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Vortex fluctuations...
Vortex fluctuations in weak magnetic fields
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Svedlindh, P. (author)
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Festin, O. (author)
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Gunnarsson, K. (author)
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Ronnung, F. (author)
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- Winkler, Dag, 1957 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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(creator_code:org_t)
- 2005
- 2005
- English.
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In: Fluctuation and Noise Letters. - 0219-4775. ; 5:1, s. R1-R12
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https://research.cha...
Abstract
Subject headings
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- Flux-noise and ac susceptibility measurements have been performed on epitaxial films of YBa2Cu3O7. The validity of the fluctuation-dissipation-theorem is verified by the proportionality between flux noise and ac susceptibility results. The nominal zero-field flux-noise spectrum (S-phi (f)) can be characterized as follows: Below a temperature dependent frequency f(0)(T), the flux-noise spectrum is frequency independent. For frequencies f > f(0)(T), the flux-noise spectrum follows f(-x), with x approximate to 1.7 - 1.8. f(0) decreases by 4 orders of magnitude in a temperature interval of Delta T approximate to 0.5 K. Moreover, the flux-noise spectrum scales as fS(phi) = g(f/f(0)(T)), where g((.)) is a scaling function. The influence of weak perturbing magnetic fields was investigated. While the general characteristics of the flux-noise spectrum remain, the characteristic frequency f(0) increases by 3 - 4 orders of magnitude increasing the field from zero to 1 Oe. Flux-noise measurements performed using a compensating field to reduce the residual field in the experimental setup reveal new features of the measured noise spectra. The flux-noise is dominated by thermally generated vortex-antivortex pair fluctuations at temperatures below the mean-field transition temperature, while with decreasing temperature there is a transition to vortex fluctuations being dominated by field generated vortices.
Subject headings
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Keyword
- superconductor
- dynamics
- superconducting films
- transition
- impedance
- vortices
- flux noise
- phase transition
- josephson-junction arrays
- thin-films
- complex
- flux-noise
- motion
- layers
- vortices
Publication and Content Type
- art (subject category)
- ref (subject category)
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