The quantum level interplay between geometry, topology, and correlation is at the forefront of fundamental physics. Owing to the unusual lattice geometry and breaking of time-reversal symmetry, kagome magnets are predicted to support intrinsic Chern quantum phases. However, quantum materials hosting ideal spin-orbit coupled kagome lattices with strong out-of-plane magnetization have been lacking. Here we use scanning tunneling microscopy to discover a new topological kagome magnet TbMn6Sn6, which is close to satisfying the above criteria. We visualize its effectively defect-free purely Mn-based ferromagnetic kagome lattice with atomic resolution. Remarkably, its electronic state exhibits distinct Landau quantization upon the application of a magnetic field, and the quantized Landau fan structure features spin-polarized Dirac dispersion with a large Chern gap. We further demonstrate the bulk-boundary correspondence between the Chern gap and topological edge state, as well as the Berry curvature field correspondence of Chern gapped Dirac fermions. Our results point to the realization of a quantum-limit Chern phase in TbMn6Sn6, opening up an avenue for discovering topological quantum phenomena in the RMn6Sn6 (R = rare earth element) family with a variety of magnetic structures. Our visualization of the magnetic bulk-boundary-Berry correspondence covering real and momentum space demonstrates a proof-of-principle method revealing topological magnets.
Chern-Simons orbital magnetoelectric coupling in generic insulators
在第一性原理密度泛函理论的框架下，提出了一种基于Wannier的计算Chern-Simons轨道磁电耦合的方法.鉴于最近的发展与强大的Z2拓扑绝缘体，我们预计，陈-西蒙斯的贡献的磁电耦合，在特殊情况下，可以是一样大或大于总磁电耦合在已知的磁电像Cr2 O3。对普通的Cr_2O_3，BiFeO_3和GdAlO_3磁电体的计算结果证实了在这些情况下Chern-Simons贡献是很小的。另一方面，我们表明，如果空间反转和时间反转对称性的Z2拓扑绝缘体Bi 2 Se 3的手被打破，大的诱导变化出现在陈-西蒙斯磁电耦合。
Ferroelectric Altermagnetic Chern Insulator in magnetic field: electrical control of the Chern number
International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；Department of Physics, University of Guilan（吉兰大学物理系）
Magnetic-field-induced robust zero Hall plateau state in MnBi$_2$Te$_4$ Chern insulator
本征反铁磁拓扑绝缘体MnBi 2 Te 4为探索奇异拓扑量子现象提供了一个理想的平台。近年来，在低磁场区，少层MnBi_2Te_4器件中实现了Chern绝缘体相和轴子绝缘体相。然而，MnBi_2 Te_4在强磁场中的命运还没有在实验中探索过。在这项工作中，我们报告的剥离MnBi 2 Te 4薄片在脉冲磁场高达61.5 T的输运研究。在高场极限下，Chern数C = -1的Chern绝缘体相演化为鲁棒的零霍尔电阻平台态。非局域输运测量和理论计算表明，在强磁场中，零霍尔平台态的电荷输运是由朗道能级和大塞曼效应共同作用产生的两个反向传播的边缘态进行的.我们的结果表明，复杂的相互作用之间的内在磁秩序，外部磁场，和非平凡的能带拓扑结构MnBi 2 Te 4。
Even-Odd Layer-Dependent Exchange Bias Effect in MnBi2Te4 Chern Insulator Devices
The Pennsylvania State University（宾夕法尼亚州立大学）；Nanjing University（南京大学）；Nankai University（南开大学）；National Institute for Materials Science（国立材料研究所）；Oak Ridge National Laboratory（橡树岭国家实验室）；University of California, Riverside（加州大学河滨分校）
Magnetization-tuned topological quantum phase transition in MnBi2Te4 devices
近年来，内禀磁性拓扑绝缘体MnBi 2 Te 4由于在实现量子反常霍尔效应（QAHE）、轴子绝缘体态、高Chern数高温Chern绝缘体态等奇异拓扑量子态方面的巨大成功，引起了人们极大的研究兴趣。该领域的一个关键问题是有效地操纵这些状态并控制拓扑相变。在这里，通过系统的角度相关的输运测量，我们揭示了一个磁化调谐的拓扑量子相变从陈绝缘体的磁性绝缘体与带隙的狄拉克表面态的MnBi 2 Te 4设备。具体地，当磁场远离面外方向倾斜大约40-60度时，霍尔电阻偏离量化值，并且检测到巨大的各向异性磁阻。基于修正的Landauer-Buttiker理论的理论分析表明，场倾斜驱动的铁磁态到倾斜反铁磁态的转变在MnBi 2 Te 4器件中引起了从Chern绝缘体到具有带隙Dirac表面态的磁绝缘体的拓扑量子相变.我们的工作为拓扑量子态和拓扑量子相变的调制提供了一种有效的手段。
Hydrostatic Pressure-enhanced correlated magnetism and Chern insulator in moir'e WSe2
State Key Laboratory of Micro-nano Engineering Science, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院微纳工程科学国家重点实验室人工结构量子控制教育部重点实验室）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）；Center for High Pressure Science & Technology Advanced Research (HPSTAR)（高压科学与技术前沿研究中心）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments, Institute for Shanghai Advanced Research in Physical Sciences（上海极端环境材料前沿研究重点实验室上海物理科学研究院）；Zhiyuan College, Shanghai Jiaotong University（上海交通大学致远学院）；Research Center for Electronic and Optical Materials, National Institute for Materials Science（国立材料研究所电子与光学材料研究中心）；Research Center for Materials Nanoarchitectonics, National Institute for Materials Science（国立材料研究所材料纳米架构研究中心）；Hefei National Laboratory（合肥国家实验室）；Shanghai Research Center for Quantum Sciences（上海量子科学研究与创新中心）；Department of Physics and Astronomy, University of Tennessee, Knoxville（田纳西大学诺克斯维尔分校物理与天文系）；Department of Physics, National University of Singapore（新加坡国立大学物理系）
