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NdFeB is one of the most popular materials used for making permanent magnets. Yet I could find no link or reference reporting a decent value for the magnetic susceptibility of NdFeB.

Magnetic susceptibilities of some common materials has been listed at the following link: http://en.wikipedia.org/wiki/Magnetic_susceptibility#Examples

A scientific paper or application notes of a good company involved in magnetism would be really helpful.

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I tried adding the tag magnetism. It's automatically being changed to electromagnetism. I wonder what bug this is. –  Shashank Sawant Dec 2 '11 at 20:24
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It's not a bug. The magnetism tag is a declared synonym of electromagnetism because any questions about magnetism should be "filed" under electromagnetism. –  David Z Dec 3 '11 at 0:18
    
Think about why no hard/ferromagnetic materials are included in that list! –  Georg Dec 3 '11 at 1:25
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up vote 1 down vote accepted

Susceptibility in general is the response of an object to an external influence. The magnetic volume susceptibility is defined as:$$ \chi_v = \frac{\partial\mathbf{M}}{\partial\mathbf{H}}$$ So a high susceptibility means you will get a steep response or magnetization $\mathbf{M}$ for a small applied external field $\mathbf{H}$. This definition works nicely for all paramagnetic materials. In ferromagnetic materials and especially in hard ferromagnets like NdFeB you have a large hysteresis. Without any applied field the material shows a finite magnetization and the susceptibility is not well defined (infinite). A more useful parameter to compare different ferromagnetic materials is the relative permeability.

The susceptibility is still used for ferromagnetic materials above their Curie temperature, where you can have large magnetic moments and response to an external field but no magnetization without an external stimulus.

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Could the downvoter please comment what is wrong or improve? –  Alexander Dec 3 '11 at 17:20
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