M. Hohenadler, F. F. Assaad
We investigate electronic correlation effects on edge states of quantum
spin-Hall insulators within the Kane-Mele-Hubbard model by means of quantum
Monte Carlo simulations. Given the U(1) spin symmetry and time-reversal
invariance, the low-energy theory is the helical Tomanaga-Luttinger model, with
forward scattering only. For weak to intermediate interactions, this model
correctly describes equal-time spin and charge correlations, including their
doping dependence. As apparent from the Drude weight, bulk states become
relevant in the presence of electron-electron interactions, rendering the
forward-scattering model incomplete. Strong correlations give rise to slowly
decaying transverse spin fluctuations, and inelastic spin-flip scattering
strongly modifies the single-particle spectrum, leading to graphene-like edge
state signatures. The helical Tomanaga-Luttinger model is completely valid only
asymptotically in the weak-coupling limit.
View original:
http://arxiv.org/abs/1110.3322
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