AI 中文总结
本研究在理论上提出两种途径，通过交错势或垂直磁场，使交替磁体的拓扑平庸态转变为陈数分别为1或2的拓扑交替磁相，实现量子反常霍尔态，为实验提供了可行方案。
AI 中文摘要
我们从理论上提出了在交替磁体材料中实现量子反常霍尔态的两种可能途径。我们考虑了一个最小的正方晶格哈伯德模型，该模型具有与正交晶体结构相关的反对称自旋-轨道耦合，它支持拓扑上平庸的交替磁态。通过引入Rashba型自旋-轨道耦合和外部扰动，我们证明了这种平庸态可以通过两种不同方式转变为拓扑交替磁相。第一种途径由交错势驱动，它破坏了连接晶体学等价子晶格的对称性，产生了以量子化霍尔电导率|σₓᵧ|=e²/h和陈数C=1为特征的拓扑交替磁基态。第二种途径通过施加垂直于二维平面的磁场实现，产生的拓扑态作为磁滞回线中的亚稳态出现，其量子化霍尔电导率|σₓᵧ|=2e²/h，对应陈数C=2。我们表明，这些拓扑转变伴随布里渊区边界处的特征能隙关闭，能隙关闭点的数量决定了陈数。带几何计算揭示了与体拓扑不变量一致的手性边缘态，并证明了C=1和C=2态之间存在不同的自旋极化。我们的结果为实验上实现交替磁体中的量子反常霍尔响应建立了可行的途径。
英文摘要
We theoretically propose two possible routes to realizing quantum anomalous Hall states in altermagnetic materials. We consider a minimal square-lattice Hubbard model with antisymmetric spin-orbit coupling associated with an orthorhombic crystal structure, which supports a topologically trivial altermagnetic state. By incorporating Rashba-type spin-orbit coupling and external perturbations, we demonstrate that this trivial state can be turned into topological altermagnetic phases in two distinct ways. The first route is driven by a staggered potential that breaks the symmetry connecting crystallographically equivalent sublattices, leading to a topological altermagnetic ground state characterized by a quantized Hall conductivity $\left| σ_{xy} \right|=e^2/h$ and a Chern number $C=1$. The second route is realized by applying a magnetic field perpendicular to the two-dimensional plane. The resulting topological state appears as a metastable state in the magnetic hysteresis loop, exhibiting a quantized Hall conductivity $\left| σ_{xy} \right|=2e^2/h$ associated with a Chern number $C=2$. We show that these topological transitions are accompanied by characteristic gap closings at the Brillouin-zone boundary, with the number of gap-closing points determining the Chern number. Ribbon-geometry calculations reveal chiral edge states consistent with the bulk topological invariants and demonstrate distinct spin polarizations between the $C=1$ and $C=2$ states. Our results establish experimentally accessible routes to quantized anomalous Hall responses in altermagnets.
Comments10 pages, 6 figures
