IUPAP C-10 Award Talk: From Topological Insulators to Quantum Anomalous Hall Effect

The quantum anomalous Hall (QAH) effect can be considered as the quantum Hall (QH) effect without external magnetic field, which can be realized by time reversal symmetry breaking in a topologically non-trivial system [1, 2]. A QAH system carries spin-polarized dissipationless chiral edge transport channels without the need for external energy input, hence may have huge impact on future electronic and spintronic device applications for ultralow-power consumption. The many decades quest for the experimental realization of QAH phenomenon became a possibility in 2006 with the discovery of topological insulators (TIs). In 2013, the QAH effect was observed in thin films of Cr-doped TI for the first time [3]. Two years later in a near ideal system, V-doped TI, contrary to the negative prediction from first principle calculations, a high-precision QAH quantization with more robust magnetization and a perfectly dissipationless chiral current flow was demonstrated [4]. In this talk, I will introduce the route to the experimental observation of the QAH effect in above-mentioned two systems [3, 4], and discuss the zero magnetic field dissipationless edge current flow as well as the origin of the dissipative channels in the QAH state [5]. Finally I will talk about our recent progress on the QAH insulator-Anderson insulator quantum phase transition and its scaling behaviors [6]. References [1] F. D. M. Haldane, Phys. Rev. Lett. 61, 2015-2018 (1988). [2] R. Yu et al, Science 329, 61-64 (2010). [3] Cui-Zu Chang et al, Science 340, 167(2013). [4] Cui-Zu Chang et al, Nature Materials 14, 473(2015). [5] Cui-Zu Chang et al, Physics Review Letters 115, 057206 (2015). [6] Cui-Zu Chang et al, Physics Review Letters 117, 126802 (2016)..