Event Description
Darius H Torchinsky, PhD, Temple University
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, negative magnetoresistance, 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 observation of a
quantized photogalvanic effect in the structurally chiral Weyl semimetal RhSi
measured using nonlinear optical techniques that reports its topological charge
directly and also share our ongoing spectroscopic studies of the second
harmonic generation response of this material. |
