富Mn的MnSb $_2$ Te $_4$是一种铁磁拓扑绝缘体，具有最高的居里温度T_C = 45-50 K。它在拓扑表面态的狄拉克点处具有磁隙，磁隙在T_C以上消失。通过扫描隧道光谱，我们探测这个差距在不同的磁场和温度。我们首先揭示了间隙尺寸收缩，当施加高达B = 3 T的面内磁场时，但是由于磁化仅部分地在面内旋转而不完全闭合。这证实了磁隙的起源和复杂的磁结构。此外，我们还证明了在低至T_C/2的温度下能隙尺寸的时空涨落，高于T_C/2的温度时，回复磁化确实衰减。这个温度是接近的反铁磁转变温度观察到的块状型单晶的MnSb $_2$ Te $_4$，突出的重要作用，竞争的磁性订单形成有利的铁磁拓扑绝缘体。因此，我们的研究为拓扑绝缘体的复杂磁隙开口提供了至关重要的见解，这对量子反常霍尔器件具有决定性意义。
英文摘要：
Mn-rich MnSb$_2$Te$_4$ is a ferromagnetic topological insulator with yet the highest Curie temperature T_C = 45-50 K. It exhibits a magnetic gap at the Dirac point of the topological surface state that disappears above T_C. By scanning tunneling spectroscopy, we probe this gap at different magnetic fields and temperatures. We firstly reveal that the gap size shrinks, when an in-plane magnetic field of up to B = 3 T is applied, but does not close completely as the magnetization is only partially rotated in-plane. This corroborates the magnetic origin of the gap and the complex magnetic structure. In addition, we demonstrate significant spatiotemporal fluctuations of the gap size at temperatures as low as T_C/2, above which the remanent magnetization indeed decays. This temperature is close to the antiferromagnetic transition temperature observed for bulk-type single crystals of MnSb$_2$Te$_4$, highlighting the important role of competing magnetic orders in the formation of the favorable ferromagnetic topological insulator. Our study, thus, provides crucial insights into the complex magnetic gap opening of topological insulators that is decisive for quantum anomalous Hall devices.
Ferromagnetic van der Waals compound MnSb$_{1.8}$Bi$_{0.2}$Te$_4$
拓扑学和磁学的交叉点代表了发现新的量子现象和器件概念的新天地。在这项工作中，我们表明，范德华化合物MnSb $_{1.8}$ Bi $_{0.2}$ Te $_4$表现出铁磁基态的居里温度为26 K，在反铁磁秩序以前发现的Mn（Sb，Bi）$_2$ Te $_4$家庭的其他成员。我们采用磁输运，体磁化和中子散射的研究，以说明磁和电性能的MnSb $_{1.8}$ Bi $_{0.2}$ Te $_4$和一个不寻常的异常霍尔效应的观察报告。我们的结果是合成和理解铁磁拓扑绝缘体的重要一步。
Probing GHz Spin Dynamics Across Magnetic Phase Transitions in CrCl3 Nanoflakes Using Nitrogen-Vacancy Microscopy
University of Nebraska-Lincoln（内布拉斯加大学林肯分校）；Wichita State University（威奇托州立大学）；Nebraska Center for Materials and Nanoscience（内布拉斯加材料纳米科学中心）；University of Latvia（拉脱维亚大学）
Probing Interfacial Spin Dynamics and Temperature Dependent Asymmetry in Spin Pumping Across Ni80Fe20/Cu/Cr1.12Te2 Interfaces
Department of Physics, Indian Institute of Technology Kanpur（印度坎普尔理工学院物理系）；Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University（南洋理工大学国立教育学院自然科学与科学教育）
Probing valley quantum oscillations via the spin Seebeck effect in transition metal dichalcogenide/ferromagnet hybrids
Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences（中国科学院大学）；Waseda Institute for Advanced Study, Waseda University（早稻田大学）；CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences（中国科学院大学）；Advanced Science Research Center, Japan Atomic Energy Agency（日本原子能机构）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所）
Tunneling magnetoresistance devices based on topological insulators: Ferromagnet/insulator/topological-insulator junctions employing Bi$_{2}$Se$_{3}$
本文从理论上研究了三维拓扑绝缘体Bi $_{2}$ Se $_{3}$的隧穿磁电阻（TMR）器件。基于Bi $_{2}$ Se $_{3}$的现实紧束缚模型进行理论计算。我们研究了利用Bi $_{2}$ Se $_{3}$的表面态的三维器件，以及利用薄Bi $_{2}$ Se $_{3}$条的边缘态的二维器件。我们证明了Bi $_{2}$ Se $_{3}$的材料性质允许在室温下的TMR比为1000%的量级。分析公式推导出，允许在这些设备中实现的TMR比的快速估计。该装置可用于测量自旋极化的拓扑表面状态作为替代自旋ARPES。与基于磁性隧道结的TMR器件不同，本器件避免使用其磁化需要被钉扎的第二铁磁电极。
Probing Quantum Anomalous Hall States in Twisted Bilayer WSe2 via Attractive Polaron Spectroscopy
Joint Quantum Institute (JQI), University of Maryland（马里兰大学联合量子研究所）；Electrical Engineering Department, University of Maryland（马里兰大学电气工程系）；Center for Functional Nanomaterials, Brookhaven National Laboratory（布鲁克海文国家实验室功能纳米材料中心）
