Effective spin model for the spin-liquid phase of the Hubbard model on the triangular lattice |
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Authors: | Yang Hong-Yu L?uchli Andreas M Mila Frédéric Schmidt Kai Phillip |
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Affiliation: | Lehrstuhl für Theoretische Physik I, TU Dortmund, Dortmund, Germany. |
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Abstract: | We show that the spin-liquid phase of the half-filled Hubbard model on the triangular lattice can be described by a pure spin model. This is based on a high-order strong coupling expansion (up to order 12) using perturbative continuous unitary transformations. The resulting spin model is consistent with a transition from three-sublattice long-range magnetic order to an insulating spin-liquid phase, and with a jump of the double occupancy at the transition. Exact diagonalizations of both models show that the effective spin model is quantitatively accurate well into the spin-liquid phase, and a comparison with the Gutzwiller projected Fermi sea suggests a gapless spectrum and a spinon Fermi surface. |
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