Collective excitations and the crossover from Cooper pairs to composite bosons in the attractive Hubbard model
- 1 March 1992
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 45 (9) , 5087-5090
- https://doi.org/10.1103/physrevb.45.5087
Abstract
Motivated by the short coherence length of the high-temperature superconductors, we study in the negative-U Hubbard model the crossover from Cooper pairs for U≪t to composite bosons for U≫t. We compute the collective-mode spectrum using a generalized random-phase-approximation analysis within the equations-of-motion formalism. We find a smooth evolution of the Anderson mode for weak coupling into the Bogoliubov sound mode for hard-core bosons.Keywords
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