Tunable flat band on the surface of a rhombohedral kagome ferromagnet
Abstract
A central goal in the exploration of kagome-based materials is the realization of a flat band that has meV bandwidth and lies close to the Fermi energy. The prevailing assumption is that band flattening originates from destructive hopping processes on the kagome lattice. We perform scanning tunneling microscopy (STM) on the layered kagome ferromagnet Fe3Sn2 and show that it indeed hosts a flat band near the Fermi energy, which is manifested as a sharp peak in the differential tunneling conductance. First-principles slab calculations reveal, however, that this band is flattened not by the destructive interference of intralayer hopping, but by interlayer hopping between rhombohedral-stacked kagome planes in Fe3Sn2, and is confined to the surface layer. This surface band, forming in the vicinity of the Brillouin zone corners K̅ and K'̅, exhibits rich magnetic-field dependence, including fine structure due to valley-symmetry breaking by rotated Fe moments, as well as a persistent diamagnetic shift associated with orbital magnetic moments, all reproduced by our calculations. Our results, highlighting the crucial role of layer stacking on the band structure of kagome magnets, demonstrate experimentally an alternative mechanism of generating magnetically tunable flat bands in atomically thin volumes of topological magnets.
Related
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BibTeX
@misc{que2026tunable,
title = {{Tunable flat band on the surface of a rhombohedral kagome ferromagnet}},
author = {Xinglu Que and Qingyu He and Lihui Zhou and Lilian Prodan and Vladimir Tsurkan and István Kézsmárki and Hidenori Takagi and Dennis Huang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.19857},
eprint = {2609.19857},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.19857},
}
RIS
TY - UNPB
TI - Tunable flat band on the surface of a rhombohedral kagome ferromagnet
AU - Xinglu Que
AU - Qingyu He
AU - Lihui Zhou
AU - Lilian Prodan
AU - Vladimir Tsurkan
AU - István Kézsmárki
AU - Hidenori Takagi
AU - Dennis Huang
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.19857
UR - https://arxiv.org/abs/2609.19857
AB - A central goal in the exploration of kagome-based materials is the realization of a flat band that has meV bandwidth and lies close to the Fermi energy. The prevailing assumption is that band flattening originates from destructive hopping processes on the kagome lattice. We perform scanning tunneling microscopy (STM) on the layered kagome ferromagnet Fe_3Sn_2 and show that it indeed hosts a flat band near the Fermi energy, which is manifested as a sharp peak in the differential tunneling conductance. First-principles slab calculations reveal, however, that this band is flattened not by the destructive interference of intralayer hopping, but by interlayer hopping between rhombohedral-stacked kagome planes in Fe_3Sn_2, and is confined to the surface layer. This surface band, forming in the vicinity of the Brillouin zone corners K̅ and K'̅, exhibits rich magnetic-field dependence, including fine structure due to valley-symmetry breaking by rotated Fe moments, as well as a persistent diamagnetic shift associated with orbital magnetic moments, all reproduced by our calculations. Our results, highlighting the crucial role of layer stacking on the band structure of kagome magnets, demonstrate experimentally an alternative mechanism of generating magnetically tunable flat bands in atomically thin volumes of topological magnets.
ER -