Dispersion-driven ferromagnetism in a flat-band Hubbard system
Dispersion-driven ferromagnetism in a flat-band Hubbard system
We investigate a mechanism to establish ground-state ferromagnetism in flat-band Hubbard systems based on a kind of order-from-disorder effect driven by dispersion. As a paradigm we consider a frustrated diamond chain, where for ideal diamond geometry the lowest one-electron band is flat, but the ground state remains paramagnetic for arbitrary …