Bipolaronic charge density waves, polaronic spin density waves and high Tc superconductivity
At large enough electron phonon coupling, the existence of bipolaronic, polaronic and mixed states is rigorously proven for the adiabatic Holstein model at any dimension and any band filling. The ground-state is one of them which then prove the existence of insulating Bipolaronic Charge Density Waves. The role of the quantum lattice fluctuations is analysed and found to be neglegible in that regime but to become essential in case of phonon softening then favoring the occurence of superconductivity. When a strong Hubbard term is also present, the bipolarons break into polorons and the ground state is expected to be a polaronic spin density wave. If the repulsive Hubbard term is comparable to the electron-phonon coupling, the energy for breaking a bipoloron into two polarons can become small and we get instead of these two degenerate structures, a pait of polarons bounded by a spin resonance which we call spin resonant bipolaron''. This resonant bipolaron is still strongly bound, but the role of the quantum lattice fluctuations becomes now very important and yields a sharp broadening of the bandwidth of this resonant bipolarona. Thus, the strong quantum character of these resonant bipolarons could prevent their localization into real space structures which could be insulating bipolaronic CDWs or polaronic SDWS, then favoring the formation of a superconducting coherent state with a possible high {Tc}.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7105313
- Report Number(s):
- LA-UR-92-1844; CONF-9205236--2; ON: DE92017403
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHARGE DENSITY
COUPLING
CRYSTAL MODELS
ELECTRON-PHONON COUPLING
ELECTRONIC STRUCTURE
FLUCTUATIONS
FREQUENCY MIXING
HAMILTONIANS
HIGH-TC SUPERCONDUCTORS
HUBBARD MODEL
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
PHONONS
POLARONS
QUANTUM OPERATORS
QUASI PARTICLES
SPIN WAVES
SUPERCONDUCTORS
VARIATIONS