Remanence

Remanence is the magnetization left behind in a medium after an external magnetic field is removed. It is denoted in equations as $M\_r$. In engineering applications it is often assumed that the magnetization "M" is synonymous with the residual flux density "B" (they differ by a factor of $mu\_0$, $B\_R=mu\_0\; M$) hence the remanence is frequently denoted as $B\_R$ (see the image).

The remanence magnitude can be taken from a hysteresis loop at the intersections of the loop with the vertical magnetization axis. It can be measured with a B-H Analyzer.

Remanence has application in:
* geology (concerning paleomagnetism)
* computer engineering (concerning data storage and recovery, see data remanence)
* physics (concerning magnetism).

The value of remanence is one of the most important parameters characterising permanent magnets. Neodymium magnets, for example, have a remanence approximately equal to 1.3 teslas.

References

*R. V. Lapshin, [http://www.nanoworld.org/homepages/lapshin/publications.htm#analytical1995 “Analytical model for the approximation of hysteresis loop and its application to the scanning tunneling microscope”] , Review of Scientific Instruments, volume 66, number 9, pages 4718-4730, 1995.

External links

* [http://hyperphysics.phy-astr.gsu.edu/hbase/solids/magperm.html Coercivity and Remanence in Permanent Magnets]
* [http://www.coolmagnetman.com/ Magnet Man]

See also

*retentivity
*Coercivity
*hysteresis