Editing Barnett effect

{{Short description|Magnetization of an uncharged body when spun on its axis}}
The '''Barnett effect''' is the [[magnetization]] of an uncharged body when spun on its axis.<ref name="Blaine">{{cite book |title=The Cold Universe |author=Bruce T. Draine |editor1=Andrew W. Blain |editor2=F. Combes |editor3=Bruce T. Draine |editor4=D. Pfenniger |editor5=Yves Revaz |page=276 |chapter-url=https://books.google.com/books?id=A6ceYPsxsSEC&pg=PA276 |isbn=3-540-40838-X |year=2003 |chapter=§7.3 Barnett effect |publisher=Springer}}</ref> It was discovered by American physicist [[Samuel Jackson Barnett|Samuel Barnett]] in 1915.<ref>{{cite journal
  | last = Barnett  | first = S. J.
  | title = Magnetization by Rotation
  | year = 1915
  | journal = [[Physical Review]]
  | volume = 6  | issue = 4  | pages = 239–270
  | doi =  10.1103/PhysRev.6.239
|bibcode = 1915PhRv....6..239B }}</ref>

An uncharged object rotating with angular velocity {{math|''ω''}} tends to spontaneously magnetize, with a magnetization given by
: <math>M = \chi \omega / \gamma, </math>
where {{math|''γ''}} is the [[gyromagnetic ratio]] for the material, {{math|''χ''}} is the [[magnetic susceptibility]].

The magnetization occurs parallel to the axis of spin. Barnett was motivated by a prediction by [[Owen Richardson]] in 1908, later named the [[Einstein–de Haas effect]], that magnetizing a ferromagnet can induce a mechanical rotation. He instead looked for the opposite effect, that is, that spinning a ferromagnet could change its magnetization. He established the effect with a long series of experiments between 1908 and 1915.

== See also ==
* [[London moment]]

==References==
{{reflist}}

==Further reading==
* {{cite journal |url=https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.7.129 |author=S. J. Barnett |title=Gyromagnetic and Electron-Inertia Effects |journal=Reviews of Modern Physics |volume=7 |issue=2 |pages=129–166 |year=1935 |doi=10.1103/RevModPhys.7.129|bibcode=1935RvMP....7..129B |url-access=subscription }}

[[Category:Magnetism]]


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