标题： 量子反常霍尔绝缘体中零霍尔平台的观察 显示英文标题

标题： Observation of the zero Hall plateau in a quantum anomalous Hall insulator

摘要： 量子反常霍尔（QAH）效应在磁性拓扑绝缘体（TI）中是一种新的输运现象，在没有外部磁场的情况下，霍尔电阻达到量子平台。 最近，这种奇特的效应已在Bi2Te3家族TI的超薄薄膜中自发铁磁（FM）有序中被实验发现。 关于QAH态的一个重要问题是，它是否仅仅是无磁场的量子霍尔（QH）效应，还是存在超越传统范式的新的物理现象。 在这里，我们报告了由于磁化反转导致的QAH绝缘体两个相反霍尔平台之间的量子相变的实验研究。 我们在矫顽力附近的磁场范围内观察到了一个定义明确的零霍尔电导平台，这与最近的理论预测一致。 零霍尔平台的特征显示与QAH效应密切相关，但其温度演化与传统QH平台跃迁的网络模型存在定量差异。 我们认为，存在于磁畴边界上的手性边缘态，这是QAH绝缘体特有的，是导致零霍尔平台的原因。 丰富的磁畴动力学使QAH效应成为一种独特的量子现象，可能在自旋电子学中找到新的应用。 显示英文摘要

摘要： Quantum anomalous Hall (QAH) effect in magnetic topological insulator (TI) is a novel transport phenomenon in which the Hall resistance reaches the quantum plateau in the absence of external magnetic field. Recently, this exotic effect has been discovered experimentally in an ultrathin film of the Bi2Te3 family TI with spontaneous ferromagnetic (FM) order. An important question concerning the QAH state is whether it is simply a zero-magnetic-field version of the quantum Hall (QH) effect, or if there is new physics beyond the conventional paradigm. Here we report experimental investigations on the quantum phase transition between the two opposite Hall plateaus of a QAH insulator caused by magnetization reversal. We observe a well-defined plateau with zero Hall conductivity over a range of magnetic field around coercivity, consistent with a recent theoretical prediction. The features of the zero Hall plateau are shown to be closely related to that of the QAH effect, but its temperature evolution exhibits quantitative differences from the network model for conventional QH plateau transition. We propose that the chiral edge states residing at the magnetic domain boundaries, which are unique to a QAH insulator, are responsible for the zero Hall plateau. The rich magnetic domain dynamics makes the QAH effect a distinctive class of quantum phenomenon that may find novel applications in spintronics.