Exchange Anisotropy in Disordered Ni3Mn

Magnetic hysteresis loop and torque measurements were made on a disordered polycrystalline ${\mathrm{Ni}}_3\mathrm{Mn}$ specimen which had been cooled to liquid helium temperatures in a magnetic field. The hysteresis loop measured parallel to this field was shifted from its symmetrical position about the origin. The torque curves indicated a single direction (rather than axis) of easy magnetization and revealed a rotational hysteresis which continued to increase up to the highest field of measurement (8000 oe). It is concluded that the coexistence of ferromagnetism and antiferromagnetism at low temperatures in these alloys, as previoulsy reported, gives rise to exchange anisotropy interactions of the type conceived by Meiklejohn and Bean for the ferromagnetic Co‐antiferromagnetic $\mathrm{CoO}$ system. However, important differences in detail between disordered ${\mathrm{Ni}}_3\mathrm{Mn}$ and the $\mathrm{Co}‐\mathrm{CoO}$ system are suggested by the experimental results.