Finite-Temperature Flat-Band Ferromagnetism in the Kagome Hubbard Model
Abstract
Kagome metals exhibit a rich interplay of topology, electronic correlations, and lattice dynamics. Recent discoveries of Kagome materials with a flat band near the Fermi level have revealed a variety of correlated electronic phases. However, elucidating their microscopic origin remains challenging, as realistic descriptions require accounting for multiple orbitals and competing interactions on an equal footing. To disentangle correlation effects from material-specific details and identify the essential physics of the flat-band regime, we study the single-orbital Kagome-Hubbard model at flat-band fillings using dynamical mean-field theory. We find strong signatures of flat-band ferromagnetism, consistent with exact and mean-field ground-state results. Moreover, we uncover an unconventional quasi-ordered phase in which a partially filled spin-polarized flat band pinned at the Fermi level gives rise to persistent local spin fluctuations down to zero temperature, in striking contrast to the classical behavior expected for a conventional ferromagnet. Our results demonstrate that these anomalous fluctuations are an intrinsic consequence of the flat-band degeneracy and establish a minimal framework for understanding correlation effects in flat-band Kagome systems.
Related
- Monolayer van der Waals kagome lattice for high-temperature flat-band physics
- ℤL symmetry breaking in SU(N) Fermi-Hubbard dots at zero and finite temperature
- Coexistence of liquid-like disordered state and weak ferromagnetism in a s = 1 kagome lattice
- Exact SU(N) symmetry resolution of bosonic Hubbard models: general boson-fermion mappings and flat-band singlet-cluster states
- Geometry-Controlled Chern transfer and Flat Band Reconstruction in distorted kagome lattices
BibTeX
@misc{strugatsky2026finitetemperature,
title = {{Finite-Temperature Flat-Band Ferromagnetism in the Kagome Hubbard Model}},
author = {Alon Strugatsky and Jonas B. Profe and Roser Valentí},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09289},
eprint = {2609.09289},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09289},
}
RIS
TY - UNPB
TI - Finite-Temperature Flat-Band Ferromagnetism in the Kagome Hubbard Model
AU - Alon Strugatsky
AU - Jonas B. Profe
AU - Roser Valentí
PY - 2026
DA - 2026/09/13
PB - arXiv
DO - 10.48550/arxiv.2609.09289
UR - https://arxiv.org/abs/2609.09289
AB - Kagome metals exhibit a rich interplay of topology, electronic correlations, and lattice dynamics. Recent discoveries of Kagome materials with a flat band near the Fermi level have revealed a variety of correlated electronic phases. However, elucidating their microscopic origin remains challenging, as realistic descriptions require accounting for multiple orbitals and competing interactions on an equal footing. To disentangle correlation effects from material-specific details and identify the essential physics of the flat-band regime, we study the single-orbital Kagome-Hubbard model at flat-band fillings using dynamical mean-field theory. We find strong signatures of flat-band ferromagnetism, consistent with exact and mean-field ground-state results. Moreover, we uncover an unconventional quasi-ordered phase in which a partially filled spin-polarized flat band pinned at the Fermi level gives rise to persistent local spin fluctuations down to zero temperature, in striking contrast to the classical behavior expected for a conventional ferromagnet. Our results demonstrate that these anomalous fluctuations are an intrinsic consequence of the flat-band degeneracy and establish a minimal framework for understanding correlation effects in flat-band Kagome systems.
ER -