Light-enhanced nonlinear Hall effect

The Hall response can be dramatically different from its quantized value in materials with broken inversion symmetry. This stems from the leading Hall contribution beyond the linear order, known as the Berry curvature dipole (BCD). While the BCD is in principle always present, it is typically very small outside of a narrow window close to a topological transition and is thus experimentally elusive without careful tuning of external fields, temperature, or impurities. We transcend this challenge by devising optical driving and quench protocols that enable practical and direct access to large BCD. Varying the amplitude of an incident circularly polarized laser drives a topological transition between normal and Chern insulator phases, and importantly allows the precise unlocking of nonlinear Hall currents comparable to or larger than the linear Hall contributions. This strong BCD engineering is even more versatile with our two-parameter quench protocol, as demonstrated in our experimental proposal. In this work, the authors investigate nonlinear Hall materials under optical driving. They find that nonlinear Hall materials can exhibit a strong light-enhanced nonlinear Hall response when excited by circularly polarized lasers.