Sass Paul M, Kim Jinwoong, Vanderbilt David, Yan Jiaqiang, Wu Weida
Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2020 Jul 17;125(3):037201. doi: 10.1103/PhysRevLett.125.037201.
Here, we present microscopic evidence of the persistence of uniaxial A-type antiferromagnetic order to the surface layers of MnBi_{2}Te_{4} single crystals using magnetic force microscopy. Our results reveal termination-dependent magnetic contrast across both surface step edges and domain walls, which can be screened by thin layers of soft magnetism. The robust surface A-type order is further corroborated by the observation of termination-dependent surface spin-flop transitions, which have been theoretically proposed decades ago. Our results not only provide key ingredients for understanding the electronic properties of the antiferromagnetic topological insulator MnBi_{2}Te_{4}, but also open a new paradigm for exploring intrinsic surface metamagnetic transitions in natural antiferromagnets.
在这里，我们使用磁力显微镜展示了单轴A型反铁磁序在MnBi₂Te₄单晶表面层持续存在的微观证据。我们的结果揭示了跨表面台阶边缘和畴壁的与终止相关的磁对比度，这可以被软磁薄层屏蔽。通过对与终止相关的表面自旋翻转转变的观察，进一步证实了稳健的表面A型序，这在几十年前就已在理论上被提出。我们的结果不仅为理解反铁磁拓扑绝缘体MnBi₂Te₄的电子特性提供了关键要素，还为探索天然反铁磁体中的本征表面变磁转变开辟了新的范式。
