Dirac plasmons and beyond: The past, present, and future of plasmonics in 3D topological insulators

We review progress studying unique plasmonics in topological insulators (TIs). First, we describe exfoliation and deposition synthesis approaches. TI materials have substantially improved: it is now possible to grow samples with few trivial electrons and controllable doping. We then describe the theory behind the unique behavior of the coupled, 2D Dirac plasmons. While reviewing experimental efforts, we note that Dirac plasmons have been conclusively demonstrated in TIs and they show remarkable properties including long lifetimes, large mode indices, and huge modulation depths. Finally, we describe the opportunities that are present now that high-quality materials can be obtained, including spin and nanoparticle plasmons.