Enhancement of Persistent Currents by the Coulomb Interaction

The persistent current in three-dimensional mesoscopic rings is investigated numerically. The model is tight-binding one with random site-energies and interaction between electrons. The Hartree-Fock approximation is adopted for the interaction between electrons, and models with up to $3\times 4\times 40$ sites are investigated. It is shown that the long-range Coulomb interaction enhances the persistent current considerably for rings with finite width. It is also shown that long-rangedness of the interaction is essential for the enhancement. Screening of the random site-energy is attributed to this enhancement.