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Effet des corrélations électroniques et du spin sur les courants permanents dans les anneaux unidimensionnels désordonnés

Abstract : We study the combined effect of disorder and interaction on the persistent current in one-dimensional rings with strongly correlated electrons within the Hubbard-Anderson hamiltonian. The DMRG algorithm is used to compute the many-body ground-state energies for periodic and antiperiodic boundary conditions in order to obtain the stiffness which is a measure for the persistent current. For moderate values of the interaction, we find an increase of the stiffness when the disorder is non zero whatever the filling is for an even number of electrons. This is qualitatively different from the behaviour of spinless fermions, confirming the spin effect in the increase of the persistent current. A study of the localization length at half-filling confirms the existence of this increase and allows to extrapolate towards bigger systems. In the strong interaction limit, the stiffness decreases while the interaction increases. Two different power laws are found characterizing this decrease at and away from half-filling. Only at half-filling, the disorder increases the persistent current at strong interaction. The effect is consistent with the behavior of the localization length. An analytical approach is developed in the strong interaction limit to confirm the features found numerically. The kinetic energy term is treated as a perturbation and leads to corrections to the many-body ground-state energies and the phase sensitivity. An expansion in the disorder strength permits to deduce the disorder dependance of the phase sensitivity. At half-filling, this confirms that persistent currents are enhanced by the disorder.
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https://tel.archives-ouvertes.fr/tel-00007446
Contributor : Elise Gambetti <>
Submitted on : Thursday, November 18, 2004 - 4:46:59 PM
Last modification on : Thursday, April 23, 2020 - 2:26:22 PM
Long-term archiving on: : Friday, April 2, 2010 - 10:41:58 PM

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  • HAL Id : tel-00007446, version 1

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Elise Gambetti. Effet des corrélations électroniques et du spin sur les courants permanents dans les anneaux unidimensionnels désordonnés. Matière Condensée [cond-mat]. Université Louis Pasteur - Strasbourg I, 2004. Français. ⟨tel-00007446⟩

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