The 44.7Cuhyphen;20.6Mnhyphen;34.7Al (at.thinsp;percnt;) alloy, which exhibits a very high coercive force after aging at 300thinsp;deg;C, has been found to show a displaced hysteresis loop when it is cooled to 77 K in a magnetic field. The hysteresis loop of the sample which aged for more than 60 min at 300thinsp;deg;C is shifted along the magnetization axis instead of along the field axis. The magnetization measured at 300 K for a maximum applied field of 15 kOe becomes larger than that at 77 K after aging for 45 min at 300thinsp;deg;C. In the magnetization versus temperature curves of the sample aged for more than 45 min at 300thinsp;deg;C, the magnetization decreases monotonically with decreasing temperature. The increase of coercive force, which is obtained in the sample aged for more than 45 min at 300thinsp;deg;C, corresponds to the increase of the displacement of the hysteresis loop. These magnetic behaviors are considered to be caused by the exchange anisotropy interaction between the regions of ferromagnetic Heusler or Mnhyphen;poor phase and ferrimagnetic or antiferromagnetic Mnhyphen;rich phase.
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