Nonlinear Probing of Structural and Electronic Phase Transition in 2D Quantum Materials

2D quantum materials have demonstrated a plethora of novel physical properties with complex structural and electronic phase transition and potential applications. It is thus highly desirable to understand the underlying mechanism associated with those phase transitions. In this talk, I will report our recent theoretical effort on predicting nonlinear responses in 2D quantum materials, demonstrating nonlinear probe for structural and electronic phase transition, and showing the promise for quantum nonlinear electronics. Specifically, I will present microscopic theory of ferroelectric nonlinear Hall effect in time-reversal invariant layered topological materials and discuss the complex interplay of symmetry, electronic structure, and Berry curvature, and briefly report the experimental demonstration of Berry curvature memory effect as a high-order multiferroicity. Second, I will also present our recent theoretical work on magnetic shift photocurrent and magnetic injection photocurrent as the counterparts of normal shift current and normal injection current in time-reversal symmetry and inversion symmetry broken systems, and demonstrate how these nonlinear photocurrent responses can help decipher magnetic structures and interactions which could be particularly fruitful for probing and understanding magnetic topological quantum materials and phase transition.