Intrinsic time-reversal-odd nonlinear Hall effect determined solely by Bloch band geometry has attracted extensive interests since the theoretical proposal of combining it with antiferromagnetic spintronics and the experimental observations in few-layer MnBiTe₄. However, possible extrinsic contributions and their interplay with the intrinsic one have not been understood. Moreover, even the concept of nonlinear “intrinsic” contribution itself is still unclear, which has led to very recent theoretical and experimental debates. I will first introduce our recent work on the scaling law for time-odd second order nonlinear transport [1], which provides a basic tool for data analysis in low-frequency experiments. Then I will show some new understandings on the concept of nonlinear intrinsic transport and the prediction of high-frequency isolation of intrinsic response in a specific material [2].

[1] Y.-X. Huang, C. Xiao*, S. A. Yang*, and X. Li*, arXiv:2311.01219

[2] C. Xiao*, J. Cao, Q. Niu, and S. A. Yang, to appear on arXiv