Giant anisotropic nonlinear optical response in Weyl semimetals

摘要

The response of a material to applied intense radiation is characterized by its nonlinear optical susceptibility. While the conventional microscopic picture of nonlinear optics of materials involves expressions using higher order perturbation theory, recent theoretical studies have established a link between nonlinear optics and geometrical properties of the electronic wavefunction. Weyl semimetals are a recently discovered class of materials with nontrivial band structure geometry. We use optical second harmonic generation to measure the second order nonlinear optical response of Weyl semimetals of the transition metal monopnictide (TMMP) family. We find that the TMMP compounds have the largest measured nonlinear optical susceptibility of any bulk crystalline materials, with a susceptibility nearly an order of magnitude higher than that of other nonlinear optical materials.