Magnetic Field Permeability Material: Find Alternative to Faraday Cage

[Pennarin]

I'm a layman so the following terms are not to be taken to the first degree.

I'm searching for a material that offers preferential permeability to magnetic fields. In the article I read (and subsequently lost) the material is offered as an alternative to a Faraday cage in that it doesn't prevent EM fields from entering the cage and the object it protects, but rather encloses the object in a solid shell that forces the fields to flow through the shell - following it's contours - rather than piercing it, for lack of a better term.

Ring a bell, anyone?

 

[Pennarin]

Rechecking...Materials & Chemical Engineering (check).

 

[0xDEADBEEF]

Here you go:
http://en.wikipedia.org/wiki/Mu-metal

 

[Pennarin]

God yes, thank you! With a name like that I understand why I could not find it again with a typical Google search.