A variable pole magnet.

The off-stoichiometric antiferromagnetic Heusler alloy FeMnGa decomposes and forms ferromagnetic FeMnGa precipitates embedded in an antiferromagnetic FeMn matrix when temper-annealed at temperatures T  >  550 K. The ferromagnetism of the precipitates is soft so that the magnetization direction of the non-interacting precipitates in a macroscopic material can be manipulated by locally applied fields so that even two similar poles can form at the ends of a centimeter-long bar. The cause for the soft magnetic behavior is due to the weak AF exchange anisotropy of the cubic FeMn matrix and the precipitate.