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Q & A: Electrical insulators conducting magnetic fields

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Most recent answer: 10/22/2007
Q:
Is there any material which can not conduct electricity but can conduct magnetic flux?
- Mike (age 48)
Metuchen , NJ USA
A:
We're guessing that by 'conduct magnetic flux' you mean gather in the flux lines from some external source, like typical ferromagnetic materials do. Since a lot a familiar materials that magnetize are metals, like iron (after which 'ferromagnetism' is named) it's easy to get the impression that all ferromagnetic materials are metals which conduct electricity fairly well.

Actually, there are also many ferromagnetic materials which are insulators. One way to find some is to go to a search engine and type in 'ferromagnetic insulator'. One example is magnetic garnet minerals. Some iron oxides are also ferromagnetic insulators. In some manganite perovskite materials, slight variations in composition, pressure, and temperature can lead to almost non-magnetic poorly conducting states, ferromagnetic poorly conducting states, ferromagnetic metals, antiferromagnetic insulators, etc.
There are also ferromagnetic materials which act like insulators on a large scale because their magnetic metal parts are surrounded by insulators, including rubber or insulating ceramics.

Mike and Tom

(published on 10/22/2007)

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