近日，美国哈佛大学的Su-Yang Xu及其研究团队取得一项新进展。经过不懈努力，他们揭示了拓扑反铁磁异质结构中的量子度规非线性霍尔效应。相关研究成果已于2023年6月15日在国际权威学术期刊《科学》上发表。

该研究团队报道了一种与黑磷相互作用的偶数层MMnBi₂Te₄诱导的量子度规非线性霍尔效应。该效应在反转反铁磁（AFM）自旋时会改变方向，并表现出独特的尺度关系，与散射时间无关。这一研究结果为实验上发现理论上预测的量子度规响应打开了新的可能性，并为将非线性电子学与反铁磁自旋电子学结合应用提供了新的途径。

据悉，在凝聚态物理中，量子几何学包含两个分量：实部的量子度规和虚部的贝里曲率。虽然贝里曲率的效应已经通过二维电子气中的量子霍尔效应和铁磁体中的异常霍尔效应等现象得到观察，但对量子度规的影响却很少进行探索。

附：英文原文

Title: Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure

Author: Anyuan Gao, Yu-Fei Liu, Jian-Xiang Qiu, Barun Ghosh, Thaís V. Trevisan, Yugo Onishi, Chaowei Hu, Tiema Qian, Hung-Ju Tien, Shao-Wen Chen, Mengqi Huang, Damien Bérubé, Houchen Li, Christian Tzschaschel, Thao Dinh, Zhe Sun, Sheng-Chin Ho, Shang-Wei Lien, Bahadur Singh, Kenji Watanabe, Takashi Taniguchi, David C. Bell, Hsin Lin, Tay-Rong Chang, Chunhui Rita Du, Arun Bansil, Liang Fu, Ni Ni, Peter P. Orth, Qiong Ma, Su-Yang Xu

Issue&Volume: 2023-06-15

Abstract: Quantum geometry in condensed matter physics has two components: the real part quantum metric and the imaginary part Berry curvature. Whereas the effects of Berry curvature have been observed through phenomena such as the quantum Hall effect in 2D electron gases and the anomalous Hall effect (AHE) in ferromagnets, quantum metric has rarely been explored. Here, we report a nonlinear Hall effect induced by quantum metric dipole by interfacing even-layered MnBi₂Te₄ with black phosphorus. The quantum metric nonlinear Hall effect switches direction upon reversing the AFM spins and exhibits distinct scaling that is independent of the scattering time. Our results open the door to discovering quantum metric responses predicted theoretically and pave the way for applications that bridge nonlinear electronics with AFM spintronics.

DOI: adf1506

Source: https://www.science.org/doi/10.1126/science.adf1506