Magnetostructural Correlations in Nitrogen-Deficient Antiperovskite Mn₃CuN_1-δ

Abstract

Ferromagnetic shape memory effects of antiperovskite Mn 3 CuN are markedly altered by nitrogen deficiency. The martensitic transformation occurs at a lower temperature than ferromagnetic ordering for nitrogen-deficient Mn 3 CuN 0.8 , although they both occur simultaneously for stoichiometric Mn 3 CuN. In the martensitic phase, Mn 3 CuN 0.8 contracts in a direction parallel to the magnetic field, in contrast to the expansion observed in Mn 3 CuN, implying that the easy axis is converted from the longer a axis in Mn 3 CuN to the shorter c axis in Mn 3 CuN 0.8 . The operating magnetic field for magnetostriction drastically decreases for Mn 3 CuN 0.8 , suggesting a possible supermagnetostriction around the critical compositional region for the easy-axis conversion.