Femtosecond optical response of Y-Ba-Cu-O thin films: The dependence on optical frequency, excitation intensity, and electric current
- Laboratory for Laser Energetics and Department of Electrical Engineering, University of Rochester, Rochester, New York 14627 (United States)
We have performed a series of femtosecond reflectivity experiments on various Y-Ba-Cu-O thin films at temperatures ranging from 12 to 300 K. In particular, the dependence of the optical response on probing laser frequency, pumping laser intensity, and bias electric current has been measured. Results obtained at room temperature provide quantitative information on the position of the Fermi level in films with different oxygen content. Systematic analysis of the measurements performed in the superconducting state indicates that the optical response associated with nonequilibrium properties of Y-Ba-Cu-O depends strongly on excitation intensity, sample thickness, and bias current. The results cannot be satisfactorily interpreted as the relaxation dynamics of quasiparticles, and a simple two-fluid model is shown to fail to explain data obtained under low laser excitation. Several tentative explanations are proposed, which provide a more comprehensive understanding of the transient optical response of Y-Ba-Cu-O.
- OSTI ID:
- 5654318
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Vol. 47:21; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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BARIUM OXIDES
SUPERCONDUCTIVITY
CUPRATES
HIGH-TC SUPERCONDUCTORS
YTTRIUM OXIDES
ELECTRIC CURRENTS
FERMI LEVEL
OPTICAL PROPERTIES
PHOTO-INDUCED TRANSIENT SPECTROSCOPY
REFLECTIVITY
STOICHIOMETRY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY LEVELS
FILMS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTROSCOPY
SUPERCONDUCTORS
SURFACE PROPERTIES
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)