Instability of Nagaoka State and Quantum Phase Transition via Kinetic Frustration Control
arXiv:2508.08410 · doi:10.1103/z4gs-c6h6
Abstract
We investigate the Nagaoka-Thouless (NT) ferromagnetic instability in the strongly interacting - Hubbard model by continuously breaking particle-hole symmetry on a tunable square-triangular lattice geometry. We use an analytic approach to show that the fully spin-polarized state becomes unstable to a metastable spin-polaron when the kinetic frustration exceeds a critical, dimension-dependent value. Large-scale density matrix renormalization group simulations reveal a quantum phase transition from the NT ferromagnet to a spiral spin-density wave, which evolves continuously into the Haerter-Shastry antiferromagnet in the large-frustration limit. Remarkably, this transition remains robust at low but finite hole density, making it accessible in cold-atom and moiré Hubbard platforms under strong interactions. A variational analysis further captures the instability mechanism at finite density via frustration-induced magnon band deformation.
13 pages, 8 figures
References in corpus (12)
- A Microscopic Perspective on Moiré Materials
- Frustration- and doping-induced magnetism in a Fermi-Hubbard simulator
- Kinetic Magnetism in Triangular Moiré Materials
- Observation of Nagaoka Polarons in a Fermi-Hubbard Quantum Simulator
- Directly imaging spin polarons in a kinetically frustrated Hubbard system
- Itinerant spin polaron and metallic ferromagnetism in semiconductor moiré superlattices
- The itinerant ferromagnetic phase of the Hubbard model
- Triangular lattice Hubbard model physics at intermediate temperatures
- Nagaoka ferromagnetism in doped Hubbard models in optical lattices
- Pseudogap metal and magnetization plateau from doping moiré Mott insulator
- Finite-Temperature Kinetic Ferromagnetism in the Square Lattice Hubbard Model
- Kinetic magnetism in the crossover between the square and triangular lattice Fermi-Hubbard models