The enhanced magnetic properties of Ni nanocrystallites induced by the coupling between Ni/NiO interfaces

Abstract A composite Ni/NiO ultrafine and homogeneous nanocrystallites (NCs) system has been prepared by vacuum thermolysis of coprecipitated product from NiCl 2 and NaOH aqueous solution in the presence of polyvinylpyrrolidone (PVP). It is interesting to note that high magnetic properties have been achieved in this investigated system, including an exchange bias field H E of 180.4 kA/m and a high coercivity H C of 477.9 kA/m at 4.2 K which is one order larger than the bulk Ni or 10 nm pure Ni crystallite systems. These results can be attributed to the antiferromagnetic (AFM) pining effect from AFM NiO to ferromagnetic (FM) Ni.