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Effect of Hund's rule coupling on SU(4) spin-orbital system

Hiroaki Onishi, Takashi Hotta

cond-mat.str-elarXiv:cond-mat/0607104

Abstract

We investigate the ground-state property of a one-dimensional two-orbital Hubbard model at quarter filling by numerical techniques such as the density-matrix renormalization group method and the exact diagonalization. When the Hund's rule coupling J is zero, the model is SU(4) symmetric. In fact, both spin and orbital correlations have a peak at q=π/2, indicating an SU(4) singlet state with a four-site periodicity. On the other hand, with increasing J, it is found that the peak position of the orbital correlation changes to q=π, while that of the spin correlation remains at q=π/2. We briefly discuss how the SU(4) symmetry is broken by J.

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