If by magnetic wire you mean transformer conductors...
Depending on the need I've seen aluminum, copper, or nickel alloys used in transformer windings.
Aluminum is weight and cost saving but takes up more space and is heat sensitive.
Copper dominates small transformers -- we've all seen 'em -- and where specifications are more demanding.
Nickel alloys are used in transformers that have to work while hot, really hot.
Here and there Silver clad Copper has been used. Very pricy.
My dry type transformers use square windings of aluminum.