Conductivity of CuO[sub 3] chains: Disorder versus electron-phonon coupling

Journal Article · Sun May 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.12230· OSTI ID:5072776

Fehrenbacher, R ^[1]

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1. Theoretische Physik, Eidgenoessische Technische Hochschule Hoenggerberg, CH-8093 Zuerich (Switzerland)

The optical conductivity of the CuO[sub 3] chains, a subsystem of the 1:2:3 materials, is dominated by a broad peak in the midinfrared ([omega][approx]0.2 eV), and a slowly falling high-frequency tail. The one-dimensional (1D) [ital t]-[ital J] model is proposed as the relevant low-energy Hamiltonian describing the intrinsic electronic structure of the CuO[sub 3] chains. However, due to charge-spin decoupling, this model alone cannot reproduce the observed [sigma]([omega]). We consider two additional scattering mechanisms: (i) Disregarding the not so crucial spin degrees of freedom, the inclusion of strong potential disorder yields excellent agreement with experiment, but suffers from the unreasonable value of the disorder strength necessary for the fit. (ii) Moderately strong polaronic electron-phonon coupling to the mode involving Cu(1)-O(4) stretching, can be modeled within a 1D Holstein Hamiltonian of spinless fermions. Using a variational approximation for the phonon Hilbert space, we diagonalize the Hamiltonian exactly on finite lattices. As a result of the experimental hole density [approx]1/2, the chains can exhibit strong charge-density-wave (CDW) correlations, driven by phonon-mediated polaron-polaron interactions. In the vicinity of half filling, charge motion is identified as arising from moving domain walls, i.e., defects in the CDW. Incorporating the effect of vacancy disorder by choosing open boundary conditions, good agreement with the experimental spectra is found. In particular, a high-frequency tail arises as a consequence of the polaron-polaron interactions.

• OSTI ID: 5072776
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 49:17; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HIGH-TC SUPERCONDUCTORS
OPTICAL PROPERTIES
CUPRATES
DOMAIN STRUCTURE
ELECTRON-PHONON COUPLING
ELECTRONIC STRUCTURE
INFRARED RADIATION
POLARONS
VARIATIONAL METHODS
CALCULATION METHODS
COPPER COMPOUNDS
COUPLING
ELECTROMAGNETIC RADIATION
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
QUASI PARTICLES
RADIATIONS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
665411* - Basic Superconductivity Studies- (1992-)