Third-order nonlinear Hall effects (THE) have recently attracted considerable experimental interest as powerful probes for quantum geometric properties in emergent quantum materials, encompassing quadrupole moments of quantum metric and Berry curvature. Here, we report a fundamentally new THE in room-temperature van der Waals ferromagnet Fe3GaTe2 from second-order Berry connection polarizability, which manifests a higher-order characterization of band geometry called symplectic connection. Our observations show that the third-order transverse response in Fe3GaTe2 is odd to magnetization, vanishes above the Curie temperature and remains independent of driving current directions. Scaling law analysis combined with first-principles calculations establishes this response as the symplectic-connection-induced THE. This discovery opens the door to probing high-order quantum geometric properties beyond Berry curvature and quantum metric through nonlinear transport, unveiling the potential of exploring nonlinear Hall phenomena in broad classes of magnets without breaking inversion symmetry. Moreover, the room-temperature manipulation of THE holds promises for device applications based on harnessing the quantum-geometric connection structure.
@article{arxiv.2604.20356,
title = {Symplectic connection third-order Hall effect in a room-temperature ferromagnet},
author = {Yu Cao and Xukun Feng and Yiming Guo and Huiying Liu and Qia Shen and Hongliang Chen and Wanxi Gong and Yu Yang and Dandan Guan and Yaoyi Li and Shiyong Wang and Hao Zheng and Canhua Liu and Xiaoxue Liu and Yumeng Yang and Xuepeng Qiu and Ruidan Zhong and Jinfeng Jia and Shengyuan A. Yang and Cong Xiao and Liang Liu},
journal= {arXiv preprint arXiv:2604.20356},
year = {2026}
}
Comments
The submitted version for review on April 30, 2025. 22 pages, 5 figures