Weyl semimetallic, N\'eel, spiral, and vortex states in the Rashba-Hubbard model

Abstract

We investigate the evolution of magnetic phases in the Hubbard model under strong Rashba spin-orbit coupling on a square lattice. By using Lanczos exact diagonalization and determinant quantum Monte Carlo (DQMC) simulations, we explore the emergence of various magnetic alignments as the ratio between the regular hopping amplitude, $t$, and the Rashba hopping term, $t_R$, is varied over a broad range of Hubbard interaction strengths, $U$. In the limit $t_R \rightarrow 0$, the system exhibits N\'eel antiferromagnetic order, while when $t \sim t_R$, a spiral magnetic phase emerges due to the induced anisotropic Dzyaloshinskii-Moriya interaction. For $t_R > t$, we identify the onset of a spin vortex phase. At the extreme limit $t = 0$($t_R \neq 0 $), we perform finite-size scaling analysis in the Weyl semimetal regime to pinpoint the quantum critical point associated with the spin vortex phase, employing sign-free quantum Monte Carlo simulations - the extracted critical exponents are consistent with a Gross-Neveu-type quantum phase transition.