准一维Bi$_4$I$_4$中电场诱导的贝里曲率偶极子
Electric field induced Berry curvature dipole in quasi-one-dimensional Bi$_4$I$_4$
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中文总结 AI 辅助
研究少层Bi$_4$I$_4$在电场下的非线性霍尔响应，通过第一性原理计算，在对称性分析指导下追踪BCD张量演化，发现双层结构场致能带变化使BCD幅度增强，确立准一维铋卤化物为工程非线性霍尔响应的有前景平台。
中文摘要 AI 辅助
时间反演对称材料中的非线性霍尔效应为量子几何提供了有力探测手段。本文通过对少层Bi$_4$I$_4$的α相和β相进行全面的第一性原理计算，研究其电场可调谐的非线性霍尔响应。在对称性分析指导下，追踪面外电场下单层到双层结构的贝里曲率偶极子（BCD）张量演化。单层具有高刚性能带结构和适度的BCD可调性，双层则有显著的场致能带变化，包括β相中的渐进 Rashba 分裂和最终能隙闭合。关键是，这种场可调性使BCD幅度相对于单层大幅增强。研究结果确立了准一维铋卤化物作为工程非线性霍尔响应的有前景平台。
英文摘要
The nonlinear Hall effect in time-reversal symmetric materials offers a powerful probe into quantum geometry. Here, we investigate the electric-field-tunable nonlinear Hall response in few-layer $\text{Bi}_4\text{I}_4$ using comprehensive first-principles calculations across both its $α$ and $β$ phases. Guided by symmetry analysis, we track the evolution of the Berry curvature dipole (BCD) tensor from the monolayer to the bilayer configuration under an out-of-plane electric field. While the monolayer features a highly rigid band structure and modest BCD tunability, the bilayer architecture exhibits substantial field-induced band modifications, including a progressive Rashba splitting and eventual gap closure in the $β$ phase. Crucially, this field-tunability allows substantial enhancement of the BCD magnitude relative to the monolayer counterpart. Our findings establish quasi-one-dimensional bismuth halogenides as a promising platform for engineering nonlinear Hall response.
