Anomalous magnetic behavior in Ni-Ag nanoparticles

Ni fine particles are synthesized by a simple chemical reduction method. The particles obtained are strain-free and have spherical shape so that shape anisotropy is negligible. X-ray diffraction was used to study crystalline structure and the lattice parameters. It is concluded that the nanoparticles are an assembly of non-interacting particles whose moments get blocked with decreasing temperatures. A comparative study of air-annealed Ni (Ni_air) and silver-coated Ni (Ni_Ag) samples with different concentration provide a clear evidence of strong interparticle interactions for the samples prepared with higher molar concentration.