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

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.

arXiv commentFinal accepted version will appear in Nature Physics

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Cited by in corpus (17)

• Topological kagome magnets and superconductors
• Abundant lattice instability in kagome metal ScV${}_6$Sn${}_6$
• Quantum Interactions in Topological R166 Kagome Magnet
• Plethora of tunable Weyl fermions in kagome magnet Fe3Sn2 thin films
• Nanoscale visualization and spectral fingerprints of the charge order in ScV6Sn6 distinct from other kagome metals
• Van-Hove annihilation and nematic instability on a Kagome lattice
• Spin-polarized imaging of the antiferromagnetic structure and field-tunable bound states in kagome magnet FeSn
• Colossal orbital Zeeman effect driven by tunable spin-Berry curvature in a kagome metal
• Kagome metals
• Flat optical conductivity in the topological kagome magnet TbMn${}_6$Sn${}_6$
• Electronic band structures of topological kagome materials
• Orbital-selective effect of spin reorientation on the Dirac fermions in a non-charge-ordered kagome ferromagnet Fe${}_3$Ge
• Perspective: imaging atomic step geometry to determine surface terminations of kagome materials and beyond
• Three-dimensional higher-order saddle points induced flat bands in Co-based kagome metals
• Intriguing kagome topological materials
• Quantifying magnetic field driven lattice distortions in kagome metals at the femto-scale using scanning tunneling microscopy
• Competing Lattice Instability and Magnetism on the Surface of Kagome Metals