Microwave transmission and harmonic generation in granular high- T sub c superconducting films: Evidence for viscous flux motion and weak links

Journal Article · Wed May 01 00:00:00 EDT 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.10390· OSTI ID:5622639

Golosovsky, M; Davidov, D; Farber, E ^[1]; Tsach, T; Schieber, M ^[2]

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1. Racah Institute of Physics, Hebrew University of Jerusalem, 91904, Jerusalem, Israel (IL)
2. Xsirius Superconductivity, Israel Division, Kiryat Mada 4, Jerusalem, Israel (IL)

We have studied the microwave transmission {tau} through thin superconducting films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O in the presence of a dc magnetic field {ital H}{sub 0} and an alternating magnetic field, {ital H}{sub 1} cos2{pi}{ital f}{sub 0}{ital t}. The alternating field generates many harmonics due to the nonlinear response of the complex resistivity. The microwave transmission with {bold H}{sub 0} in the plane of the film depends on the orientation {ital cphi} of {bold H}{sub 0} with respect to the microwave electric field. We found experimentally that the field-dependent part of the transmission behaves like {delta}{tau}{sub {ital f}}{proportional to}{vert bar}{ital H}{sub 0} sin{ital cphi}{vert bar}. This indicates a macroscopic Lorentz force and strongly suggests that the complex resistivity in the magnetic field is dominated by a viscous-flux-motion dissipation mechanism. We demonstrate a simple model for the harmonic generation based on viscous fluxon motion. A comparison of the experiment with the model allows an estimate of the viscosity coefficient {eta} for the fluxons in the direction of the {ital c} axis to be {eta}=(2--4){times}10{sup {minus}9} cgs units for Y-Ba-Cu-O film at {ital T}=70 K. Theoretical models suggest that the magnitude of {eta} is appropriate to weakly pinned Abrikosov fluxons. The dc transport properties of superconducting films containing internal Josephson junctions are strongly affected by microwave irradiation and serve, therefore, as a diagnostic tool to detect the presence of weak links.'' Higher-order harmonics can be generated in all types of studied films independent of the presence or absence of weak links. However, in the presence of weak links, the onset temperature for the harmonic generation {ital T}{sub {ital c}}{sup {prime}} is lower than the onset temperature for the change in the microwave transmission, {ital T}{sub {ital c}}.

• OSTI ID: 5622639
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 43:13; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
PHOTON TRANSPORT
BISMUTH OXIDES
CALCIUM OXIDES
COPPER OXIDES
STRONTIUM OXIDES
YTTRIUM OXIDES
ENERGY LOSSES
HARMONIC GENERATION
HIGH-TC SUPERCONDUCTORS
MAGNETIC FIELDS
MICROWAVE RADIATION
SUPERCONDUCTING FILMS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTROMAGNETIC RADIATION
FILMS
FREQUENCY MIXING
LOSSES
NEUTRAL-PARTICLE TRANSPORT
OXIDES
OXYGEN COMPOUNDS
RADIATION TRANSPORT
RADIATIONS
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties