Magnetic Moment of a Rare-Earth Magnet?

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SUMMARY

The magnetic moment (\mu) of a rare-earth magnet, specifically neodymium, can be approximated using the equation B=\mu_o*2\mu/(4\pi*d^3). For neodymium magnets, which have a permeability close to 1 and produce approximately 1.1T in short-circuit conditions, the magnetic moment can be calculated by multiplying the magnet's volume by 875 kA/m. This approximation is valid for neodymium, while AlNiCo and iron magnets require consideration of their significant permeability, affecting the conversion of short-circuit induction to coercivity.

PREREQUISITES
  • Understanding of magnetic field equations, specifically B=\mu_o*2\mu/(4\pi*d^3)
  • Familiarity with neodymium magnet properties and measurements
  • Knowledge of magnetic permeability and its impact on different magnet types
  • Basic grasp of CGS units, particularly Gauss (G) and Oersted (Oe)
NEXT STEPS
  • Research the properties and applications of neodymium magnets
  • Learn about the magnetic moment calculations for different magnet types
  • Explore the differences in magnetic permeability among AlNiCo, ferrite, and iron magnets
  • Study the implications of magnetic field strength in practical applications
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Physicists, engineers, and materials scientists interested in magnetism, particularly those working with rare-earth magnets and their applications in technology.

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I was trying to find the value of the magnetic field at a distance x from a rare-earth magnet and came across this equation:

B=\mu_o*2\mu/(4\pi*d^3)

Does anyone happen to know the magnetic moment, \mu, of a rare-earth magnet? Nothing specific, an order of magnitude value is fine.

Thank you!
 
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For a neodymium magnet that has permeability near 1 and produces around 1.1T in short-circuit, you could:
multiply its volume by 1.1T/(4pi*10-7)
that is, volume * 875kA/m.

With neodymium, this approximation is not bad. True data there for instance:
http://www.cy-magnetics.com/CY-Mag-NdFeB.pdf
remember 1 G = 100 µT and 1 Oe produces 1 G in vacuum. These were the CGS units.

AlNiCo magnets, as well as iron magnets, have an important permeability, so you can't convert their short-circuit induction to the coercivity as if they were vacuum plus a coil. But with ferrite magnets, the approximation holds more or less.
 

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