Photogeneration of self-localized polarons in YTBa/sub 2/ Cu/sub 3/O/sub 7/-delta and La/sub 2/ CuO/sub 4/. Technical report

Technical Report · Mon Aug 01 00:00:00 EDT 1988

OSTI ID:6617217

Kim, Y H; Foster, C M; Heeger, A J; Cox, S; Acedo, L

Photoinduced infrared absorption measurements of YBa/sub 2/Cu/sub 3/O/sub 7/-delta (delta=0.75) and La/sub 2/CuO/sub 4/ are reported. The authors observed photoinduced infrared active vibrational modes and associated phonon bleachings which indicate the formation of a localized structural distortion in the Cu-O plane around the photogenerated carriers. In both materials, an associated electronic transition indicates that this structural distortion causes the formation of a self-localized electronic state in the energy gap. The photoinduced distortion and the associated self-localized gap state demonstrate that the photoexcitations are relatively long-lived polarons (or bipolarons). The dynamic mass associated with the distortion is smaller in YBa/sub 2/Cu/sub 3/O/sub 7/-delta than in La/sub 2/CuO/sub 4/ (smaller dynamic mass implies a longer range distortion). Since these features are not observed in the isostructural compound, La/sub 2/NiO/sub 4/, we suggest that polaron (or bipolaron) formation may play an important role in the high temperature superconductivity.

• Research Organization: California Univ., Santa Barbara (USA). Dept. of Chemistry
• OSTI ID: 6617217
• Report Number(s): AD-A-199209/8/XAB; TR-25
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CUPRATES
DOCUMENT TYPES
DYNAMICS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HIGH TEMPERATURE
LANTHANUM COMPOUNDS
MASS
MECHANICS
OXIDES
OXYGEN COMPOUNDS
PHONONS
PHYSICAL PROPERTIES
POLARONS
PROGRESS REPORT
QUASI PARTICLES
RARE EARTH COMPOUNDS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS