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Zhong Fang Topological insulator is a new state of quantum matter, characterized by topological invariants like Z or Z2 numbers. Exotic quantum phenomena, such as Majorana Fermions, magneto-electric effect, and quantum anomalous Hall effect, have been expected from topological insulators, while their experimental realizations remain challenging, due to the lack of suitable samples or requirement of extreme conditions. Within recent couple of years, more and more topological insulators were discovered, yet lots of new compounds still wait to be explored. In this talk, I will start from our earlier studies on Bi2Se3 family compounds, and discuss the characterization of topological nature from the Wannier representation and Willson loop method. I then move to the recent study for the topological aspect and quantum magnetoresistance of Ag2Te. The possible realization of quantized Anomalous Hall effect and Majorana fermions after breaking time reversal symmetry will be discussed from the view point of materials design. |