Fijalkowski Kajetan M, Liu Nan, Mandal Pankaj, Schreyeck Steffen, Brunner Karl, Gould Charles, Molenkamp Laurens W
Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany.
Institute for Topological Insulators, Am Hubland, D-97074, Würzburg, Germany.
Adv Sci (Weinh). 2023 Aug;10(22):e2303165. doi: 10.1002/advs.202303165. Epub 2023 Jun 14.
The recent advent of topological states of matter spawned many significant discoveries. The quantum anomalous Hall (QAH) effect is a prime example due to its potential for applications in quantum metrology, as well as its influence on fundamental research into the underlying topological and magnetic states and into axion electrodynamics. Here, electronic transport studies on a (V,Bi,Sb) Te ferromagnetic topological insulator nanostructure in the QAH regime are presented. This allows access to the dynamics of an individual ferromagnetic domain. The domain size is estimated to be in the 50-100 nm range. Telegraph noise resulting from the magnetization fluctuations of this domain is observed in the Hall signal. Careful analysis of the influence of temperature and external magnetic field on the domain switching statistics provides evidence for quantum tunneling (QT) of magnetization in a macrospin state. This ferromagnetic macrospin is not only the largest magnetic object in which QT is observed, but also the first observation of the effect in a topological state of matter.
拓扑物态的近期出现催生了许多重大发现。量子反常霍尔（QAH）效应就是一个典型例子，这是由于它在量子计量学中的应用潜力，以及它对基础拓扑和磁态以及轴子电动力学研究的影响。在此，展示了对处于QAH regime的（V，Bi，Sb）Te铁磁拓扑绝缘体纳米结构的电子输运研究。这使得能够研究单个铁磁畴的动力学。估计畴尺寸在50 - 100纳米范围内。在霍尔信号中观察到由该畴的磁化涨落引起的电报噪声。仔细分析温度和外部磁场对畴开关统计的影响，为宏观自旋态下磁化的量子隧穿（QT）提供了证据。这种铁磁宏观自旋不仅是观察到QT的最大磁性物体，也是在拓扑物态中首次观察到该效应。
