Journal Article

<i>In situ</i> observations of domain structures and magnetic flux distributions in Mn-Zn and Ni-Zn ferrites by Lorentz microscopy and electron holography

Takehiro Kasahara, Daisuke Shindo, Hideyuki Yoshikawa, Takafumi Sato and Koichi Kondo

in Microscopy

Published on behalf of The Japanese Society of Microscopy

Volume 56, issue 1, pages 7-16
ISSN: 2050-5698
Published online January 2007 | e-ISSN: 2050-5701 | DOI: http://dx.doi.org/10.1093/jmicro/dfl042
In situ observations of domain structures and magnetic flux distributions in Mn-Zn and Ni-Zn ferrites by Lorentz microscopy and electron holography

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Domain structures and magnetic flux distributions in Mn-Zn and Ni-Zn ferrites are investigated by in situ observations with Lorentz microscopy and electron holography. In situ Lorentz microscopic observation with the magnetic field applied reveals that the domain walls in Mn-Zn ferrite move easily across the grain boundary. On the other hand, each grain of Ni-Zn ferrite is magnetized by domain wall motion inside the grain. By taking a series of holograms with adjustment of the optical axis and astigmatism while the magnetic field is applied, we succeeded in observing the change in magnetic flux distribution quantitatively. Eventually, it is clarified that magnetization rotation does not take place in the magnetization process of Ni-Zn ferrite. The domain wall widths δ in Mn-Zn and Ni-Zn ferrites are evaluated to be 73 and 58 nm, respectively. Furthermore, through direct observation of the domain structure in Ni-Cu-Zn ferrite with Lorentz microscopy, it is found that the grains with size below 1.5 μm diameter are single domain.

Keywords: electron holography; domain wall motion; magnetic flux; ferrite; Lorentz microscopy; in situ observation

Journal Article.  3898 words.  Illustrated.

Subjects: Biological Sciences

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