kagome金属中由可调自旋-Berry曲率驱动的巨大轨道Zeeman效应
Colossal orbital Zeeman effect driven by tunable spin-Berry curvature in a kagome metal
AI总结：
在新合成kagome金属TbV6Sn6中，利用扫描隧道显微镜观测到磁场控制的巨大轨道Zeeman效应，高达200玻尔磁子的轨道磁矩由非平庸自旋-Berry曲率产生，为动量依赖的拓扑轨道磁矩及其磁场可调性提供了首个直接实验证据。
摘要：
Berry相位及相关的Berry曲率概念能在固体中引发许多非常规现象。在本研究中，我们在新合成的双层kagome金属TbV6Sn6中发现了拓扑起源的巨大轨道Zeeman效应。我们利用光谱成像扫描隧道显微镜研究了磁场诱导的能带结构重整化。非磁性的钒d轨道在K点形成Dirac交叉，具有小质量间隙以及由自旋-轨道耦合诱导的强Berry曲率。我们揭示了磁场导致带隙Dirac色散分裂为两个分支，并具有巨大的动量依赖g因子，从而导致Dirac能带的实质性重整化。这些测量提供了对磁场控制的轨道Zeeman耦合的直接观察，该耦合作用于带隙Dirac点附近高达200玻尔磁子的巨大轨道磁矩。有趣的是，该效应表现出越来越强的非线性，并在更高磁场下逐渐被抑制。理论建模进一步证实了TbV6Sn6中轨道磁矩的存在，它们由Bloch波函数的非平庸自旋-Berry曲率产生。我们的研究为动量依赖的拓扑轨道磁矩本质、其通过磁场伴随自旋-Berry曲率演化的可调性提供了首个直接见解。由Berry曲率驱动的显著大轨道磁矩也可由自旋以外的其他量子数产生，例如某些基于石墨烯结构中的能谷，这可以使用我们工作中强调的相同工具来揭示。
英文摘要：
Berry phase and the related concept of Berry curvature can give rise to many unconventional phenomena in solids. In this work, we discover colossal orbital Zeeman effect of topological origin in a newly synthesized bilayer kagome metal TbV6Sn6. We use spectroscopic-imaging scanning tunneling microscopy to study the magnetic field induced renormalization of the electronic band structure. The nonmagnetic vanadium d-orbitals form Dirac crossings at the K point with a small mass gap and strong Berry curvature induced by the spin-orbit coupling. We reveal that the magnetic field leads to the splitting of gapped Dirac dispersion into two branches with giant momentum-dependent g factors, resulting in the substantial renormalization of the Dirac band. These measurements provide a direct observation of the magnetic field controlled orbital Zeeman coupling to the enormous orbital magnetic moments of up to 200 Bohr magnetons near the gapped Dirac points. Interestingly, the effect is increasingly non-linear, and becomes gradually suppressed at higher magnetic fields. Theoretical modeling further confirms the existence of orbital magnetic moments in TbV6Sn6 produced by the non-trivial spin-Berry curvature of the Bloch wave functions. Our work provides the first direct insight into the momentum-dependent nature of topological orbital moments and their tunability by magnetic field concomitant with the evolution of the spin-Berry curvature. Significantly large orbital magnetic moments driven by the Berry curvature can also be generated by other quantum numbers beyond spin, such as the valley in certain graphene-based structures, which may be unveiled using the same tools highlighted in our work.
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