Tailoring of Magnetic Properties of NiO/Ni Composite Particles Fabricated by Pulsed Laser Irradiation

We present NiO/Ni composite particles with face-centered cubic (fcc) structure prepared by a pulsed laser irradiation of NiO nanoparticles dispersed in liquid. The sizes of particles and the Ni content in NiO/Ni composites were controlled by tuning the laser parameters, such as laser fluence and irradiation time. We found that the weight fraction of Ni has a significant impact on magnetic properties of composite particles. Large exchange bias (H(EB)) and coercivity field (H(C)) were observed at 5 K due to the creation of heterojunctions at interfaces of ferromagnetic Ni and antiferromagnetic NiO. For the NiO/Ni composites with 80% of NiO we have observed the largest values of exchange bias (175 Oe) and coercive field (950 Oe), but the increase of Ni weight fraction resulted in the decrease of both H(C) and H(EB) values.