Visualization of Novel Electronic Structures in Topological Insulators

Three-dimensional (3D) topological insulators (TIs) represent a new state of quantum matter with a bulk gap generated by the spin-orbit interaction and an odd number of relativistic Dirac fermions on the surface. The unusual surface states of TIs can be the host for many striking quantum phenomena, such as an image magnetic monopole induced by an electric charge and Majorana fermions induced by the proximity effect from a superconductor.

By investigating these materials with angle-resolved photoemission spectroscopy (ARPES), we were able to directly visualize their non- trivial electronic structures. We will also show that the manipulation of these unusual topological surface states can further lead to other novel topological states, such as the quantized anomalous Hall state. Finally, we will briefly discuss the application potentials of these unusual materials, in electronics, spintronics and energy-related applications.