Laser-induced hole coherence and spatial self-phase modulation in anisotropic 3D Weyl semimetal TaAs

Laser-induced electron coherence has been fascinating in manipulating quantum materials. Recently, it has been shown that laser-induced electron coherence in two-dimensional (2D) materials can lead to a third-order nonlinear optical response spatial self-phase modulation (SSPM), based on which novel all-optical switching scheme has been innovated. However, so far such investigations are mainly on electron coherence, whereby laser-induced hole coherence is rarely explored. Here, we report on the observation of optical Kerr effect in three-dimensional (3D) Weyl semimetal TaAs flakes. Nonlinear susceptibility χ⁽³⁾ is obtained, exhibiting a surprisingly high value (with = 9.9×10^-9 e.s.u. or 1.4×10^-16 m²/V² at 532 nm), which cannot be explained by the conventional electron mobility, but can be well understood by TaAs’s unique high anisotropic hole mobility. The Wind Chime Model and the -carrier mobility correlation can well explain the results, suggesting the crucial role of laser-induced non-local ac hole coherence. Our finding extends the understanding of SSPM from 2D to 3D quantum materials with anisotropic carrier mobility, and from electron coherence to hole coherence.