At the heart of the Weyl semimetal are massless, chiral quasiparticles that derive from electronic band-crossings split by either spatial inversion or time-reversal symmetry breaking. The resulting nodal points in the bulk band structure serve as sources and sinks of units of Berry curvature or “topological charge” that are responsible for the phenomenology usually associated with these materials, including open Fermi arc surface states and the chiral anomaly. However, Weyl semimetals with acentric crystal structures can also support second order nonlinear optical responses that reveal their unique band structure in surprising ways. In this talk, I will discuss our recent work using laser-driven currents in an attempt to try to study this topological charge directly, as well as our experiments on the Fermi arc surface states that reveal an unexpected degree of symmetry in the material response.
Zoom link will be forwarded to Condensed Matter Seminar email list. For a copy of the link or to be added to the email list, please contact Stephen Bullwinkel (bullwink@illinois.edu).
Recordings of Condensed Matter Seminar events can be found on mediaspace: https://mediaspace.illinois.edu/channel/Condensed%2BMatter%2BSeminar%2BTalks%2BFall%2B2020/178724052