How strong Rashba spin-orbit coupling reshapes the magnetism of the half-filled square-lattice Hubbard model. Covers the phase diagram in the plane of Rashba-to-regular hopping ratio versus interaction strength: Neel antiferromagnetism when regular hopping dominates, a spiral phase near equal hoppings driven by the induced anisotropic Dzyaloshinskii-Moriya interaction, and a spin vortex phase when Rashba hopping dominates. In the pure-Rashba limit the band structure is a two-dimensional Weyl semimetal, and a sign-free gauge transformation enables quantum Monte Carlo finite-size scaling that locates a Gross-Neveu-type quantum critical point into the vortex phase. Evidence comes from exact diagonalization spin structure factors and correlation-ratio scaling.
The Rashba-Hubbard model describes interacting electrons on a square lattice whose hopping includes a spin-flipping Rashba spin-orbit term alongside regular hopping, and this paper maps its magnetic …