We present the first investigation of unusual nonlinear Hall effects in twisted multilayer 2D materials. Contrary to expectations, our study shows that these nonlinear effects are not merely extensions of their monolayer counterparts. Instead, we find that stacking order and pairwise interactions between neighboring layers, mediated by Berry curvatures, play a pivotal role in shaping their collective nonlinear optical response. By combining large-scale Real-Time Time-Dependent Density Functional Theory (RT-TDDFT) simulations with model Hamiltonian analyses, we demonstrate a remarkable second-harmonic transverse response in hexagonal boron nitride four-layers, even in cases where the total Berry curvature cancels out. Furthermore, our symmetry analysis of the layered structures provides a simplified framework for predicting nonlinear responses in multilayer materials in general. Our investigation challenges the prevailing understanding of nonlinear optical responses in layered materials and opens new avenues for the design and development of advanced materials with tailored optical properties.

中文翻译：

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扭曲多层 2D 材料中的非常规非线性霍尔效应


我们首次研究了扭曲多层 2D 材料中不常见的非线性霍尔效应。与预期相反，我们的研究表明，这些非线性效应不仅仅是单层效应的延伸。相反，我们发现由 Berry 曲率介导的相邻层之间的堆叠顺序和成对交互在塑造它们的集体非线性光学响应中起着关键作用。通过将大规模实时时变密度泛函理论 （RT-TDDFT） 仿真与模型哈密顿分析相结合，我们证明了六方氮化硼四层中显着的二次谐波横向响应，即使在总 Berry 曲率抵消的情况下也是如此。此外，我们对多层结构的对称性分析为预测多层材料中的非线性响应提供了一个简化的框架。我们的研究挑战了对多层材料中非线性光学响应的普遍理解，并为设计和开发具有定制光学特性的先进材料开辟了新的途径。