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arXiv · 1204.3886

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

Chia-Chen Chang·Richard T. Scalettar
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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 $U/t$ by means of constrained-path quantum Monte Carlo method. It is found that the system is a semi-metal at $U/t\lesssim 5.6$ and a Mott insulator with long-range antiferromagnetic order at $U/t \gtrsim 6.6$. In the range $5.6\lesssim U/t\lesssim 6.6$, 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.

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Chia-Chen Chang, Richard T. Scalettar. 2012-04-17. Quantum disordered phase near the Mott transition in the staggered-flux Hubbard model on a square lattice. https://doi.org/10.1103/physrevlett.109.026404

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