Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 56: Correlated Electrons: Quantum-Critical Phenomena – Theory

TT 56.8: Talk

Wednesday, March 18, 2015, 11:30–11:45, A 053

Phase diagram of the Kane-Mele-Coulomb model — •Martin Hohenadler¹, Francesco Parisen Toldin¹, Fakher F. Assaad¹, and Igor F. Herbut² — ¹Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany — ²Department of Physics, Simon Fraser University, Burnaby, Canada

We determine the phase diagram of the Kane-Mele model with a long-range Coulomb interaction using an exact quantum Monte Carlo method. Long-range interactions are expected to play a role in honeycomb materials because the vanishing density of states in the semimetallic weak-coupling phase suppresses screening. According to our results, the Kane-Mele-Coulomb model supports the same phases as the Kane-Mele-Hubbard model. The nonlocal part of the interaction promotes short-range sublattice charge fluctuations, which compete with antiferromagnetic order driven by the onsite repulsion. Consequently, the critical interaction for the magnetic transition is significantly larger than for the purely local Hubbard repulsion. Our numerical data are consistent with SU(2) Gross-Neveu universality for the semimetal to antiferromagnet transition, and with 3D XY universality for the quantum spin Hall to antiferromagnet transition.

[1] M. Hohenadler, F. Parisen Toldin, I. F. Herbut, and F. F. Assaad,

Phys. Rev. B 90, 085146 (2014)