Magnetic properties of Ni nanoparticles dispersed in silica prepared by high-energy ball milling
Instituto de Ciencia de Materiales de Madrid-CSIC 28049 Cantoblanco, Madrid, Spain
2 Departamento de Física de Materiales, Facultad de Ciencias Físicas Universidad Complutense, Avda. Complutense s/n 28040 Madrid, Spain
Corresponding author: firstname.lastname@example.org
Accepted: 9 February 1998
We analyze the magnetic properties of mechanically ground nanosized Ni particles dispersed in a matrix. Our magnetic characterization of the as-milled samples show the occurrence of two blocking processes and that of non-monotonic milling time evolutions of the magnetic-order temperature, the high-field magnetization and the saturation coercivity. The measured coercivities exhibit giant values and a uniaxial-type temperature dependence. Thermal treatment carried out in the as-prepared samples result in a remarkable coercivity reduction and in an increase of the high-field magnetization. We conclude, on the basis of the consideration of a core (pure Ni) and shell (Ni-Si inhomogeneous alloy) particle structure, that the magnetoelastic anisotropy plays the dominant role in determining the magnetic properties of our particles.
PACS: 75.50.Tt – Fine-particle systems / 75.40.Cx – Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.) / 75.60.Nt – Magnetic annealing and temperature-hysteresis effects
© EDP Sciences, 1998