Nonlinear Responses in van der Waals Topological Materials

The quantum geometrical structure of electron wavefunctions, characterized by quantum metric and Berry curvature, can significantly influence electron behavior. Recently, these properties have been found to be closely linked to nonlinear electromagnetic responses. In 2D van der Waals materials, symmetry, chemical potential, and band geometry can be easily tuned by gating, displacement fields, stacking, and strain, making these systems ideal for studying nonlinear responses and their quantum geometric origins. In this talk, I will present several examples of nonlinear responses in 2D vdW materials.