论文标题
MNBI的拓扑表面状态$ _2 $ te $ _4 $在有限温度下和域墙壁
Topological surface states of MnBi$_2$Te$_4$ at finite temperatures and at domain walls
论文作者
论文摘要
MNBI $ _2 $ te $ _4 $最近是强化研究的主题，这是由于轴突绝缘子，Weyl半准和量子异常的霍尔绝缘子阶段的预测，具体取决于结构和磁性顺序。实验结果已经证实了这张图片的某些方面，但是几个实验使低温处的零间隙表面状态与预期冲突。在这项工作中，我们开发了基于第一原理的紧密结合模型，该模型可以任意控制局部旋转方向和自旋轨道耦合，从而使我们能够准确处理大型单位电池。使用此模型，我们检查了拓扑表面状态与温度的函数的行为，发现仅在Néel温度上方的间隙闭合。此外，我们检查了磁域对电子结构的影响，并发现域壁零间隙状态在许多单位电池上延伸。当许多域大小平均时，这些结构域壁状态可能看起来类似于高温拓扑表面状态，并可能通过实验来对待理论结果。
MnBi$_2$Te$_4$ has recently been the subject of intensive study, due to the prediction of axion insulator, Weyl semimetal, and quantum anomalous Hall insulator phases, depending on the structure and magnetic ordering. Experimental results have confirmed some aspects of this picture, but several experiments have seen zero-gap surfaces states at low temperature, in conflict with expectations. In this work, we develop a first-principles-based tight-binding model that allows for arbitrary control of the local spin direction and spin-orbit coupling, enabling us to accurately treat large unit-cells. Using this model, we examine the behavior of the topological surface state as a function of temperature, finding a gap closure only above the Néel temperature. In addition, we examine the effect of magnetic domains on the electronic structure, and we find that the domain wall zero-gap states extend over many unit-cells. These domain wall states can appear similar to the high temperature topological surface state when many domain sizes are averaged, potentially reconciling theoretical results with experiments.
