Quantum non-magnetic state near metal-insulator transition —A possible candidate of spin liquid stateGao-Yong Sun and Su-Peng Kou
Department of Physics, Beijing Normal University - Beijing 100875, China
received 17 June 2009; accepted in final form 8 September 2009; published September 2009
published online 6 October 2009
In this paper, based on the formulation of an O(3) non-linear model, we study the two-dimensional -flux Hubbard model at half-filling. A quantum non-magnetic insulator is explored near the metal-insulator transition that may be a possible candidate of the spin liquid state. Such quantum non-magnetic insulator on square lattice is not induced by frustrations. Instead, it originates from quantum spin fluctuations with relatively small effective spin moments. In the strong-coupling limit, our results of the spin velocity and spin order parameter agree with results obtained from earlier calculations.
71.10.Fd - Lattice fermion models (Hubbard model, etc.).
71.10.Hf - Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems.
75.10.-b - General theory and models of magnetic ordering.
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