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Martin Hohenadler, Thomas Lang, Fakher Assaad
We consider a quantum spin hall insulator as realized by the Kane-Mele model with spin orbit coupling λ supplemented by a Hubbard U term. On the basis of projective auxiliary field quantum Monte Carlo simulations on lattice sizes up to 12 × 12, we map out the magnetic phase diagram. Beyond a critical value of U > Uc the quantum spin Hall insulating state is unstable towards magnetic ordering. At U < Uc we study the spin, charge and single particle dynamics of the helical edge state by retaining the Hubbard interactions only on the edge of a ribbon. As Uc is approached we observe a substantial depletion of low-lying spectral weight in the dynamical charge structure factor, and a robust signature of the helical edge state in the single particle spectral function. |
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