Delocalization effects and charge reorganizations induced by repulsive interactions in strongly disordered chains |
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Authors: | D Weinmann P Schmitteckert RA Jalabert J-L Pichard |
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Institution: | Institut de Physique et Chimie des Matériaux de Strasbourg, 23 rue du Loess, 67037 Strasbourg Cedex, France, FR CEA, Service de Physique de l'état Condensé, Centre d'études de Saclay, 91191 Gif-sur-Yvette Cedex, France, FR
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Abstract: | We study the delocalization effect of a short-range repulsive interaction on the ground state of a finite density of spinless
fermions in strongly disordered one dimensional lattices. The density matrix renormalization group method is used to explore
the charge density and the sensitivity of the ground state energy with respect to the boundary condition (the persistent current)
for a wide range of parameters (carrier density, interaction and disorder). Analytical approaches are developed and allow
to understand some mechanisms and limiting conditions. For weak interaction strength, one has a Fermi glass of Anderson localized
states, while in the opposite limit of strong interaction, one has a correlated array of charges (Mott insulator). In the
two cases, the system is strongly insulating and the ground state energy is essentially invariant under a twist of the boundary
conditions. Reducing the interaction strength from large to intermediate values, the quantum melting of the solid array gives
rise to a more homogeneous distribution of charges, and the ground state energy changes when the boundary conditions are twisted.
In individual chains, this melting occurs by abrupt steps located at sample-dependent values of the interaction where an (avoided)
level crossing between the ground state and the first excitation can be observed. Important charge reorganizations take place
at the avoided crossings and the persistent currents are strongly enhanced around the corresponding interaction value. These
large delocalization effects become smeared and reduced after ensemble averaging. They mainly characterize half filling and
strong disorder, but they persist away of this optimal condition.
Received 5 July 2000 and Received in final form 8 November 2000 |
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Keywords: | PACS 72 15 -v Electronic conduction in metals and alloys – 73 20 Dx Electron states in low-dimensional structures (superlattices quantum well structures and multilayers) – 72 10 Bg General formulation of transport theory – 05 60 Gg Quantum transport |
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