近日，南京大学王雷团队报道了菱面体薄石墨的跨维反常霍尔效应。2026年4月29日出版的《自然》杂志发表了这项成果。

反常霍尔效应（AHE）出现在时间反演对称性破缺的材料中，是磁有序与电子轨道运动之间相互作用的典型体现。在二维（2D）体系中，AHE与由面内手性轨道运动产生的面外轨道磁化耦合。在三维（3D）体系中，当样品厚度远大于垂直相干输运长度lz时，AHE 实际上是面外轨道磁化（源于面内轨道运动）的厚度平均化二维对应物。

研究组实验观察到了一种全新类型的AHE，该效应在多层层状菱方石墨烯中同时耦合了面内和面外轨道磁化，表现为在面内和面外磁场下均出现显著的霍尔电阻回滞。这一状态源于一种奇特的金属相，该相在电子-电子相互作用驱动下自发打破了时间反演对称性、镜像对称性和旋转对称性。

通过测量从3层到15层的多个器件，研究组发现该现象仅出现在2–5 nm的中等厚度范围。理论计算表明，在此厚度窗口内的载流子能够在二维平面内及跨平面方向维持相干的轨道运动。综合这些结果，研究组确定了一个介于二维和三维之间的未知“跨维度”区域，即样品厚度远大于原子间距但仍与lz相当，这正是这种新物质态——跨维度反常霍尔效应——出现的条件。该研究指明了一类独特的AHE，为跨维度景观的关联与拓扑物理开辟了新的探索模型。

附：英文原文

Title: Transdimensional anomalous Hall effect in rhombohedral thin graphite

Author: Li, Qingxin, Fan, Hua, Li, Min, Xu, Yinghai, Song, Junwei, Wang, Anqi, Watanabe, Kenji, Taniguchi, Takashi, Chen, Jing-Jing, Tan, Zhenbing, Shen, Jie, Jiang, Hua, Hone, James C., Dean, Cory R., Novoselov, Kostya S., Xie, Xin-Cheng, Yu, Geliang, Zhao, Yue, Liu, Jianpeng, Wang, Lei

Issue&Volume: 2026-04-29

Abstract: Anomalous Hall effect (AHE), occurring in materials with broken time-reversal symmetry, epitomizes the interplay between magnetic order and electron orbital motions1,2,3,4. In two-dimensional (2D) systems, AHE is coupled with out-of-plane orbital magnetization associated with in-plane chiral orbital motions. In three-dimensional (3D) systems, in which sample thickness far exceeds a vertical coherence-transport length lz, the AHE is effectively a thickness-averaged 2D counterpart4—still governed by out-of-plane orbital magnetization arising from in-plane orbital motions. Here we report the experimental observation of a fundamentally new type of AHE that couples both in-plane and out-of-plane orbital magnetizations in multilayer rhombohedral graphene, shown by pronounced Hall resistance hysteresis under both in-plane and out-of-plane magnetic fields. This state emerges from a peculiar metallic phase that spontaneously breaks time-reversal, mirror and rotational symmetries driven by electron–electron interactions. By measuring multiple devices spanning 3–15 layers, we find that this phenomenon emerges only within an intermediate thickness of 2–5nm. Theoretical calculations show that carriers within this window can sustain coherent orbital motions both within and across the 2D plane. Together, these identify an uncharted ‘transdimensional’ regime between 2D and 3D, in which the sample thickness is much larger than atomic spacing yet remains comparable to lz, for the emergence of this new state of matter—transdimensional AHE. Our findings point to a distinct class of AHE, opening an unexplored model for correlated and topological physics in transdimensional landscapes.

DOI: 10.1038/s41586-026-10471-1

Source: https://www.nature.com/articles/s41586-026-10471-1