From BCS-like superconductivity to condensation of local pairs: A numerical study of the attractive Hubbard model

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.54.1286· OSTI ID:285968

Singer, J M ^[1]; Pedersen, M H; Schneider, T ^[2]; Beck, H ^[3]; Matuttis, H ^[4]

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1. Physik-Institut, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland)
2. IBM Research Division, Zurich Research Laboratory, CH-8803 Rueschlikon (Switzerland)
3. Institut de Physique, Universite de Neuchatel, Rue A.L. Breguet 1, CH-2000 Neuchatel (Switzerland)
4. Institut fuer Computeranwendungen I, Universitaet Stuttgart, Pfaffenwaldring 27, D-70569 Stuttgart (Germany)

We investigate the two-dimensional attractive Hubbard model with quantum Monte Carlo techniques to reveal the crossover from a BCS-type superconductivity in the weak-coupling regime to a superconductivity properly described by a Bose-Einstein condensation (BEC) of local, preformed pairs. The crossover from BCS to BEC is particularly well exposed in the temperature dependence of both the spin susceptibility and the double occupancy, as well as by the appearance of a pseudogap in the density of states far above {ital T}{sub {ital c}}. These features are also mirrored in the shape of the specific-heat peak around {ital T}{sub {ital c}}, the separation of the temperature regimes where pair formation and their condensation occur, and in the transfer of spectral weight from the single-particle excitation branch to a pair band in the normal state. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 285968
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 2 Vol. 54; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BCS THEORY
BOSE-EINSTEIN CONDENSATION
ENERGY GAP
ENERGY-LEVEL DENSITY
HUBBARD MODEL
MAGNETIC SUSCEPTIBILITY
MONTE CARLO METHOD
SPECIFIC HEAT
SPECTRAL DENSITY
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TWO-DIMENSIONAL CALCULATIONS