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Journal of the Physical Society of Japan

Effect of Localization on a One-Dimensional Half-Filled Extended Hubbard Model

Yoshikazu Suzumura

Published Jun 15, 1985• 7 citations
Publisher

Abstract

By use of the method in the previous paper [J. Phys. Soc. Jpn. 53 (1984) 3918], we study the Anderson localization in a one-dimensional half-filled extended Hubbard model with randomness. A transition from localization into delocalization takes place as the attractive interaction for superconductivity increases. It is shown that the effect of localization on singlet superconductivity (SS) is stronger than that on triplet superconductivity (TS) due to the large quantum fluctuation of TS compared with that of SS.

DOI
10.1143/jpsj.54.2077

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The genuine physical reasons explaining the delocalization effect of the Hubbard repulsion UUU are analyzed. First, it is shown that always when this effect is observed, UUU acts on the background of a macroscopic degeneracy present in a multiband type of system. After this step, I demonstrate that acting in such conditions, by strongly diminishing the double occupancy, UUU spreads out the contributions in the ground state wave function, hence strongly increases the one-particle localization length, and consequently extends the one-particle behavior producing conditions for a delocalization effect. To be valuable, the reported results are presented in exact terms, being based on the first exact ground states deduced at half-filling in two dimensions for a prototype two band system, which is the generic periodic Anderson model at finite value of the interaction.
Abstract We consider Anderson localization in the half-filled Anderson–Hubbard model in the presence of either random on-site interactions or spatially alternating interactions in the lattice. By using dynamical mean field theory with the equation of motion method as an impurity solver, we calculate the arithmetically and geometrically averaged local density of states and derive the equations determining the critical value for the phase transition between metallic, Anderson and Mott insulating phases. The nonmagnetic ground state phase diagrams are constructed numerically. We figure out that the presence of Coulomb disorder drives the system toward the Anderson localized phase that can occur even in the absence of Anderson structural disorder. For the spatially alternating interactions, we find that the metallic region is reduced and the Anderson insulator one is enlarged with increasing interaction modulation. Our obtained results are relevant to current research in ultracold atoms in disordered optical lattices where metal–insulator transition can be observed experimentally by using ultracold atom techniques.