TMC21: Unique electromagnetic properties of topological semimetals and insulators (Tutorial)

Topological Matter Conference (TMC) 2021: Unique electromagnetic properties of topological semimetals and insulators (Tutorial)
By Joel E. Moore, University of California, Berkeley

This talk starts by reviewing known examples of how topological materials generate new kinds of electrodynamic couplings and effects. Three-dimensional topological insulators realize a particular electromagnetic coupling known as “axion electrodynamics”, and understanding this leads to an improved understanding of magnetoelectricity in all materials. We then turn to how topological Weyl and Dirac semimetals can show unique electromagnetic responses; we argue that in linear response the main observable effect solves an old problem via the orbital moment of Bloch electrons, and how in nonlinear optics there should be a new quantized effect, which may have been seen experimentally. This nonlinear effect has a natural quantum e^3/h^2 and appears in chiral Weyl semimetals over a finite range of frequencies. We discuss interaction and disorder corrections to nonlinear responses in closing, which clarify the significant differences between topological responses in metals and insulators.

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The Topological Matter Conference (TMC) focuses on recent developments in fundamental and applied aspects of broad classes of topological quantum systems and the synergy between them. Topics include topological insulators and Weyl semimetals, topological phononics and photonics, skyrmions, quantum metrology and more.

The TMC is a joint effort between the H2020 FET-PROACTIVE projects TOCHA (GA: 824140) and SKYTOP (GA: 824123) with the objective to establish synergies and to mobilize the Topological Matter community. Intended to lead to an annual gathering, the first TMC will be celebrated in 2021 from June 28th to July 2nd. If the pandemic situation allows it, the conference will be hosted at the Eden Roc hotel in Sant Feliu de Guixols, Spain, including Plenary, Invited, Oral and Poster contributions. Otherwise, the conference will be virtual, likely with no poster presentations.