Structural and magnetic properties of sputter deposited cobalt–silica nanocomposite thin films

The present study was focused to investigate the effect of Co concentration on structural and, magnetic properties of Co–SiO2 nanocomposite thin films. Co–SiO2 nanocomposite films with different cobalt atomic concentration up to 49 at% were synthesized using direct current (DC) and radiofrequency (RF) magnetron co-sputtering. TEM and XRD analyses reveal the formation of both FCC (1 1 1) and HCP (1 0 1) phases in all the samples. The particle size and surface roughness of these films is found to increase with increase in cobalt concentration. Magnetic measurements reveal that the embedded cobalt nanoparticles behave as superparamagnets when their size is ≤16 nm. The coercivity at 3 K decreases while value of blocking temperature increases with increase in the size of embedded Co nanoparticles.