Quantum Hall effect (QHE), a quantized version of Hall effect, was observed in two-dimensional electron systems more than 30 years ago [1-3], in which the Hall resistance is quantized into h/e2 plateaus (h is Planck's constant, e the electron's charge, and  is an integer [1] or a certain fraction [2]). Occurrence of QHE relies on the formation of well-defined Landau levels, thus is only possible in high mobility samples and strong external magnetic fields.
In this talk, I report the experimental realization of quantum anomalous Hall effect (QAHE) [4], a quantized version of anomalous Hall effect, in thin films of Cr-doped (Bi,Sb)2Te3 magnetic topological insulator [5, 6] grown by molecular beam epitaxy. At zero magnetic field, the gate-tuned anomalous Hall resistance exhibits a quantized value of h/e2 accompanied by a significant drop of the longitudinal resistance. The longitudinal resistance vanishes under a strong magnetic field whereas the Hall resistance remains at the quantized value. I will also discuss about possible opportunities in Majorana fermions detection and less-power-consumption electronics based on QAHE.

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5. M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
6. X. L. Qi and S. C. Zhang, Rev. Mod. Phys. 83, 1057 (2011).