Ferromagnetism Mechanism in a Geometrically Frustrated Triangular Lattice

Kavli Affiliate: Zheng Zhu

| First 5 Authors: Qianqian Chen, Shuai A. Chen, Zheng Zhu, ,

| Summary:

We study the emergent itinerant ferromagnetism and propose its underlying
mechanism in the geometrically frustrated triangular lattice. Based on
large-scale density matrix renormalization group simulations and unrestricted
Hartree-Fock mean-field analysis, we identify itinerant ferromagnetic phases in
the intermediate-$U$ Hubbard model with finite doping and reveal the kinetic
mechanisms assisted by geometric frustration. Notably, we find that the
doublon-singlon exchange process among other microscopic charge hoppings solely
drives the fully polarized ferromagnetism for geometrically frustrated
triangular lattice. Additionally, we establish the whole magnetic phase diagram
and illustrate itinerant ferromagnetism within a finite range of electron
doping for finite on-site Coulomb repulsion. The comparison of local spin
correlations with recent cold-atom experiments is also discussed. Our work
enhances the understanding of ferromagnetism mechanisms at intermediate
coupling strength and finite doping concentrations.

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