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CAMP: From Topological Insulators to Quantum Anomalous Hall Effect

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Cui-Zu Chang, Massachusetts Institute of Technology
When
26 January 2016 from 3:30 PM to 4:30 PM
Where
339 Davey Laboratory
Contact Name
Moses Chan
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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. A QAH system carries spin-polarized dissipationless chiral edge transport channels without external energy input, hence may have huge impact on future electronic and spintronic device applications with ultralow-power consumption. The many decades’ quest for the experimental realization of QAH effect received a boost 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 [1]. In 2015, a near ideal system in V-doped TI, contrary to the expectation of first principle calculations, was demonstrated to show extremely high-precision QAH quantization with more robust magnetization and higher Curie temperature [2]. In this talk, I will introduce the route to the experimental observation of the QAH effect in above-mentioned two systems [1,2], and discuss the zero magnetic field dissipationless edge mode and the origin of the dissipative channels in the high-precision QAH state [3]. Finally I will outline the prospects and the barriers of a viable QAH-based device.

References

[1] Cui-Zu Chang et al, Science 340, 167(2013).

[2] Cui-Zu Chang et al, Nature Materials 14, 473(2015).

[3] Cui-Zu Chang et al, Physics Review Letters 115, 057206 (2015).

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