Axial oxygen-centered lattice instabilities in YBa sub 2 Cu sub 3 O sub 7 : An application of the analysis of extended x-ray-absorption fine structure in anharmonic systems

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.2447· OSTI ID:5071045

Mustre de Leon, J; Conradson, S D; Batistic, I; Bishop, A R; Raistrick, I D; Aronson, M C; Garzon, F H ^[1]

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1. Electronics Research and Theoretical Condensed Matter Physics Groups, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

Analysis of polarized copper {ital K}-edge extended x-ray-absorption fine-structure (EXAFS) measurements on YBa{sub 2}Cu{sub 3}O{sub 7} for temperatures 10{le}{ital T}{sub nom}{le}105 K indicates that the axial oxygen moves in a double-well potential which softens within a fluctuation region associated with the onset of superconductivity in this material. This fluctuation follows from the coupling between the phonons derived from this double-well potential and the superconducting order parameter. The advantages of EXAFS compared to crystallographic measurements in discerning these aspects of the local structure are discussed. Metrical parameters and the characteristics of the potential are determined by curve fits of the EXAFS. This method is based on the calculation of radial distribution functions from selected model potentials, the forms of which are determined along with the absorber-scatterer distance, scatterer type, and number, by optimization of fits of the experimental data with the EXAFS calculated from these parameters. Unlike perturbative treatments, this approach is ideally suited for highly anharmonic systems because the putative potential can be a very close approximation to the real one and it also offers the advantage of providing dynamical information not available through perturbative treatments.

• DOE Contract Number: AC03-82ER13000
• OSTI ID: 5071045
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 45:5; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
FLUCTUATIONS
HIGH-TC SUPERCONDUCTORS
LATTICE VIBRATIONS
ORDER PARAMETERS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
VARIATIONS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES