Article
Spin Gap and Superconductivity in Weakly Coupled Ladders: Interladder Oneparticle vs. Twoparticle Crossover
Journal of the Physical Society of Japan (Impact Factor: 1.48). 09/1997; DOI: 10.1143/JPSJ.66.3725
Source: arXiv

Article: Effect of the MediumRange Transfer Energies to the Superconductivity in the TwoChain Hubbard Model
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ABSTRACT: We investigatethe twochain Hubbard model including the next nearestneighbor transfer energies both in the interchain and intrachain directions by use ofthe exactdiagonalization and the variational Monte Carlo methods. We find that superconducting correlation functions are enhanced in such a situation where the density of states of the antibonding band in the neighborhood of the Fermi levelenlarges due to the abovementioned transfer energies, especially, in the situation where the Fermi levelis located a little above the bottom of the antibonding band. In such a situationwe find from the calculated momentum distribution function that this system isin almost oneband situation close to the twoband one. The relevance toladdertype superconductor Sr14xCaxCu24O41 is asserted.Journal of the Physical Society of Japan 05/1999; 68(5):16571663. · 1.48 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study dimensionality effects on the charge gap in the dimerized Hubbard model at quarter filling, with two approaches.First, we examine three chains coupled via the interchain oneparticle hopping integral tb,by the densitymatrix renormalizationgroup (DMRG) method.Next, we consider the d=1+ε dimensional model, using the perturbative renormalizationgroup (PRG) method.The dimensionality is controlled through tb and ε, respectively.Both approaches lead to the conclusion that,for a finite dimerization ratio, the charge gap decreases as the dimensionality increases.Journal of the Physical Society of Japan 07/2000; 69(7):21072112. · 1.48 Impact Factor 
Article: Electronic Properties of the TrellisLattice Hubbard Model: Pseudogap and Superconductivity
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ABSTRACT: We study the electronic states of the twodimensional frustrated coupled ladder (trellis lattice) Hubbard model, which is a theoretical model of the superconducting material Sr14xCaxCu24O41. Temperature dependence of the density of states and magnetic susceptibility are discussed by using the fluctuation exchange method, which is applied to this model for the first time. At half filling, a large pseudogap appears in the density of states at higher temperatures. Moreover, the dwave superconductivity appears at lower temperatures, where the pseudogap is well developed. These behaviors have similarities to the underdoped high Tc cuprates.Physical Review Letters 06/1998; 80(25):56195622. · 7.73 Impact Factor
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