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Prog. Theor. Phys. Vol. 102 No. 5 (1999) pp. 953-963

[ Full Text PDF : FREE ACCESS (175K) ]

Gutzwiller-Type Projected BCS Ground States for Attractive Hubbard Model in Infinite Dimensions

Yasuo Y. Suzuki,1,*) Shin-ichi Saito2 and Susumu Kurihara2

1NTT Basic Research Laboratories, Atsugi 243-0198, Japan
2Department of Physics, Waseda University, Tokyo 169-8555, Japan

(Received July 19, 1999)

Abstract:

In order to develop our theoretical understanding of the superconducting state of strongly correlated electron systems, we investigate the many-body ground state of the attractive Hubbard model in infinite dimensions using the Gutzwiller-type projected BCS variational (GBCS) wave function. We first calculate various physical quantities by numerically evaluating analytical equations for systems in the thermodynamic limit. We then show that the GBCS wave function has the lowest energy when the gap parameter has a mixture of s wave and extended s wave pairing symmetry and that the ground state energy of the GBCS is lower than that of either the BCS or Fermi liquid at any electron density and any strength of the attractive interactions in our model. We also show that with infinite strength interactions, each pair of electrons with opposite spins forms a tightly bound pair on a lattice site (BEC-like state). We find a smooth crossover from a BCS-like state with large, overlapping Cooper pairs (for weakly attractive interactions) to a BEC-like state of composite bosons formed out of the tightly bound pairs of fermions (for strongly attractive interactions).


URL : http://ptp.ipap.jp/link?PTP/102/953/
DOI : 10.1143/PTP.102.953


*)E-mail: suzuki@brl.ntt.co.jp

[ Full Text PDF : FREE ACCESS (175K) ] Citation:

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Citing Article(s) :

  1. Journal of the Physical Society of Japan 70 (2001) pp. 1186-1189 :
    Is Evolution from Weak to Strong Coupling Superconductivity Always Continuous?
    Shin-ichi Saito, Hiroyuki Yoshimoto, Yasuo Y. Suzuki and Susumu Kurihara
  2. Journal of the Physical Society of Japan 79 (2010) 064401 (6 pages) :
    Polarized Superfluidity in the Imbalanced Attractive Hubbard Model
    Akihisa Koga and Philipp Werner
  3. Journal of the Physical Society of Japan 81 (2012) 063002 (4 pages) :
    Low-Temperature Properties of the Fermionic Mixtures with Mass Imbalance in Optical Lattice
    Nayuta Takemori and Akihisa Koga
  4. Journal of the Physical Society of Japan 81 (2012) 064718 (14 pages) :
    Variational Monte Carlo Study of Spin-Gapped Normal State and BCS–BEC Crossover in Two-Dimensional Attractive Hubbard Model
    Shun Tamura and Hisatoshi Yokoyama
  5. Progress of Theoretical Physics Vol. 107 No. 4 (2002) pp. 637-654 :
    Random Wandering around Homoclinic-Like Manifolds in a Symplectic Map Chain
    Shin-itiro Goto, Kazuhiro Nozaki and Hiroyasu Yamada

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