paper

Quantum disordered phase near the Mott transition in the staggered-flux Hubbard model on a square lattice

arXiv:1204.3886 · doi:10.1103/PhysRevLett.109.026404

Abstract

We investigate ground state properties of the half-filled staggered-flux Hubbard model on a square lattice. Energy gaps to charge and spin excitations and magnetic as well as dimer orders are calculated as a function of interaction strength by means of constrained-path quantum Monte Carlo method. It is found that the system is a semi-metal at and a Mott insulator with long-range antiferromagnetic order at . In the range , the ground state is an correlated insulator where both magnetic and dimer orders are absent. Furthermore, spin excitation in the intermediate phase appears to be gapless, and the measured spin-spin correlation function exhibits power-law decaying behavior. The data suggest that the non-magnetic ground state is a possible candidate for the putative algebraic spin liquid.

4+ pages, 4 figures, supplemental material

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