Topological Insulators and Beyond: A Photoemission Investigation

 Abstract

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. The primary examples are the topological Kondo insulator, the topological 3D Dirac, Weyl and nodal-line semimetals, the topological crystalline insulator and the topological superconductor. Each of these phases was predicted to exhibit surface states with unique properties protected by a non-trivial topological invariant.

In this talk, I will discuss the experimental realizations of these new phases of matter in real materials through momentum-, spin- and time-resolved photoemission spectroscopy. The unusual properties of protected topological surface states can lead to future applications in spintronics and quantum computation.

BIO

Dr. Madhab Neupane received his Ph.D. in Physics from Boston College, Boston, MA in 2010. He spent four years (2011-2014) as a postdoctoral research associate at Princeton University, Princeton, NJ and one year (2015-2016) as a Director’s Fellow at Los Alamos National Laboratory, Los Alamos, NM. He joined University of Central Florida in 2016 as an Assistant Professor. His research focuses on the electronic and spin properties of new quantum materials such as Dirac and Weyl materials. He utilizes various spectroscopic techniques to reveal interesting electronic and spin properties as well as the momentum resolved dynamical properties of the bulk and symmetry-protected properties of the surface of these quantum materials.