Strongest Magnetic Materials: Rare Earths and NdBFe

[magnetics]

As far as I am aware, Rare Earths and particularly NdBFe is the strongest known magnetic material. Is this true and what is the strongest magnetic material known that it is in common use and what is possible theoretically? Thank you.

 

[Gordianus]

As far as I know there's no theoretical limit. The top value in a small volume is something around 30 T and inside an MNR machine is around 2 T.