Kavli Affiliate: Zheng Zhu
| First 5 Authors: , , , ,
| Summary:
Understanding ferromagnetism mechanism in doped Mott insulators on frustrated
lattices remains challenging at intermediate coupling and finite doping. Here,
we study the itinerant ferromagnetism and propose its mechanism in doped Mott
insulators on a geometrically frustrated triangular lattice. Using large-scale
density matrix renormalization group (DMRG) and unrestricted Hartree-Fock
mean-field methods, we reveal that itinerant ferromagnetism appears at
intermediate coupling ($10lesssim Ullinfty$) near 50% electron doping in the
triangular-lattice Hubbard model. By analyzing all microscopic hopping
processes, we find that doublon-singlon exchange alone drives the fully
polarized ferromagnetism and uncovers the particle-hole asymmetry. We also
establish the magnetic phase diagram and compare local spin correlations with
recent experiments. Random phase approximation and DMRG calculations
consistently confirm that the ferromagnetism persists when $SU(2)$ symmetry is
explicitly broken by magnetic anisotropy. These results clarify a microscopic
route to itinerant ferromagnetism at intermediate coupling and finite doping in
doped Mott insulators.
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