Observation and Characterization of Ferromagnetic Amorphous Nickel

Annealing an amorphous N${\mathrm{i}}_{80}$ ${\mathrm{B}}_{20}$ alloy results in an intermediate state that is nanocrystalline with N${\mathrm{i}}_3$B crystallites surrounded by an amorphous pure nickel phase. Amorphous nickel is found to be ferromagnetic with saturation magnetization about 60% of that of crystalline nickel and a Curie temperature around 60 K lower. By means of calorimetric measurements, a difference of energy of $0.028\mathrm{eV}{\mathrm{atom}}^{-1\mathrm{}}$ between amorphous and crystalline nickel is reported.