Doublon-holon binding as origin of Mott transition and fractionalized spin liquid -- Asymptotic solution of the Hubbard model in the limit of large coordination

Sen Zhou, Long Liang, Ziqiang Wang

arXiv:1605.03597May 11, 20161 citation

arXiv:0708.2765 · Journal of Physics and Chemistry of Solids

Doublon–holon binding effects on Mott transitions in two-dimensional Bose Hubbard model

Hisatoshi Yokoyama, Masao Ogata

Published Jun 25, 2008• 5 citations

arXiv HTML PDF

DOI: 10.1016/j.jpcs.2008.06.087

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Doublon-holon binding as origin of Mott transition and fractionalized spin liquid -- Asymptotic solution of the Hubbard model in the limit of large coordination

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An analytical solution of the Mott transition is obtained for the Hubbard model on the Bethe lattice in the large coordination number ( $z$ ) limit. The excitonic binding of doublons (doubly occupied sites) and holons (empty sites) is shown to be the origin of a continuous Mott transition between a metal and an emergent quantum spin liquid insulator. The doublon-holon binding theory enables a different large- $z$ limit and a different phase structure than the dynamical meanfield theory by allowing intersite spinon correlations to lift the $2^N$ -fold degeneracy of the local moments in the insulating phase. We show that the spinons are coupled to doublons/holons by a dissipative compact U(1) gauge field that is in the deconfined phase, stabilizing the spin-charge separated gapless spin liquid Mott insulator.An analytical solution of the Mott transition is obtained for the Hubbard model on the Bethe lattice in the large coordination number ($z$) limit. The excitonic binding of doublons (doubly occupied sites) and holons (empty sites) is shown to be the origin of a continuous Mott transition between a metal and an emergent quantum spin liquid insulator. The doublon-holon binding theory enables a different large-$z$ limit and a different phase structure than the dynamical meanfield theory by allowing intersite spinon correlations to lift the $2^N$-fold degeneracy of the local moments in the insulating phase. We show that the spinons are coupled to doublons/holons by a dissipative compact U(1) gauge field that is in the deconfined phase, stabilizing the spin-charge separated gapless spin liquid Mott insulator.

arXiv:1605.03597May 11, 20161 citation

ξ_{\rm dh}

and the minimum D-D exclusion length

ξ_{\rm dd}

. Generally, a Mott transition occurs when

ξ_{\rm dh}

becomes comparable to

ξ_{\rm dd}

. In the conductive (superfluid) state, domains of D-H pairs overlap with each other (

ξ_{\rm dh}>ξ_{\rm dd}

); thereby D and H can propagate independently as density carriers by successively exchanging the partners. In contrast, intersite repulsive Jastrow (D-D and H-H) factors have little importance for the Mott transition.

{U}_{c1}

, followed by a Mott transition into an electron-fractionalized AF

{}^{*}

phase without coherent excitations at

{U}_{c2}

. Such a phase structure appears to be generic for bipartite lattices without frustration. We show that doublon-holon binding unites the three important ideas of strong correlation: coherent quasiparticles, incoherent Hubbard bands, and deconfined Mott insulator.

An analytical solution of the Mott transition is obtained for the Hubbard model on the Bethe lattice in the large coordination number (

z

) limit. The excitonic binding of doublons (doubly occupied sites) and holons (empty sites) is shown to be the origin of a continuous Mott transition between a metal and an emergent quantum spin liquid insulator. The doublon-holon binding theory enables a different large-

z

limit and a different phase structure than the dynamical meanfield theory by allowing intersite spinon correlations to lift the

2^N

-fold degeneracy of the local moments in the insulating phase. We show that the spinons are coupled to doublons/holons by a dissipative compact U(1) gauge field that is in the deconfined phase, stabilizing the spin-charge separated gapless spin liquid Mott insulator.