← Back to search

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

J. M. Singer, M. H. Pedersen, T. Schneider, H. Beck, H.-G. Matuttis

DOI 10.1103/PhysRevB.54.1286 · Physical Review B

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

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 Tc. These features are also mirrored in the shape of the specific-heat peak around Tc, 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. © 1996 The American Physical Society.

Similar papers