The generalized self-consistent field (GSCF) theory for the one-dimensional repulsive Hubbard model at half-filling is examined in the presence of magnetic field h in wide range of interaction strength U / t . The evolution of the energy gap in the presence of magnetc field describes a magnetic crossover from itinerant magnetism of weakly bound electron-hole pairs with k F =π/2 to the localized magnetic regime, with the Bose condensation of local electron-hole pairs ( k F =0).

Journal of the Physical Society of JapanJan 1, 20020 citations

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J. H. Jefferson

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Journal of Low Temperature Physics

Pairing Phase Diagram of Three Holes in the Generalized Hubbard Model

Oracio Navarro, José Eduardo Espinosa

Published Nov 1, 1999• 0 citations

Publisher

DOI: 10.1023/a:1022501229135

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{\mathit{J}}_{\mathit{c}}

, the phase with paired holes for

{\mathit{J}}_{\mathit{c}}

{\mathit{J}}_{\mathit{s}}

, and the phase separation for J>

{\mathit{J}}_{\mathit{s}}

. Employing for h\ensuremath{\ne}0 the analogy with the universal behavior of one-dimensional interacting fermions within the Luther-Emery regime, we calculate the charge exponent ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$, which can be ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$>1 in the pairing regime, indicating dominant superconducting fluctuations. An analogous analysis, in particular the perturbation expansion in t/h, performed for the Hubbard t-U-h model shows a phase of stable hole pairs for U

{\mathit{U}}_{\mathit{c}}

. Again ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$ seems to approach a nonuniversal value at half-filling.