In terms of field strength the current best (AFAIK) is NdFeB with small magnets capable of producing strengths on the order of one Tesla. Is there a theoretical upper limit on the field strength of magnetic materials under normal conditions? What might it be? In other words, how much stronger can common magnets get?
Check out the answer to this related question: How to wire a STRONG electromagnet? Note that the saturation of an electromagnetic core is happening because the external field can't do any more to line up the tiny magnetic domains of a given material.. so there's the limit. Idk about specific materials, but for any given material it's limit will be related to the bend on that graph. (once you turn the field off and crystalize domains etc the strength goes back down to whatever)