发表机构
Indian Institute of Technology Guwahati; Bilkent University（印度理工学院古瓦哈提分校; 比尔肯特大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究针对具有高赝自旋费米子的应变莫尔结构，通过调控 onsite 质量与扭转角θ绘制相图，利用应变打破C₃对称性激活贝里曲率偶极子，实现了幅度显著高于过渡金属二硫化物的大非线性霍尔效应，为低温拓扑识别提供了重要工具。
AI 中文摘要
我们研究莫尔“水车晶格”的线性与非线性霍尔响应，该晶格的堆叠与扭转会在费米能级附近产生四能带流形，且在离散魔角处群速度被抑制。引入打破层间对称性的 onsite 质量（ onsite 质量即 onsite 项的质量参数），会在该流形中打开能隙，驱动系统进入非平凡的体拓扑相。我们绘制了该相图随质量强度与扭转角θ的变化关系，揭示出多个具有高陈数的区域。随后引入应变以打破晶格剩余的C₃对称性，这会激活有限的贝里曲率偶极子，进而产生非线性霍尔响应。该偶极子在拓扑相边界处符号急剧反转，在相关系统参数下绘制时呈现类蝴蝶特征，其幅度显著高于对称性破缺的过渡金属二硫化物的报道值，这与晶格赝自旋-3/2特征对应的升高的威尔逊环缠绕数和增强的量子几何一致。最后我们纳入贝里曲率偶极子的热效应，确认其是低温下识别拓扑性质的重要工具。
英文摘要
We investigate the linear and nonlinear Hall response of a moiré \emph{watermill lattice}, in which stacking and twisting generate a four-band manifold near the Fermi level with suppressed group velocities at discrete magic angles. Including an inversion symmetry breaking onsite mass breaks the interlayer symmetry, opening a gap in this manifold and driving the system into a non-trivial bulk topological phase. We map the resulting phase diagram as a function of the strength of the mass and twist angle $θ$, revealing several sectors with high Chern numbers. We then introduce strain to break the residual $C_3$ symmetry of the lattice which activates a finite Berry curvature dipole and correspondingly, a nonlinear Hall response. The dipole reverses sign sharply across topological phase boundaries, producing butterfly like features when plotted against the relevant system parameters. Its magnitude substantially exceeds that reported for symmetry-broken transition metal dichalcogenides, consistent with the elevated Wilson-loop winding and enhanced quantum geometry associated with the lattice's pseudospin-$3/2$ character. We conclude by incorporating thermal effects on the Berry curvature dipole, asserting that it is an important tool for discerning topology at low temperatures.
Comments15 pages, 12 figures
