U. Wieser, U. Kunze, et al.
Physica E: Low-Dimensional Systems and Nanostructures
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 (Formula presented). These features are also mirrored in the shape of the specific-heat peak around (Formula presented), 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.
U. Wieser, U. Kunze, et al.
Physica E: Low-Dimensional Systems and Nanostructures
Frank R. Libsch, Takatoshi Tsujimura
Active Matrix Liquid Crystal Displays Technology and Applications 1997
P. Martensson, R.M. Feenstra
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
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Journal of Physics and Chemistry of Solids