Electron-screening effects on the self-trapping of polarons

Journal Article · Wed May 01 04:00:00 EDT 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.53.13497· OSTI ID:284362

Iadonisi, G ^[1]; Capone, G ^[2]; Cataudella, V; De Filippis, G ^[1]

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1. Dipartimento di Scienze Fisiche, Universita di Napoli, I-80125 Napoli (Italy)
2. Department of Physics, Antwerpen University, Antwerpen B-2610 (Belgium)

In a polar semiconductor with a number of electrons or holes in the conduction or valence band, the interactions of an external charge with the longitudinal optical phonon are screened by the electron/hole density. Consequently the self-energy depends on the density. We show that, for any value of the Fr{umlt o}hlich electron-phonon coupling constant {alpha}, an electronic density {ital n}{sup {asterisk}} can be found such that for density {ital n}{approx_gt}{ital n}{sup {asterisk}} the Lee polaron theory for the intermediate coupling (not self-trapped polarons) gives self-energies lower than those of the strong coupling (self-trapped polarons). This is due to the static and dynamical screening introduced by the plasmon field on the electron-phonon interaction. This result is confirmed by applying the path-integral technique to the problem and calculating both the self-energy and the renormalized mass. It is found that the density {ital n}{sup {asterisk}} depends on {alpha} and {eta} (the ratio of the high frequency dielectric constant to the static one). We note that typical charge carrier densities in high {ital T}{sub {ital c}} superconductors are larger than {ital n}{sup {asterisk}} for a wide range of value of {alpha}. This indicates that no self-trapped polarons might have a role in high {ital T}{sub {ital c}} superconductors. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 284362
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 20 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CHARGE RENORMALIZATION
EFFECTIVE MASS
ELECTRON-PHONON COUPLING
HIGH-TC SUPERCONDUCTORS
PLASMONS
POLARONS
SELF-ENERGY
SEMICONDUCTOR MATERIALS