Magnetization Ripple and Arctic Foxes
A model of a polycrystalline magnetic film is considered in which the film is made up of transverse strips of (N) grains, with the magnetization M everywhere parallel within a strip but varying in direction from strip to strip. It is shown that the effective crystalline anisotropy in each strip can...
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Online Access: | http://dx.doi.org/10.1063/1.1714104 https://pubs.aip.org/aip/jap/article-pdf/36/3/1064/10551487/1064_1_online.pdf |
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craippubl:10.1063/1.1714104 2024-02-11T10:01:03+01:00 Magnetization Ripple and Arctic Foxes Callen, H. B. Coren, R. L. Doyle, W. D. 1965 http://dx.doi.org/10.1063/1.1714104 https://pubs.aip.org/aip/jap/article-pdf/36/3/1064/10551487/1064_1_online.pdf en eng AIP Publishing Journal of Applied Physics volume 36, issue 3, page 1064-1066 ISSN 0021-8979 1089-7550 General Physics and Astronomy journal-article 1965 craippubl https://doi.org/10.1063/1.1714104 2024-01-26T09:50:16Z A model of a polycrystalline magnetic film is considered in which the film is made up of transverse strips of (N) grains, with the magnetization M everywhere parallel within a strip but varying in direction from strip to strip. It is shown that the effective crystalline anisotropy in each strip can be represented by a transverse field Ht which varies randomly from strip to strip, where Ht (rms) = K/[2M(2N)½] (K is the crystalline anisotropy constant). It is recalled that random number sequences appear to have a periodicity of about 3.5 units, a phenomenon now recognized as having led to the assignment of a periodicity in the population of arctic foxes. A similar apparent periodicity of the transverse anisotropy field leads to an apparent periodicity of the magnetization ripple. Exchange forces, however, modify the amplitude and wavelength λ of the magnetization ripple when λ<λ0, where λ0=2π (A/Ku)½ is the ``relaxation length'' (A is the exchange constant, Ku is the induced anisotropy constant). When ripple is observed in the electron microscope, an additional instrumental factor must be taken into account. A simple treatment is presented which shows that for grain sizes a<λ0, the angular amplitude of the magnetization ripple θ(rms)≃(πa/λ0)½× {K/[Ku(2N)½]}∼1° and the apparent wavelength λ≃4.6a. Both of these values are in agreement with experiment. When a∼λ0/2π the approximation fails and the linearity between λ and a is destroyed, as observed. Article in Journal/Newspaper Arctic AIP Publishing Arctic Journal of Applied Physics 36 3 1064 1066 |
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Open Polar |
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AIP Publishing |
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craippubl |
language |
English |
topic |
General Physics and Astronomy |
spellingShingle |
General Physics and Astronomy Callen, H. B. Coren, R. L. Doyle, W. D. Magnetization Ripple and Arctic Foxes |
topic_facet |
General Physics and Astronomy |
description |
A model of a polycrystalline magnetic film is considered in which the film is made up of transverse strips of (N) grains, with the magnetization M everywhere parallel within a strip but varying in direction from strip to strip. It is shown that the effective crystalline anisotropy in each strip can be represented by a transverse field Ht which varies randomly from strip to strip, where Ht (rms) = K/[2M(2N)½] (K is the crystalline anisotropy constant). It is recalled that random number sequences appear to have a periodicity of about 3.5 units, a phenomenon now recognized as having led to the assignment of a periodicity in the population of arctic foxes. A similar apparent periodicity of the transverse anisotropy field leads to an apparent periodicity of the magnetization ripple. Exchange forces, however, modify the amplitude and wavelength λ of the magnetization ripple when λ<λ0, where λ0=2π (A/Ku)½ is the ``relaxation length'' (A is the exchange constant, Ku is the induced anisotropy constant). When ripple is observed in the electron microscope, an additional instrumental factor must be taken into account. A simple treatment is presented which shows that for grain sizes a<λ0, the angular amplitude of the magnetization ripple θ(rms)≃(πa/λ0)½× {K/[Ku(2N)½]}∼1° and the apparent wavelength λ≃4.6a. Both of these values are in agreement with experiment. When a∼λ0/2π the approximation fails and the linearity between λ and a is destroyed, as observed. |
format |
Article in Journal/Newspaper |
author |
Callen, H. B. Coren, R. L. Doyle, W. D. |
author_facet |
Callen, H. B. Coren, R. L. Doyle, W. D. |
author_sort |
Callen, H. B. |
title |
Magnetization Ripple and Arctic Foxes |
title_short |
Magnetization Ripple and Arctic Foxes |
title_full |
Magnetization Ripple and Arctic Foxes |
title_fullStr |
Magnetization Ripple and Arctic Foxes |
title_full_unstemmed |
Magnetization Ripple and Arctic Foxes |
title_sort |
magnetization ripple and arctic foxes |
publisher |
AIP Publishing |
publishDate |
1965 |
url |
http://dx.doi.org/10.1063/1.1714104 https://pubs.aip.org/aip/jap/article-pdf/36/3/1064/10551487/1064_1_online.pdf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Journal of Applied Physics volume 36, issue 3, page 1064-1066 ISSN 0021-8979 1089-7550 |
op_doi |
https://doi.org/10.1063/1.1714104 |
container_title |
Journal of Applied Physics |
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36 |
container_issue |
3 |
container_start_page |
1064 |
op_container_end_page |
1066 |
_version_ |
1790596775126499328 |