Disorder and Interactions in the Hubbard Model
We investigate the single-band repulsive Hubbard model with random site energies as a model for the disordered electron system in the strong-interaction limit. Previous scaling treatments of this problem, pioneered by Finkel’shtein, are based on a perturbative treatment of the interactions and the scaling eventually fails as the couplings become large. We treat the disordered Hubbard model at large repulsion U by a mean-field slave-boson technique coupled with the matrix nonlinear sigma model method to average over the disorder. In first approximation, we find an effective hamiltonian with an attractive coupling inversely proportional to U. A new feature is an enhancement of band narrowing due to the interplay of correlation and disorder. The scaling drives 1/U to weak coupling consistent with the apparent scaling of U to strong coupling in the conventional approach, to which our method is complementary. We find that the conductivity decreases monotonically as the temperature decreases, a new result.
KeywordsHubbard Model Fermi Liquid Effective Bandwidth Charge Susceptibility Slave Boson
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