Giant magnetostriction in antiperovskite Mn3CuN

Giant magnetostriction of up to 2000 ppm was discovered in the tetragonally distorted ferromagnetic phase of antiperovskite Mn3CuN. This magnetostriction was associated with the rearrangement of thermoelastic martensite variants by the magnetic field, similar to that of Ni2MnGa Heusler alloy. The nitrogen-deficient Mn3CuN0.8 contracts, whereas the stoichiometric Mn3CuN expands, along the field direction. This implies a rotation of the easy axis from the longer a axis in Mn3CuN to the shorter c axis in Mn3CuN0.8. The drastic reduction of the operating magnetic field for magnetostriction in Mn3CuN0.8 suggests a possible supermagnetostriction around the compositional region of direction change in the easy axis.