Ferrimagnetism of ultracold fermions in a multiband Hubbard system

Lebrat, Martin [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000221236026); Kale, Anant [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000270495630); Kendrick, Lev Haldar [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000181912922); Xu, Muqing [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000323840208); Gang, Youqi [Harvard Univ., Cambridge, MA (United States)] (ORCID:000000031126547X); Nikolaenko, Alexander [Harvard Univ., Cambridge, MA (United States)]; Bonetti, Pietro M. [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000274657043); Sachdev, Subir [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000224327070); Greiner, Markus [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000229352363)

doi:10.1126/science.adq2411

DOE OSTI · 3391473

Ferrimagnetism of ultracold fermions in a multiband Hubbard system

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Abstract

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. Here, 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.

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Lebrat, Martin [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000221236026), Kale, Anant [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000270495630), Kendrick, Lev Haldar [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000181912922), Xu, Muqing [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000323840208), Gang, Youqi [Harvard Univ., Cambridge, MA (United States)] (ORCID:000000031126547X), Nikolaenko, Alexander [Harvard Univ., Cambridge, MA (United States)], Bonetti, Pietro M. [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000274657043), Sachdev, Subir [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000224327070), Greiner, Markus [Harvard Univ., Cambridge, MA (United States)] (ORCID:0000000229352363). 2026-05-07. Ferrimagnetism of ultracold fermions in a multiband Hubbard system. https://doi.org/10.1126/science.adq2411

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