Dr. Madhab
Neupane
Princeton University, Princeton, New
Jersey
Los Alamos National Laboratory, Los Alamos,
New Mexico
A three-dimensional
(3D) Z2 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 non-trivial topological invariants. Not only did the 3D Z2 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 and Weyl 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 realization of these new phases of matter in real materials by momentum
and time-resolved photoemission spectroscopy. The unusual properties of the
protected topological surface states can lead to future applications in
spintronics and quantum computation, which hold promise to revolutionize our
electronics and energy industries.
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