Author(s): Taisei Kitamura, Hiroki Nakai, Hosho Katsura, and Ryotaro Arita We construct a Hubbard model with a nearly flat band whose quantum geometry can be tuned independent of the energy dispersion and the Coulomb interaction. We show that, when the nearly flat band is half filled, the exact ground state of the model exhibits ferromagnetism and that this ferromagnetism … [Phys. Rev. Lett. 137, 126502] Published Tue Sep 15, 2026