Nevola D, Li H X, Yan J-Q, Moore R G, Lee H-N, Miao H, Johnson P D
Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2020 Sep 11;125(11):117205. doi: 10.1103/PhysRevLett.125.117205.
Surface magnetism and its correlation with the electronic structure are critical to understanding the topological surface state in the intrinsic magnetic topological insulator MnBi_{2}Te_{4}. Here, using static and time resolved angle-resolved photoemission spectroscopy (ARPES), we find a significant ARPES intensity change together with a gap opening on a Rashba-like conduction band. Comparison with a model simulation strongly indicates that the surface magnetism on cleaved MnBi_{2}Te_{4} is the same as its bulk state. The inability of surface ferromagnetism to open a gap in the topological surface state uncovers the novel complexity of MnBi_{2}Te_{4} that may be responsible for the low quantum anomalous Hall temperature of exfoliated MnBi_{2}Te_{4}.
表面磁性及其与电子结构的相关性对于理解本征磁性拓扑绝缘体MnBi₂Te₄中的拓扑表面态至关重要。在此，我们使用静态和时间分辨角分辨光电子能谱（ARPES），发现在类Rashba导带上有明显的ARPES强度变化以及能隙打开。与模型模拟的比较有力地表明，解理后的MnBi₂Te₄的表面磁性与其体态相同。表面铁磁性无法在拓扑表面态中打开能隙，揭示了MnBi₂Te₄的新奇复杂性，这可能是导致剥落的MnBi₂Te₄的量子反常霍尔温度较低的原因。
