|MadSci Network: Engineering|
The strength of a magnetic field such as those generated by electromagnets or permanent magnets is measured by a property called magnetic susceptibility. Permanent magnets are made of ferromagnetic materials, with typical magnetic susceptibilities of 10^3 to 10^5. Most materials are paramagnetic, that is, their internal magnetic fields will tend to line up with an applied external field, increasing the overall field strength. The magnetic susceptibility of paramagnetic materials is small, usually on the order of 10^-5 to 10^-3. "Anti-magnetic" materials do exist, the terminology for these materials is diamagnetic. When an external field is applied to a diamagnetic material, its internal fields will line up against the external field, thus decreasing the overall field strength. However, their susceptibility is also small (and negative), ranging from -10^-5 to -10^-4. So, although the answer to your question is technically YES, the magnetic susceptibility of these materials is millions of times smaller than a typical magnet, so the effect is negligible. There are no known "anti- ferromagnetic" materials. For more information on this topic, check the web pages under the following link:http://maxwell.byu.edu/~spencerr/websumm122/node67.html
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