skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations

Abstract

We study the evolution of the ground state and the excitation spectrum of the two- and three-dimensional attractive (negative-{ital U}) Hubbard model as the system evolves from a Cooper-pair regime for {ital U}{much_lt}{ital t}, to a composite boson regime for {ital U}{much_gt}{ital t}. Our work is motivated by the observation that the high-temperature superconductors, with their short coherence lengths and unusual normal-state properties, may be in an intermediate coupling regime between these two limits. A mean-field analysis of pairing, suitably generalized to account for a shift in the chemical potential, is known to be able to describe the ground-state crossover as a function of {ital U}/{ital 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. We then include a long-range Coulomb interaction and show that it leads to a plasmon which again evolves smoothly from weak to strong coupling.

Authors:
 [1];  [2]
  1. Department of Physics, State University of New York, Stony Brook, New York 11794-3800 (United States)
  2. Argonne National Laboratory, MSD 223, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)
Publication Date:
Research Org.:
Argonne National Laboratory (ANL), Argonne, IL
OSTI Identifier:
142611
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 49; Journal Issue: 10; Other Information: PBD: 1 Mar 1994
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; SUPERCONDUCTIVITY; HUBBARD MODEL; COLLECTIVE EXCITATIONS; GROUND STATES; COOPER PAIRS; RANDOM PHASE APPROXIMATION; EQUATIONS OF MOTION; BOSONS; COULOMB CORRECTION

Citation Formats

Belkhir, L., and Randeria, M.. Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations. United States: N. p., 1994. Web. doi:10.1103/PhysRevB.49.6829.
Belkhir, L., & Randeria, M.. Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations. United States. doi:10.1103/PhysRevB.49.6829.
Belkhir, L., and Randeria, M.. Tue . "Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations". United States. doi:10.1103/PhysRevB.49.6829.
@article{osti_142611,
title = {Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations},
author = {Belkhir, L. and Randeria, M.},
abstractNote = {We study the evolution of the ground state and the excitation spectrum of the two- and three-dimensional attractive (negative-{ital U}) Hubbard model as the system evolves from a Cooper-pair regime for {ital U}{much_lt}{ital t}, to a composite boson regime for {ital U}{much_gt}{ital t}. Our work is motivated by the observation that the high-temperature superconductors, with their short coherence lengths and unusual normal-state properties, may be in an intermediate coupling regime between these two limits. A mean-field analysis of pairing, suitably generalized to account for a shift in the chemical potential, is known to be able to describe the ground-state crossover as a function of {ital U}/{ital 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. We then include a long-range Coulomb interaction and show that it leads to a plasmon which again evolves smoothly from weak to strong coupling.},
doi = {10.1103/PhysRevB.49.6829},
journal = {Physical Review, B: Condensed Matter},
number = 10,
volume = 49,
place = {United States},
year = {1994},
month = {3}
}