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Magnetic Contrast in the cFEG SEM Using the Upper (Above-the-Lens) Detector

Published online by Cambridge University Press:  02 July 2020

L.N. Brewer  and
V.P. Dravid
L.N. Brewer
Affiliation:
Department of Materials Science and Engineering, Northwestern University 2225 North Campus Drive, Evanston, IL, 60208
V.P. Dravid
Affiliation:
Department of Materials Science and Engineering, Northwestern University 2225 North Campus Drive, Evanston, IL, 60208
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Extract

An unconventional and important use of the SEM is in the study of magnetic phenomena of materials. Many magnetic phenomena occur on the surfaces of materials as is the case for magnetic recording in computer memory and audio tapes. The “above-the-lens” or “upper” detector of the cFEG SEM(Hitachi S4500) is especially suited to probing surface phenomena (Fig. 1). The upper detector is used in combination with a magnetic “snorkel” lens which pulls secondary electrons (SE) up to the detector, resulting in an extremely high and pure SE yield. While magnetic imaging in a standard, side-mounted Everhart-Thornley (lower) detector is well understood, the image contrast mechanism for the upper detector is not presently known. We tested both energy filtering and trajectory contrast as possible magnetic contrast mechanisms using a cassette recording tape (Fe2O3 based) and barium hexaferrite ceramic magnets.

Two sets of experiments were performed to explore the magnetic contrast.

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. 523 - 524
Copyright
Copyright © Microscopy Society of America 1997

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References

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