Evolution of magnetic nanophases of Ni embedded in Al2O3 (0Â 0Â 1) matrix by X-ray magnetic circular dichroism

► An unique XAS/XMCD experiment of embedded nanoparticles in insulating/dielectric oxide matrix to distinguish magnetic contributions of different phases. ► Element-specific magnetic characterizations of Ni nanoparticles dispersed in sapphire (Al2O3-0 0 1) matrix prepared by ion-implantation (Ni:5 × 1016-2 × 1017 ions cm−2) has been investigated. ► We study the systematic evolutions of magnetic phases of Ni nanoparticles as a function of different Ni fluences and their magnetic response in the presence of other NiOx phases. ► Our XMCD data provide a distinct 'fingerprint' for the complex magnetic interactions between the nanophases of Ni NPs and NiOx.