Speaker: Dr. Cui-Zu Chang
Description: The quantum anomalous Hall (QAH) effect can be considered as the quantum Hall (QH) effect without an 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 a 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 . 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 . In this talk, I will introduce the route to the experimental observation of the QAH effect in aforementioned two systems [3, 4], and talk about our recent progress on QAH sandwich heterostructures from the axion insulator physics and the topological Hall effect [5,6].
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 R. Yu et al, Science 329, 61 (2010).
 Cui-Zu Chang et al, Science 340, 167(2013).
 Cui-Zu Chang et al, Nat. Mater. 14, 473(2015).
 Di Xiao et al, Phys. Rev. Lett. 120, 056801 (2018).
 Jue Jiang et al, (2019, submitted).
Presentation Slides: Quantum Anomalous Hall Effect in Magnetic Topological Insulator Thin Films (PDF)