the AI phases by means of the spin-orbit torque caused by the spin Hall effect in an adjacent conducting layer.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
