Superconducting properties of the attractive Hubbard model in the slave-boson approach

The attractive Hubbard model for normal and superconducting ground states is examined for arbitrary electron concentration by the use of the slave-boson mean-field approximation (SBMFA) technique. This approach, at a saddle-point level, is equivalent to the Gutzwiller approximation. Several superfluid characteristics of the model are shown for hypercubic lattices of all dimensions, including , and a comparison with the Bardeen-Cooper-Schrieffer Hartree-Fock approximation (BCS-HFA) calculations and exact results is made. Our results show quantitative and qualitative corrections of the SBMFA to the HFA. The improvement of the SBMFA over the HFA diminishes with increasing lattice dimensionality. We have also evaluated the energy difference between the superconducting and the normal states; this is compared with available results for the superconducting critical temperatures in various dimensions and Uemura-type plots are obtained. The results confirm and substantiate the assertion of a continuous evolution of the superfluid properties of the model from the weak-coupling (BCS-like) to the strong-coupling (composite-boson superconductivity) limit.

[1]  Y. Uemura.  Bose-Einstein to BCS crossover picture for high-Tc cuprates , 1997 .

[2]  Yung-Li Wang,et al.  MAGNETIC PHASE DIAGRAM OF THE HALF-FILLED THREE-DIMENSIONAL HUBBARD MODEL , 1997 .

[3]  F. Marsiglio.  Evaluation of the BCS Approximation for the Attractive Hubbard Model in One Dimension , 1996, cond-mat/9609275.

[4]  K. Müller,et al.  High-Tc superconductivity 1996 : ten years after the discovery , 1997 .

[5]  W. R. Czart,et al.  Superfluid characteristics of the attractive Hubbard model for various lattice structures , 1996, cond-mat/9701046.

[6]  Robaszkiewicz,et al.  Superconducting properties of the attractive Hubbard model: A slave-boson study. , 1996, Physical review. B, Condensed matter.

[7]  Pistolesi,et al.  Evolution from BCS superconductivity to Bose condensation: Calculation of the zero-temperature phase coherence length. , 1996, Physical review. B, Condensed matter.

[8]  Denteneer.  Strong-coupling expansion for the Hubbard model in arbitrary dimension using slave bosons. , 1996, Physical review. B, Condensed matter.

[9]  Denteneer.  Superfluid density in the two-dimensional attractive Hubbard model: Quantitative estimates. , 1994, Physical review. B, Condensed matter.

[10]  Randeria,et al.  Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations. , 1993, Physical review. B, Condensed matter.

[11]  B. Bułka.  On Antiferromagnetism, Charge Density Wave, and Superconductivity in the Extended Hubbard Model Studied by Means of the Slave‐Boson Method , 1993 .

[12]  Denteneer,et al.  Helicity modulus in the two-dimensional Hubbard model. , 1993, Physical review. B, Condensed matter.

[13]  Kostyrko,et al.  Collective modes of the extended Hubbard model with negative U and arbitrary electron density. , 1992, Physical review. B, Condensed matter.

[14]  R. Frésard,et al.  Unified slave boson representation of spin and charge degrees of freedom for strongly correlated Fermi systems , 1992 .

[15]  Jarrell,et al.  Hubbard model in infinite dimensions: A quantum Monte Carlo study. , 1992, Physical review letters.

[16]  Balseiro,et al.  Slave-boson mean-field theory for the negative-U Hubbard model. , 1992, Physical review. B, Condensed matter.

[17]  Wu,et al.  Basic similarities among cuprate, bismuthate, organic, Chevrel-phase, and heavy-fermion superconductors shown by penetration-depth measurements. , 1991, Physical review letters.

[18]  Vollhardt,et al.  Exact mean-field Hamiltonian for fermionic lattice models in high dimensions. , 1990, Physical review letters.

[19]  R. Micnas,et al.  A Gutzwiller variational scheme for the attractive Hubbard model , 1990 .

[20]  R. Micnas,et al.  Superconductivity in narrow-band systems with local nonretarded attractive interactions , 1990 .

[21]  H. Hasegawa.  Electron correlations in narrow-band systems at finite temperatures: Gutzwiller-type variational approach , 1989 .

[22]  Yang,et al.  Universal correlations between Tc and ns/m (carrier density over effective mass) in high-Tc cuprate superconductors. , 1989, Physical review letters.

[23]  Vollhardt,et al.  Correlated lattice fermions in d= , 1989, Physical review letters.

[24]  Bishop,et al.  Pairing-bag excitations in small-coherence-length superconductors. , 1988, Physical review letters.

[25]  Vollhardt,et al.  Ground-state properties of correlated fermions: Exact analytic results for the Gutzwiller wave function. , 1987, Physical review letters.

[26]  G. Kotliar,et al.  New functional integral approach to strongly correlated Fermi systems: The Gutzwiller approximation as a saddle point. , 1986, Physical review letters.

[27]  R. Micnas,et al.  Hartree theory for the negative- U extended Hubbard model: Ground state , 1981 .

[28]  R. Jelitto.  The density of states of some simple excitations in solids , 1969 .

[29]  Elliott H. Lieb,et al.  Absence of Mott Transition in an Exact Solution of the Short-Range, One-Band Model in One Dimension , 1968 .