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Flux pinning - Wikipedia

Flux pinning - Wikipedia

This service is more advanced with JavaScript available, learn more at http://activatejavascript.org Zeitschrift für Physik B Condensed MatterJune 1979, Volume 32, Issue 2, pp 175–187 | Cite asThe fluctuations of the flux-tube nucleation frequencyν* in the current-induced resistive state have been studied using a strictly passive micro-fieldprobe as a flux-tube counter. The measurements were performed with constricted indium films near 2.0K. They included both the bandwidth of the rf signal from the field probe and the temporal variations ofν*. From a comparison of the power spectrum of the noise voltage and of the functionν*(t) the relative importance of the fluctuations in the size and in the nucleation frequency of the flux tubes can be evaluated. In addition to fluctuations ofv* around an average value, switching between two frequenciesν1* andν2* can be observed. As a function of sample voltage the bandwidth shows oscillations which appear to be associated with the change in the time-averaged number of flux tubes traveling simultaneously through the constricted film. Narrow-band flux nucleation withΔν*/ν*<10−1 is observed only in rather restricted regimes of the sample voltage.Supported by a grant from the Deutsche ForschungsgemeinschaftUnable to display preview. Download preview PDF.Unable to display preview. Download preview PDF.Over 10 million scientific documents at your fingertips© 2017 Springer International Publishing AG. Part of Springer Nature. Not logged in Not affiliated 178.62.106.94



Associate ProfessorB.S., Stanford University (1981)Ph.D., University of Chicago (1986)The main focus of our research is in the area of superconductivity, with a particular interest in the static and dynamic properties of superconducting vortices and other magnetic flux structures. We use the technique of scanning Hall probe microscopy to image the vortices, allowing direct spatial information about their static configurations and dynamic flow patterns.Recently, we have developed high-speed techniques to detect in real time the passage of individual flux tubes (containing ~100 flux quanta) beneath a fixed Hall sensor. Using this technique, we have measured for the first time clear evidence for the chaotic dynamics of driven flux bundles in a superconductor.We are also working on the control of vortex motion at the single-vortex level. Using advanced lithographic techniques, we are preparing novel surface-modulated superconductors that will allow us to move vortices in controlled single steps. Such structures may find novel applications in precision metrology.More information on Prof. Field’s research is available on his research website.© 2017 College of Natural Sciences Colorado State University - All Rights Reserved





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