High-[ital T][sub [ital c]] superconductors: Disordered metals with pairing via polarizability from localized states near the mobility edge

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.6492· OSTI ID:6213778

Heeger, A J; Yu, G ^[1]

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1. Institute for Polymers and Organic Solids and Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106 (United States)

The electronic structure of the high-[ital T][sub [ital c]] superconductors is that of a disordered metal with the Fermi energy ([ital E][sub [ital F]]) relatively close to the mobility edge ([ital E][sub [ital c]]); [ital E][sub [ital F]][similar to]0.1--0.2 eV from [ital E][sub [ital c]], lying in the extended-state region in the O 2[ital p] band. In such a metal, the polarizability of the localized states near [ital E][sub [ital c]] can lead to an indirect attractive interaction between electrons (or holes) in extended states near [ital E][sub [ital F]]. Although the direct and exchange terms cancel in second-order perturbation theory, we argue that because of the response of the many-electron wave function to the core hole'' in the intermediate state, exchange processes are turned off near threshold at [ital E][sub [ital F]] in analogy with the x-ray-absorption-edge problem. Thus, [ital V][sub indirect]=[minus]2[ital f][sub [ital L]]([delta]/[ital E][sub [ital F]]) ([ital U][sub [ital L]])[sup 2][vert bar][ital E][sub [ital F]][minus][ital E][sub [ital c]][vert bar][sup [minus]1], where [ital U][sub [ital L]] is the screened Coulomb interaction between electrons in extended states near [ital E][sub [ital F]] and electrons in localized states near [ital E][sub [ital c]], [ital f][sub [ital L]] is the fraction of the total number of states in the band which is localized, and [delta] is an energy interval near [ital E][sub [ital F]] ([delta][lt][ital E][sub [ital F]]) in which the exchange scattering is suppressed. Using [ital V][sub indirect] as the basis for pairing in BCS theory, one obtains 2[Delta][sub 0]=2[vert bar][ital E][sub [ital F]][minus][ital E][sub [ital c]][vert bar]exp [l brace][minus]2/[ital N]([ital E][sub [ital F]])[ital V][sub indirect][r brace], where [ital N]([ital E][sub [ital F]]) is the density of states at [ital E][sub [ital F]].

• OSTI ID: 6213778
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:9; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
ELECTRICAL PROPERTIES
ELECTRONIC STRUCTURE
ENERGY LEVELS
FERMI LEVEL
HIGH-TC SUPERCONDUCTORS
INTERACTIONS
MOBILITY
PAIRING INTERACTIONS
PHYSICAL PROPERTIES
POLARIZABILITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE