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Gapped spin liquid states in a one-dimensional Hubbard model with antiferromagnetic exchange interaction

Jianhui Dai·Xiaoyong Feng·Tao Xiang·Yue Yu
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Abstract

We study the phase diagram of a one-dimensional extended Hubbard model with antiferromagnetic exchange interaction analytically and numerically. The bosonization and transfer-matrix renormalization group methods are used in the corresponding coupling regimes. At half-filling, the system is a Mott insulator with a finite spin excitation gap if the on-site Coulomb repulsion is fairly smaller than the antiferromagnetic exchange J. This Mott-insulator is characterized by the bond-charge-density-wave order or spontaneously dimerization. In the weak-coupling regime where the spin-charge separation holds approximately, the critical point separating the gapless and gapped spin liquid phases is U_c\sim J/2. However, as J increases, the spin-charge couplings become important and the critical point U_c is significantly suppressed and eventually tends to zero as J\to \infty. Away from half-filling, the charge gap completely collapses but the spin gap persists.

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Jianhui Dai, Xiaoyong Feng, Tao Xiang, Yue Yu. 2004-07-06. Gapped spin liquid states in a one-dimensional Hubbard model with antiferromagnetic exchange interaction. https://doi.org/10.1103/physrevb.70.064518

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