arXiv:cond-mat/9806180 · Physical review. B, Condensed matter

Multiorbital Hubbard model in infinite dimensions: Quantum Monte Carlo calculation

Jong E. Han, Mark Jarrell, Daniel Lee Cox

Published Aug 15, 1998• 90 citations

Abstract

Using the quantum Monte Carlo technique we compute thermodynamics and spectra for the orbitally degenerate Hubbard model in infinite spatial dimensions. With increasing orbital degeneracy we find in the one-particle spectra broader Hubbard bands (consistent with increased kinetic energy), a narrowing Mott gap, and increasing quasiparticle spectral weight. Hund's rule exchange coupling decreases the critical on-site Coulomb energy for the Mott transition. The metallic regime resistivity for twofold degeneracy is quadratic in temperature at low temperatures.

DOI: 10.1103/physrevb.58.r4199

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arXiv:cond-mat/9806180 · Physical review. B, Condensed matter

Multiorbital Hubbard model in infinite dimensions: Quantum Monte Carlo calculation

Jong E. Han, Mark Jarrell, Daniel Lee Cox

Published Aug 15, 1998• 90 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physrevb.58.r4199

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{U}_{c1}

and

{U}_{c2}

as well as the critical temperature

{T}_{c}

depend on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations play a key role to control the Mott transitions in the multiorbital Hubbard model.

U

, and the charge-transfer energy

Δ

between the

d

- and

p

-orbitals, transfer integrals

t_{pd}

t_{pp}

t_{dd}

between

p

d

p

p

and

d

d

sites respectively. The critical behaviour of the quasiparticle weight is also obtained analytically.

ν=1/2

, which is consistent with the scaling arguments. Increasing level split between two orbitals drives crossover from the Mott insulator with high spin state to the band insulator with low spin state, where the spin gap amplitude increases and becomes closer to the charge gap. Experimental relevance of our results especially to Haldane materials is discussed.