Optical properties of large and small polarons and bipolarons

Journal Article · Sun Oct 31 23:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.13691· OSTI ID:5967472

Emin, D ^[1]

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1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

In systems that are two and three dimensional electronically, a large polaron and a small polaron are distinct types of quasiparticles. The type of polaron formed depends on which electron-lattice interaction is of primary importance. A large polaron forms when the electron-lattice interaction due to the long-range Coulombic interactions between an electronic carrier and a solid's ions are of paramount importance. Competing effects then determine the radius of a large polaron. By contrast, a small polaron can form when a short-range electron-lattice interaction, such as the deformation-potential interaction, is dominant. A small polaron forms as its self-trapped carrier shrinks without limit until it is confined to a single site. Fundamental differences between large and small polarons produce optical spectra with distinguishing features. The absorption due to photoionization of a large polaron depends on products of the matrix elements for exciting a carrier from its self-trapped states to a free-carrier state and the density of these free-carrier states. These matrix elements fall sharply with increasing free-carrier wave vector [ital k] when [ital kR][gt]1, where [ital R] is the large polaron's radius. A large polaron's photoionization produces a temperature-independent absorption band. This band is asymmetric with the absorption intensity on the high-energy side of the peak exceeding that on the low-energy side of the peak.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5967472
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:18; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665400* -- Quantum Physics Aspects of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTRA
COPPER COMPOUNDS
COUPLING
CUPRATES
ELECTRON-PHONON COUPLING
HIGH-TC SUPERCONDUCTORS
IONIZATION
MATRIX ELEMENTS
OPTICAL PROPERTIES
OXYGEN COMPOUNDS
PHOTOIONIZATION
PHYSICAL PROPERTIES
POLARONS
QUASI PARTICLES
SPECTRA
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS