Yang, Hong-YuLaeuchli, Andreas M.Mila, FredericSchmidt, Kai Phillip2011-12-162011-12-162011-12-16201010.1103/PhysRevLett.105.267204https://infoscience.epfl.ch/handle/20.500.14299/74819WOS:000286766200010We 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.Flow EquationsNeel OrderExpansiontext::journal::journal article::research article