Magnetic properties of ultrafine‐grained cobalt samples obtained from consolidated nanopowders

Abstract

Co powders having nominal average particle size of 50 and 240 nm were synthesized using a polyol method and then consolidated by hot isostatic pressing (HIP) or the emerging spark plasma sintering (SPS) compaction processes. Bulk polycrystalline aggregates were obtained, having average grain sizes of about 200 and 300 nm, respectively. It is found that both nanoparticles and consolidated samples exhibit a soft ferromagnetic behavior. The magnetization reversal likely occurs by nucleation/propagation process. However, a curling process can be involved in the magnetization reversal for the smaller particles. The dynamic measurements provide for the consolidated samples magnetic parameters corresponding to bulk cobalt with vanishing anisotropy. The contribution of the intergranular region is found to be negligible. We can infer that the used consolidation routes insure a good magnetic interfacial contact between the particles.

Magnetic and magneto-optical properties of assembly of nanodots obtained from solid-state dewetting of ultrathin cobalt layer

“…Geometrical parameters (size, shape) and magnetic anisotropy are known to govern the reversal process. Thus, the coercive field H c for nanoparticles strongly depends on size and shape [5,[27][28][29][30][31]. As a general trend, H c is found to increase up to a maximum and then to decrease to zero with decreasing the nanoparticle size.…”

Morphological and magnetic study of plasma assisted solid-state dewetting of ultra-thin cobalt films on conductive titanium silicon nitride supports

“…Indeed, both equilibrium and nonequilibrium magnetic properties of cobalt NPs, depend on geometrical parameters such as particle size and shape. Consequently, the coercive field value Hc of the NPs is size and shape dependent [1][2][3][4][5]. MNPs can be disposed on a substrate and integrated in electronic and photonic devices fabrications [6,7], bio-sensing [8], catalysis [9], and data storage applications [10,11].…”