Complex electronic topography and magnetotransport in an in-plane ferromagnetic kagome metal

TL;DR

This study investigates the electronic structure and magnetotransport properties of a ferromagnetic kagome metal, revealing Dirac cones, flat bands, and magnetic control of electronic gaps, advancing understanding of topological phases in magnetic materials.

Contribution

It provides the first detailed experimental and theoretical analysis of the electronic topology and magnetotransport in an in-plane ferromagnetic kagome metal, highlighting magnetic control over Dirac gaps.

Findings

Discovery of a Dirac cone near the Fermi energy.

Observation of a flat band from kagome lattice interference.

Magnetic orientation modulates the Dirac gap from 0 to 15 meV.

Abstract

The intricate interplay between flat bands, Dirac cones, and magnetism in kagome materials has recently attracted significant attention from materials scientists, particularly in compounds belonging to the RMn6Sn6 family (R = Sc, Y, rare earths), due to their inherent magnetic frustration. Here, we present a detailed investigation of the ferromagnetic (FM) kagome magnet ScMn6(Sn0.78Ga0.22)6 using angle-resolved photoemission spectroscopy (ARPES), magnetotransport measurements, and density functional theory (DFT) calculations. Our findings reveal a paramagnetic-to-FM transition at 375 K, with the in-plane direction serving as the easy magnetization axis. Notably, ARPES measurements reveal a Dirac cone near the Fermi energy, while the Hall resistivity exhibits a substantial contribution from the anomalous Hall effect. Additionally, we observe a flat band spanning a substantial portion of the Brillouin zone, arising from the destructive interference of wave functions in the Mn kagome lattice. Theoretical calculations reveal that the gap in the Dirac cone can be modulated by altering the orientation of the magnetic moment. An out-of-plane orientation produces a gap of approximately 15 meV, while an in-plane alignment leads to a gapless state, as corroborated by ARPES measurements. This comprehensive analysis provides valuable insights into the electronic structure of magnetic kagome materials and paves the way for exploring novel topological phases in this material class.