AI 中文总结
研究单轴应变对单层Janus AsTeBr材料性能的影响，通过第一性原理等计算表明，应变可降低晶体对称性，产生有限BCD，诱导NLHE，还研究了应变依赖的光学性质，建立了对称破缺等之间微观联系，为调控材料多功能特性提供有效策略。
AI 中文摘要
非线性霍尔效应（NLHE）能在具有破缺反演对称性的非磁性材料中产生横向电荷电流，通过贝里曲率偶极子（BCD）保持时间反演对称性。然而，在具有\(C_{3v}\)对称性的晶体中，三重旋转对称性使BCD消失，抑制了本征NLHE。本文利用第一性原理密度泛函理论结合基于万尼尔函数的输运计算表明，单轴应变通过将晶体对称性从\(C_{3v}\)降低到\(C_{1}\)并产生有限BCD，在单层Janus AsTeBr中诱导出NLHE。贝里曲率热点的各向异性重新分布产生了明显的非线性霍尔电导率和电流，在2%拉伸应变时获得最大响应，并通过联合态密度等研究了应变依赖的光学性质，结果建立了对称破缺等之间的微观联系，表明单轴应变是调控Janus二维材料多功能特性的有效策略。
英文摘要
The nonlinear Hall effect (NLHE) enables the generation of a transverse charge current in nonmagnetic materials with broken inversion symmetry while preserving time-reversal symmetry through the Berry curvature dipole (BCD). However, in crystals with $C_{3v}$ symmetry, the threefold rotational symmetry forces the BCD to vanish, thereby suppressing the intrinsic NLHE despite the presence of finite local Berry curvature. Here, using first-principles density functional theory combined with Wannier-based transport calculations, we demonstrate that uniaxial strain induces the NLHE in monolayer Janus AsTeBr by lowering the crystal symmetry from $C_{3v}$ to $C_{1}$ and generating a finite BCD. The resulting anisotropic redistribution of Berry-curvature hotspots produces pronounced nonlinear Hall conductivity and nonlinear Hall current, with the maximum response obtained at 2\% tensile strain. To elucidate the accompanying electronic-structure evolution, we further investigate the strain-dependent optical properties through the joint density of states, dielectric function, optical absorption, and reflectance. The optical spectra exhibit a systematic red shift and enhanced low-energy interband transitions, consistent with the strain-induced reconstruction of the electronic structure. Our results establish a microscopic connection between symmetry breaking, Berry-phase geometry, nonlinear Hall transport, and optical response, demonstrating that uniaxial strain provides an effective strategy for tailoring multiple functional properties in Janus two-dimensional materials.
Comments11 pages, 13 figures
