Charge-transfer polarons and excitons

Journal Article · Wed May 01 04:00:00 EDT 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.11474· OSTI ID:5661917

Lorenzana, J ^[1]; Yu, L ^[2]

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1. International School for Advanced Studies, Strada Costiera 11, 34014 Trieste, Italy (IT)
2. International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste, Italy (IT)

We show that polarons and excitons of charge-transfer origin arise quite naturally in the {ital p}-{ital d} model of high-temperature superconductors. We consider the limit in which on-site Coulomb repulsion on both Cu and O is taken to be infinite and treat the Cu-O repulsion {ital U}{sub {ital p}{ital d}} in the Hartree-Fock approximation. We find that the uniform Hartree-Fock solution is unstable (the compressibility is negative) for small enough doping. Using an unrestricted Hartree-Fock scheme we find in one dimension (1D) that one particle added to the half-filled case forms a self-trapped polaron state of charge-transfer origin. We also find that there is no phase separation. Within the same formalism we subsequently study exciton states. In 2D we obtain similar compressibility results, suggesting that the ground state is also polaronic. Our results are also relevant for one-dimensional charge-transfer systems.

• OSTI ID: 5661917
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:13; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHALCOGENIDES
CHARGE EXCHANGE
COPPER COMPOUNDS
COPPER OXIDES
EXCITONS
HARTREE-FOCK METHOD
HIGH-TC SUPERCONDUCTORS
ONE-DIMENSIONAL CALCULATIONS
OXIDES
OXYGEN COMPOUNDS
POLARONS
QUASI PARTICLES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
TWO-DIMENSIONAL CALCULATIONS