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arXiv · 2203.08770

Manipulation of Dirac band curvature and momentum-dependent g-factor in a kagome magnet YMn6Sn6

Hong Li·He Zhao·Kun Jiang·Qi Wang·Qiangwei Yin·Ning-Ning Zhao·Kai Liu·Ziqiang Wang·Hechang Lei·Ilija Zeljkovic
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Abstract

The Zeeman effect describes the energy change of an atomic quantum state in magnetic field. The magnitude and the direction of this change depend on the dimensionless Lande g-factor. In quantum solids, the response of the Bloch electron states to the magnetic field also exhibits the Zeeman effect with an effective g-factor that was theoretically predicted to be dependent on the momentum. While typically negligible in many ordinary solids, the momentum-dependent variation of the g-factor is theorized to be substantially enhanced in many topological and magnetic systems. However, the momentum-dependence of the g-factor is notoriously difficult to extract and it is yet to be directly experimentally measured. In this work, we report the experimental discovery of a strongly momentum-dependent g-factor in a kagome magnet YMn6Sn6. Using spectroscopic-imaging scanning tunneling microscopy, we map the evolution of a massive Dirac band in the vicinity of the Fermi level as a function of magnetic field. We find that electronic states at different lattice momenta exhibit markedly different Zeeman energy shifts, giving rise to an anomalous g-factor that peaks around the Dirac point. Our work provides the first momentum-resolved visualization of Dirac band curvature manipulation by magnetic field, which should in principle be highly relevant to other topological kagome magnets.

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Hong Li, He Zhao, Kun Jiang, Qi Wang, Qiangwei Yin, Ning-Ning Zhao, Kai Liu, Ziqiang Wang, Hechang Lei, Ilija Zeljkovic. 2022-03-16. Manipulation of Dirac band curvature and momentum-dependent g-factor in a kagome magnet YMn6Sn6. https://doi.org/10.1038/s41567-022-01558-3

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