Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 43: Focus Session: Topology in 3D Reciprocal Space: Beyond Dirac and Weyl Quasiparticles (joint session TT/MA)

TT 43.1: Hauptvortrag

Mittwoch, 3. April 2019, 15:00–15:30, H2

Novel optical and electrical responses in topological semimetals — •Joel Moore — University of California, Berkeley, USA — Lawrence Berkeley National Laboratory, Berkeley, USA

Several new classes of topological materials have been confirmed to exist in experiments over the past decade. Many of these materials support unique electromagnetic properties that affect transport and optical responses in potentially useful ways. For example, topological insulators support a particular electromagnetic coupling known as "axion electrodynamics", and understanding this leads to an improved understanding of magnetoelectricity in all materials. The main focus of this talk is on how topological Weyl and Dirac semimetals can show unique electromagnetic responses; we argue that in linear response the main observable property solves an old problem about optical rotation via the orbital moment of Bloch electrons. Nonlinear responses such as magnetoconductivity can reveal more surprising behavior. Nonlinear optical response (second-harmonic generation) is already known to be remarkably strong in existing Weyl materials, and may show an unexpected strength and quantization in Weyl materials without mirror symmetries.

Talk includes results obtained with Fernando de Juan, Adolfo Grushin, Takahiro Morimoto, Joseph Orenstein, Daniel Parker, Ivo Souza, and Shudan Zhong.