ABSTRACT
Since the theoretical prediction of the existence of topological insulators (TIs) [1-5], there have been widespread interests in these remarkable materials. Both two-dimensional (2D) and three-dimensional (3D) TIs have been experimentally observed and veried [6-11]. A distinctive feature of this class of new quantum state of materials is its electronic density of states, which consists of insulating bulk bands and metallic edge (2D) or surface (3D) bands. Figure 21.1 shows the electronic band structure characteristics of Bi2Se3 measured by angle-resolved photoemission spectroscopy [12]. Data shown are from References 9 and 13 and modied in Reference 12. The Dirac cone is the hallmark of TIs.
