3 research outputs found
Ground-state properties of the Falicov-Kimball model with correlated hopping in two dimensions
A new numerical method, recently developed to study ground states of the
Falicov-Kimball model (FKM), is used to examine the effects of correlated
hopping on the ground-state properties of this model in two dimensions. It is
shown that the ground-state phase diagram as well as the picture of
metal-insulator transitions found for the conventional FKM (without correlated
hopping) are strongly changed when the correlated hopping term is added. The
effect of correlated hopping is so strong that it can induce the
insulator-metal transition, even in the strong-coupling limit, where the ground
states of the conventional FKM are insulating for all -electron densities.Comment: 11 pages, 2 figures, LaTe
Formation of charge and spin ordering in strongly correlated electron systems
In this review we present results of our theoretical study of charge and spin
ordering in strongly correlated electron systems obtained within various
generalizations of the Falicov-Kimball model. The primary goal of this study
was to identify crucial interactions that lead to the stabilization of various
types of charge ordering in these systems, like the axial striped ordering,
diagonal striped ordering, phase-separated ordering, phase-segregated ordering,
etc. Among the major interactions that come into account, we have examined the
effect of local Coulomb interaction between localized and itinerant electrons,
long-range and correlated hopping of itinerant electrons, long-range Coulomb
interaction between localized and itinerant electrons, local Coulomb
interaction between itinerant electrons, local Coulomb interaction between
localized electrons, spin-dependent interaction between localized and itinerant
electrons, both for zero and nonzero temperatures, as well as for doped and
undoped systems. Finally, the relevance of resultant solutions for a
description of rare-earth and transition-metal compounds is discussed.Comment: 66 pages, 65 figure
Insulator-to-metal crossover induced by local spin fluctuations in strongly correlated systems
We study the simplified Hubbard (SH) model in the presence of a transverse
field in the infinite dimension limit. The relevant one-particle Green's
functions of the model are obtained by means a perturbative treatment of the
hopping and of the transverse field around the atomic limit. We consider an
analytical solution for the impurity problem. It is shown that this solution is
very accurate in describing the spectral properties of the heavy-particles of
the SH for intermediate and strong values of the on-site Coulomb interaction
. We find that for large values of an insulator-metal transition takes
place as a function of the transverse field. We analyze the metallic phase
through the behavior of the density of states and of the optical conductivity
and static resistivity. Our results for the latter quantity agree with what is
observed in experiments on .Comment: 6 pages, 5 figures, to appear in Journal of Physics: Condensed Matte