Mott insulating state in a quarter-filled two-orbital Hubbard chain with different bandwidths

Abstract

We investigate the ground-state properties of the one-dimensional two-band Hubbard model with different bandwidths. The density-matrix renormalization group method is applied to calculate the averaged electron occupancies $n$ as a function of the chemical potential $\mu$. Both at quarter and half fillings, "charge plateaux" appear in the $n$-$\mu$ plot, where $d\mu /dn$ diverges and the Mott insulating states are realized. To see how the orbital polarization in the one-quarter charge plateau develops, we apply the second-order perturbation theory from the strong-coupling limit at quarter filling. The resultant Kugel-Khomskii spin-orbital model includes a $magnetic$ field coupled to orbital pseudo-spins. This field originates from the discrepancy between the two bandwidths and leads to a finite orbital pseudo-spin magnetization.

4 pages, 2 figures, Proceedings of LT25

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• Corner Transfer Matrix Renormalization Group Method
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• SU(4) spin-orbit critical state in one dimension
• Magnetization Process of One-Dimensional Quantum Antiferromagnet: The Product Wavefunction Renormalization Group Approach
• Absence of orbital-selective Mott transition in Ca_2-xSr_xRuO4
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Cited by in corpus (3)

• Correlation-induced band suppression in the two-orbital Hubbard model
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• Many-body correlations in one-dimensional optical lattices with alkaline-earth(-like) atoms