Pressure-dependent nonlinear optical response from TaAs

The topological Weyl semimetal TaAs is a polar metal that has recently been shown to exhibit a giant optical second harmonic response at infrared frequencies. In this talk, I will present hydrostatic pressure-dependent second harmonic generation rotational anisotropy measurements from TaAs single crystals using a diamond anvil cell based setup. Across a pressure-tuned tetragonal-to-hexagonal structural phase transition, we observe pronounced changes in both the magnitude and symmetry of the second harmonic generation signal, which are dictated primarily by the presence or absence of a polar axis. Potential application of this technique to other materials will be discussed.