Exchange Anisotropy and Long-Range Magnetic Order in the Mixed Intermetallic Compounds, (Mn, Fe)3Sn

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Abstract
Magnetization and neutron diffraction results are reported for hexagonal (DO19) pseudo‐binary compounds of compositions intermediate between antiferromagnetic Mn3Sn and ferromagnetic Fe3Sn. Both Mn2.5Fe0.5Sn and Mn2FeSn exhibit a complex magnetization‐field‐temperature behavior that is suggestive of a finely mixed ferro‐antiferromagnetic state of the type previously proposed for Cu–Mn and other disordered alloys. This exchange anisotropy state is further demonstrated by displaced hysteresis loops produced by cooling to low temperatures in a magnetic field; unidirectional anisotropies of about 106 erg/g are computed from these loops. However, unlike Cu–Mn, these compounds also give neutron diffraction evidence for some long‐range periodic magnetic order. The magnetic structure for Mn2.5Fe0.5Sn is basically that for Mn2Sn, in which three equivalent sublattice moments add vectorially to zero by describing a closed equilateral triangle, whereas Mn2FeSn probably has a ferrimagnetic variant of this structure.