Berry Curvature Enhanced Nonlinear Photogalvanic Response of Type-II Weyl Cone

In this talk, signatures of the singular topology in a type-II Weyl semimetal TaIrTe₄ is revealed in the photo responses, which are shown to be directly related to the divergence of Berry curvature. As a result of the divergence of Berry curvature at the Weyl nodes, TaIrTe₄ exhibits unusually large photo responsivity of 130.2 mA/W with 4-mm excitation in an unbiased field effect transistor at room temperature arising from the third-order nonlinear optical response. Furthermore, the circularly polarized galvanic response is also enhanced at 4-mm, possibly due to the same Berry curvature singularity enhancement with the shift current. Considering the optical selection rule of Weyl cones with opposite chirality, it may open new experimental possibilities for studying and controlling the chiral polarization of Weyl Fermions through an in-plane DC electric field in addition to the optical helicities.