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
(republished on 07/13/06)