We develop a simple statistical mean-field treatment of a disordered Hubbard model. The presence of disorder, reflecting a range of local environments, may lead to local moment formation on an inhomogeneous scale; the essential element of the theory is a self-consistent description of local charges and magnetic moments on sites of different site energies, epsilon, arising from the occurrence of site disorder. The resultant theory is shown to be, in effect, a coupled infinite-component analogue of the single-impurity Anderson model, a helpful physical parallel in interpreting results from the theory. In addition to local charge and moment distributions, we consider self-consistently determined local and total pseudoparticle spectra, epsilon-dependent site occupation probabilities, and a measure of the Fermi-level charge distribution over the sites. Particular attention is given to the evolution of the interplay between disorder and interactions as the band filling fraction, y, is increased from y congruent-to 0 through to the half-filled limit, y = 1, and to the differential influence of the Hubbard U on the local moment stability for different filling fractions.
STATISTICAL MEAN-FIELD APPROACH TO A DISORDERED HUBBARD-MODEL
SIRINGO, Fabio
1993-01-01
Abstract
We develop a simple statistical mean-field treatment of a disordered Hubbard model. The presence of disorder, reflecting a range of local environments, may lead to local moment formation on an inhomogeneous scale; the essential element of the theory is a self-consistent description of local charges and magnetic moments on sites of different site energies, epsilon, arising from the occurrence of site disorder. The resultant theory is shown to be, in effect, a coupled infinite-component analogue of the single-impurity Anderson model, a helpful physical parallel in interpreting results from the theory. In addition to local charge and moment distributions, we consider self-consistently determined local and total pseudoparticle spectra, epsilon-dependent site occupation probabilities, and a measure of the Fermi-level charge distribution over the sites. Particular attention is given to the evolution of the interplay between disorder and interactions as the band filling fraction, y, is increased from y congruent-to 0 through to the half-filled limit, y = 1, and to the differential influence of the Hubbard U on the local moment stability for different filling fractions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
