Ferrimagnetism of ultracold fermions in a multiband Hubbard system
- Martin Lebrat
- Anant Kale
- Lev Haldar Kendrick
- Muqing Xu
- Youqi Gang
- Alexander Nikolaenko
- Pietro M. Bonetti
- Subir Sachdev
- Markus Greiner
2026-05-07
Strongly correlated materials feature multiple electronic orbitals, which are crucial to accurately understanding their many-body properties. In such multiband models, quantum interference can lead to flat energy bands with large degeneracy that gives rise to itinerant magnetic phases. We report on signatures of a ferrimagnetic state realized in a Lieb lattice with ultracold fermions, characterized by antialigned magnetic moments with antiferromagnetic correlations, and concomitant with a finite spin polarization. The signatures remain robust when increasing repulsive interactions from the weakly interacting to the Heisenberg regime and emerge when continuously tuning the lattice unit cell from a square to a Lieb geometry. Our flexible approach paves the way toward exploring exotic phases, such as quantum spin liquids in kagome lattices and heavy fermion behavior in Kondo models.