A variable pole magnet

Abstract

The off-stoichiometric antiferromagnetic Heusler alloy Fe50Mn45Ga5 decomposes and forms ferromagnetic Fe50Mn25Ga25 precipitates embedded in an antiferromagnetic Fe50Mn50 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 Fe50Mn50 matrix and the precipitate.