arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.13783cond-mat.mes-hallcond-mat.mtrl-sci
收藏

磁无序诱导的量子反常霍尔基态

Distinct quantum anomalous Hall ground states induced by magnetic disorders

Chang Liu, Yunbo Ou, Yang Feng, Gaoyuan Jiang, Weixiong Wu, Shaorui Li, Zijia Cheng, Ke He, Xucun Ma, Qikun Xue, Yayu Wang

摘要:

磁性拓扑绝缘体(TI)中的量子反常霍尔(QAH)效应代表了拓扑与磁性相互作用产生的一种新的物质状态。QAH基态的定义特性是在没有外部磁场的情况下的量子化霍尔电阻率($ρ_{yx}$)和消失纵向电阻率($ρ_{xx}$)。关于QAH效应的一个基本问题是,它是否仅仅是一个零磁场量子霍尔(QH)效应,或者它是否可以拥有独特的量子相位和相变,这是在其他地方无法获得的。QAH系统与其他QH系统最显著的区别在于强磁无序引起的空间随机磁化。由于无序和磁性在二维电子系统的相图中起着关键作用,QAH系统中的高度磁性无序可能会产生新的相位和量子临界现象。在这项工作中,我们进行了系统的输运研究的一系列磁TI与不同强度的磁紊乱。我们发现QAH效应的基态可以分为两类:QAH绝缘体相和反常Hall(AH)绝缘体相,它们分别对应于QH系统中的QH液体相和Hall绝缘体相。在低无序极限的QAH绝缘体制度,我们观察到一个普遍的量子化纵向电阻$ρ_{xx} = h/e^{2}$在矫顽场。在AH绝缘体区,我们发现磁场可以驱动它通过量子临界点到QAH绝缘体相,其标度行为与QH相变中的标度行为不同。我们认为,在畴界处的手征边缘态之间的传输是确定QAH基态的关键,而这种传输可以通过无序和磁场来调节。

英文摘要:

The quantum anomalous Hall (QAH) effect in magnetic topological insulator (TI) represents a new state of matter originated from the interplay between topology and magnetism. The defining characteristics of the QAH ground state are the quantized Hall resistivity ($ρ_{yx}$) and vanishing longitudinal resistivity ($ρ_{xx}$) in the absence of external magnetic field. A fundamental question concerning the QAH effect is whether it is merely a zero-magnetic-field quantum Hall (QH) effect, or if it can host unique quantum phases and phase transitions that are unavailable elsewhere. The most dramatic departure of the QAH systems from other QH systems lies in the strong magnetic disorders that induce spatially random magnetization. Because disorder and magnetism play pivotal roles in the phase diagram of two-dimensional electron systems, the high degree of magnetic disorders in QAH systems may create novel phases and quantum critical phenomena. In this work, we perform systematic transport studies of a series of magnetic TIs with varied strength of magnetic disorders. We find that the ground state of QAH effect can be categorized into two distinct classes: the QAH insulator and anomalous Hall (AH) insulator phases, as the zero-magnetic-field counterparts of the QH liquid and Hall insulator in the QH systems. In the low disorder limit of the QAH insulator regime, we observe a universal quantized longitudinal resistance $ρ_{xx} = h/e^{2}$ at the coercive field. In the AH insulator regime, we find that a magnetic field can drive it to the QAH insulator phase through a quantum critical point with distinct scaling behaviors from that in the QH phase transition. We propose that the transmission between chiral edge states at domain boundaries, tunable by disorder and magnetic fields, is the key for determining the QAH ground state.

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。

↑