Off-site Cooper pairing in strong electron-phonon interacting systems

Journal Article · Tue Nov 15 04:00:00 EST 1988 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.342197· OSTI ID:6737698

Lin, D L; Zheng, H

We have developed a new variational treatment to deal with the superconductivity properties of systems with strong electron-phonon interactions by introducing a ''squeeze'' transformation for phonon operators. It is shown that as long as the renormalized intersite electron correlation is attractive, a new type of Cooper pairing occurs whether the renormalized on-site electron correlation is repulsive or atttractive. The transformed electron-phonon interaction gives rise to the squeezed polarons which are, in general, different from the ordinary polarons. We have found from this theory that: (1) the squeezed polaronic state corresponds to a stable minimum of the total energy; (2) the effective mass of the squeezed polaron is much smaller than that of ordinary polarons; (3) both the gap equation and the expression for the critical temperature T/sub c/ in squeezed polaronic states are different from those in ordinary polaronic states as well as from those in BCS theory; and (4) high T/sub c/ is obtained for simple cubic and body centered cubic lattice structures with the electron concentration n = 1.

• Research Organization: Department of Physics and Astronomy, State University of New York at Buffalo, Amherst, New York 14260
• OSTI ID: 6737698
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 64:10; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCC LATTICES
BCS THEORY
COOPER PAIRS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
ELECTRON-PHONON COUPLING
ISOTROPY
LOW TEMPERATURE
MATHEMATICAL OPERATORS
PHONONS
PHYSICAL PROPERTIES
POLARONS
QUANTUM OPERATORS
QUASI PARTICLES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
THREE-DIMENSIONAL CALCULATIONS
TRANSITION TEMPERATURE
VARIATIONAL METHODS