近日，美国波士顿学院的Ilija Zeljkovic及其研究团队取得一项新进展。经过不懈努力，他们揭示金属中自旋贝里曲率增强的轨道塞曼效应。相关研究成果已于2024年4月22日在国际知名学术期刊《自然—物理学》上发表。

该研究团队在双层笼目金属TbV₆Sn₆中，发现了一个源自拓扑的巨大轨道塞曼效应。借助光谱成像扫描隧道显微镜，研究人员观察到磁场作用下，原本具有能隙的狄拉克色散分裂成两个分支，这一现象伴随着动量依赖g因子的增强，导致狄拉克能带发生了显著的重整化。这些测量提供了一个磁场控制的轨道塞曼耦合到轨道磁矩的直接观察，特别是在有能隙狄拉克点附近，观测到的轨道磁矩高达200个玻尔磁子。

这项研究不仅深入揭示了拓扑轨道矩的动量依赖性质，还展示了其通过磁场进行调控的可能性，同时伴随着自旋贝里曲率的演化过程。这些结果可以扩展到探索由自旋以外的，其他量子数控制的贝里曲率驱动的大轨道磁矩，例如某些石墨烯基结构中的谷。

据悉，贝里相和相关的贝里曲率概念可以在固体中产生许多非常规现象。

附：英文原文

Title: Spin Berry curvature-enhanced orbital Zeeman effect in a kagome metal

Author: Li, Hong, Cheng, Siyu, Pokharel, Ganesh, Eck, Philipp, Bigi, Chiara, Mazzola, Federico, Sangiovanni, Giorgio, Wilson, Stephen D., Di Sante, Domenico, Wang, Ziqiang, Zeljkovic, Ilija

Issue&Volume: 2024-04-22

Abstract: Berry phases and the related concept of Berry curvature can give rise to many unconventional phenomena in solids. Here, we discover a colossal orbital Zeeman effect of topological origin in a bilayer kagome metal, TbV₆Sn₆. Using spectroscopic imaging scanning tunnelling microscopy, we reveal that the magnetic field leads to a splitting of the gapped Dirac dispersion into two branches with enhanced momentum-dependent g factors, resulting in a substantial renormalization of the Dirac band. These measurements provide a direct observation of a magnetic field-controlled orbital Zeeman coupling to the orbital magnetic moments of up to 200Bohr magnetons near the gapped Dirac points. Our work provides direct insight into the momentum-dependent nature of topological orbital moments and their tunability via the magnetic field, concomitant with the evolution of the spin Berry curvature. These results can be extended to explore large orbital magnetic moments driven by the Berry curvature governed by other quantum numbers beyond spin, such as the valley in certain graphene-based structures.

DOI: 10.1038/s41567-024-02487-z

Source: https://www.nature.com/articles/s41567-024-02487-z