Magnetocaloric Effect in Ferromagnetic Ni–Mn Alloys

The magnetization and the magnetocaloric effect have been investigated for Ni–Mn alloys with 66–83 at.%Ni after several heat-treatments. Since the saturation magnetization gradually varies with temperature for 71–83 at.%Ni alloys, the ferromagnetic Curie temperature, TF, is estimated from the magnetocaloric effect. For these alloys, the relative spontaneous magnetization vs. reduced temperature curves almost coincide with each other, satisfying the law of corresponding states: these curves fit the theoretical curve derived from the Brillouin function whose total angular momentum quantum number is an integral multiple of 1/2. Based on the results described above, the strengths of Weiss molecular field at 0 K were calculated for these alloys.