We have done a study with small, imperfect Hubbard rings with exact diagonalization. The results for few-electron rings show that the imperfection, whether localized or not, nearly always decreases, but can also increase the persistent current, depending on the character of the imperfection and the on-site interaction. The calculations are generally in agreement with more specialized studies. In most cases the electron spin plays an important role.

arXiv:cond-mat/0310055Physical review. B, Condensed matterNov 4, 200313 citations

AB effect and persistent current in the Hubbard model

Koichi Kusakabe, Hideo Aoki

日本物理学会講演概要集Mar 16, 19950 citations

arXiv:cond-mat/0310556 · Physics Letters A

Strange behavior of persistent currents in small Hubbard rings

Santanu K. Maiti, Jayeeta Chowdhury, Samit Karmakar

Published Oct 21, 2004• 31 citations

arXiv HTML PDF

DOI: 10.1016/j.physleta.2004.10.015

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U

increases, the sign of the current may oscillate depending on the total number of electrons

{N}_{e}

and the hopping

t

between the ring site and the side site. For small hopping

t

, the number of electrons ${N}_{e}^{\ensuremath{'}}$ in the ring sites plays an important role in determining the sign of the current. In contrast to the 1D Hubbard model, a weak or a moderate

U

can strongly enhance the persistent current while the hopping

t

always suppresses the current. The study on the transmittance of the ring with two connected leads indicates that in the large

U

and small

t

case, the transmittance varies with a period $1∕{N}_{e}^{\ensuremath{'}}$ of a flux quantum, demonstrating a spin-charge separation in this system.