As paradigmatic phenomena, Hall effects have inspired tremendous studies of symmetry and topology in condensed matter physics. Intriguingly, a second-order nonlinear Hall effect was recently proposed in noncentrosymmetric materials even in the presence of time-reversal symmetry. This effect originates from the Berry curvature dipole of electronic band structures and was predicted in Dirac and Weyl materials such as transition metal dichalcogenides and Weyl semimetals. Although it has been experimentally verified in some transition metal dichalcogenides, no obvious observation of such effects has been reported in Weyl semimetals. Taking advantage of the ideal Weyl phase with no coexisting trivial bands at the Fermi level, we use strained HgTe as a concrete example to show that the ideal Weyl semimetal is a promising platform for demonstrating the nonlinear Hall effect. Based on numerical calculations of the Berry curvature dipole, it was found that the magnitude of nonlinear Hall effect can be simply engineered by in-plane strain. Our work provides a versatile platform with high tunability, which could greatly facilitate the study of nonlinear Hall effect in three-dimensional topological materials.

中文翻译：

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HgTe 中的应变工程非线性霍尔效应

作为典型现象，霍尔效应激发了凝聚态物理中对称性和拓扑学的大量研究。有趣的是，最近在非中心对称材料中提出了二阶非线性霍尔效应，即使在存在时间反演对称的情况下也是如此。这种效应源于电子能带结构的贝里曲率偶极子，并且在 Dirac 和 Weyl 材料（如过渡金属二硫属化物和 Weyl 半金属）中得到了预测。尽管它已在一些过渡金属二硫属化物中得到实验验证，但在 Weyl 半金属中尚未报道明显观察到这种效应。利用在费米能级没有共存平凡带的理想外尔相，我们使用应变 HgTe 作为一个具体的例子来证明理想的外尔半金属是展示非线性霍尔效应的有希望的平台。基于贝里曲率偶极子的数值计算，发现非线性霍尔效应的大小可以通过面内应变简单地设计。我们的工作提供了一个具有高可调性的多功能平台，可以极大地促进三维拓扑材料中非线性霍尔效应的研究。