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arXiv 1406.7450cond-mat.str-elcond-mat.mtrl-sci
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铁磁拓扑绝缘体中反常霍尔效应向量子态的轨迹

Trajectory of Anomalous Hall Effect toward the Quantized State in a Ferromagnetic Topological Insulator

J. G. Checkelsky, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, Y. Kozuka, J. Falson, M. Kawasaki, Y. Tokura

摘要:

拓扑绝缘体是一种表面具有对称性保护的无隙模的块状电子绝缘体。打破表面模式的无隙性质的对称性,预计会产生奇异的新的物质状态。特别是,它最近已经预测和显示,打破时间反演对称性的铁磁性的形式可以引起一个带隙的状态,其特征在于零磁场量子化霍尔响应和无耗散的纵向传输称为量子反常霍尔(QAH)状态。迄今为止,实验上尚未探索的一个关键问题是这种新型量子霍尔态与先前已知的轨道驱动量子霍尔态的关系。在这里,我们实验表明,表现出QAH状态的铁磁拓扑绝缘体是很好地描述的全局相图的量子霍尔效应。通过映射QAH相附近的温度,磁场和化学势的参数空间中的电导率张量的行为,我们发现量子临界性和离域行为的证据,可以定量地描述的量子霍尔基态的重整化群属性。这一结果表明,在铁磁拓扑绝缘体中观察到的QAH态可以在控制量子霍尔态的对应态定律的上下文中理解。这为研究QAH效应提供了一个路线图,包括可能的相邻拓扑非平凡状态的过渡和QAH过渡的可能普适性类。

英文摘要:

Topological insulators are bulk electronic insulators which possess symmetry protected gapless modes on their surfaces. Breaking the symmetries that underlie the gapless nature of the surface modes is predicted to give rise to exotic new states of matter. In particular, it has recently been predicted and shown that breaking of time reversal symmetry in the form of ferromagnetism can give rise to a gapped state characterized by a zero magnetic field quantized Hall response and dissipationless longitudinal transport known as the Quantum Anomalous Hall (QAH) state. A key question that has thus far remained experimentally unexplored is the relationship of this new type of quantum Hall state with the previously known orbitally driven quantum Hall states. Here, we show experimentally that a ferromagnetic topological insulator exhibiting the QAH state is well described by the global phase diagram of the quantum Hall effect. By mapping the behavior of the conductivity tensor in the parameter space of temperature, magnetic field, and chemical potential in the vicinity of the QAH phase, we find evidence for quantum criticality and delocalization behavior that can quantitatively be described by the renormalization group properties of the quantum Hall ground state. This result demonstrates that the QAH state observed in ferromagnetic topological insulators can be understood within the context of the law of corresponding states which governs the quantum Hall state. This suggests a roadmap for studying the QAH effect including transitions to possible adjacent topologically non-trivial states and a possible universality class for the QAH transition.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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