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Theoretical Foucault Images of Superconducting Fluxons

Published online by Cambridge University Press:  02 July 2020

M. Beleggia ,
G. Pozzi ,
K. Harada ,
H. Kasai ,
T. Matsuda ,
T. Yoshida  and
A. Tonomura
M. Beleggia
Affiliation:
Department of Physics and Istituto Nazionale di Fisica per la Materia, viale B. Pichat 6/2, 40127 Bologna, Italy.
G. Pozzi
Affiliation:
Department of Physics and Istituto Nazionale di Fisica per la Materia, viale B. Pichat 6/2, 40127 Bologna, Italy.
K. Harada
Affiliation:
Advanced Research Laboratory, Hitachi Ltd., Hatoyama-machi, Saitama-ken 350-03, Japan.
H. Kasai
Affiliation:
Advanced Research Laboratory, Hitachi Ltd., Hatoyama-machi, Saitama-ken 350-03, Japan.
T. Matsuda
Affiliation:
Advanced Research Laboratory, Hitachi Ltd., Hatoyama-machi, Saitama-ken 350-03, Japan.
T. Yoshida
Affiliation:
Advanced Research Laboratory, Hitachi Ltd., Hatoyama-machi, Saitama-ken 350-03, Japan.
A. Tonomura
Affiliation:
Advanced Research Laboratory, Hitachi Ltd., Hatoyama-machi, Saitama-ken 350-03, Japan.
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Extract

Individual flux lines in superconducting specimens have been recently observed using a 300kV holography electron microscope equipped with a cold field emission gun in the transmission mode by means of the out-of-focus method. In this way it has been possible to observe the dynamic behaviour of fluxons depending upon the variations of the temperature and/or the applied magnetic field or current. The main disadvantage of this method is that correlation with structural defects is troublesome owing to the large defocus distance (of the order of 1 cm for conventional superconductors) necessary for the detection of flux lines.

This drawback is not present in the Foucault technique, where the contrast is generated in the focused image by masking part of the transmitted beam by means of an aperture. Therefore, some preliminary calculations have been made recently using one-dimensional models, which allow for a quick and easy simulation of the factors affecting the experimental conditions .

Type
Recent Developments in Microscopy for Studying Electronic and Magnetic Materials
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 509 - 510
Copyright
Copyright © Microscopy Society of America 1997

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References

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