Unrestricted slave-boson mean-field approximation for the two-dimensional Hubbard model

Slave - boson mean - field theory of spin - and orbital - ordered states in the degenerate Hubbard model ∗

The mean-field theory with the use of the slave-boson functional method is generalized to take account of the spinand orbital-ordered state in the doubly degenerate Hubbard model. Some numerical calculations are presented of the antiferromagnetic orbital-ordered state in the half-filled simple-cubic model. The orbital order in the present theory is much reduced compared with that in the Hartree...

Beyond extended dynamical mean-field theory: Dual boson approach to the two-dimensional extended Hubbard model

Dimensional crossover in Sr2RuO4 within slave-boson mean-field theory

Motivated by the anomalous temperature dependence of the c-axis resistivity of Sr2RuO4, the dimensional crossover from a network of perpendicular one-dimensional chains to a two-dimensional system due to a weak hybridization between the perpendicular chains is studied. The corresponding two-orbital Hubbard model is treated within a slave-boson mean-field theory (SBMFT) to take correlation effec...

Helicity Modulus and Effective Hopping in the Two-dimensional Hubbard Model Using Slave-boson Methods

The slave-boson mean-field method is used to study the two-dimensional Hubbard model. A magnetic phase diagram allowing for paramagnetism, weakand strong ferromagnetism and antiferromagnetism is constructed and compared to the corresponding phase diagram using the Hartree-Fock approximation (HFA). Magnetically ordered regions are reduced by a factor of awi ıbout 3 along both the t/U and density...

Boson-fermion Model beyond Mean-field Approximation

A model of hybridized bosons and fermions is studied beyond the mean field approximation. The divergent boson self-energy at zero temperature makes the Cooper pairing of fermions impossible. The frequency and momentum dependence of the self-energy and the condensation temperature T c of initially localized bosons are calculated analytically. The value of the boson condensation temperature T c i...