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Unconventional responses upon breaking discrete or crystal symmetries open avenues for exploring emergent physical systems and materials. By breaking inversion symmetry, a nonlinear Hall signal can be observed, even in the presence of time-reversal symmetry, quite different from the conventional Hall effects. However, less is known when a strong nonlinear Hall signal can be measured, in particular, its connections with the band-structure properties. By using model analysis, we find prominent nonlinear Hall signals near tilted band anticrossings and band inversions [1]. These band signatures can be used to explain the strong nonlinear Hall effect in the recent experiments on two-dimensional WTe2 [2]. Disorder plays indispensable roles in various linear Hall effects. We derive the formulas of the nonlinear Hall conductivity in the presence of disorder scattering and construct the general scaling law of the nonlinear Hall effect, which may help in experiments to distinguish disorder-induced contributions to the nonlinear Hall effect [3].
Fig. 1 Schematic of how to measure the nonlinear Hall effect in a standard Hall bar. The experimentally measured I−V relation is related to the theoretical Berry dipole defined by the electric field-current density (E−J) relation.
参考文献:
[1] Zongzheng Du, Chunming Wang, HZL*, Xincheng Xie, PRL 121, 266601 (2018).
[2] Qiong Ma, Su-Yang Xu, Liang Fu, Gedik, Pablo Jarillo-Herrero et al., Nature 565, 337 (2019).
[3] Zongzheng Du, Chunming Wang, Shuai Li, HZL*, Xincheng Xie, arXiv:1812.08377, Nature Commun. (2019)
Hai-Zhou Lu obtained his Ph.D. in Physics from Institute for Advanced Study, Tsinghua University, Beijing, in 2007. From 2007 to 2015, he was a Postdoc and then Research Assistant Professor at the University of Hong Kong. He is now a Professor of Physics at Southern University of Science and Technology, Shenzhen, China. His research is focused on the quantum transport in topological states of matter.