Soft Magnetic Properties in Nano-scale Inhomogeneous Ni₃Mn Alloys

抄録

We have observed superparamagnetic behaviors and giant magnetoresistance in Ni₃Mn alloy annealed at 673 and 693 K for several periods. The coercive force is small of 0.14∼0.44 kA·m⁻¹ in these inhomogeneous alloys. The average size of the ferromagnetic cluster increases from ∼2.8 to ∼10 nm with long-range ordering. The saturation magnetization also increases with a volume fraction, ε, in the ordered regions and reaches to 0.92 T at ε∼80% where the alloy is ferromagnetic. These results suggest that the present Ni₃Mn alloys are magnetically soft due to the nanocrystalline morphology: ordered ferromagnetic domains with nanometer in size are distributed in a disordered nonmagnetic matrix.