Photoemission Studies of Topological Superconducting Materials

A three-dimensional (3D) topological insulator (TI) is a crystalline solid, which is an insulator in the bulk but features spin-polarized Dirac electron states on its surface. In 2007, the first 3D TI was discovered in a bismuth-based compound. The discovery of the first TI tremendously accelerated research into phases of matter characterized by nontrivial topological invariants. Not only did the 3D TI itself attract great research interest, it also inspired the prediction of a range of new topological phases of matter. Primary examples include the topological Kondo insulator, the topological 3D Dirac, Weyl, and nodal-line semimetals, the topological crystalline insulator, and the topological superconductor. Specifically, recent predictions have claimed that long-sought-out Majorana fermions can be realized at the interface between a topological insulator and a superconductor and may shift our scientific trajectory from research to applications in topological quantum computing. In this talk, I will discuss the electronic properties of topological superconducting materials obtained by using momentum-, spin-, and time-resolved photoemission spectroscopy. Developing our understanding of topological superconducting materials will guide us on a path to realize the properties of Majorana fermion quasiparticle states associated with topological superconductivity.