Magnetization Process of h.c.p.-CoIr Nanoparticles with Negative Uniaxial Magnetocrystalline Anisotropy

Superparamagnetic CoIr nanoparticles were proposed as new isotropic magnetic materials that satisfy both high blocking resonance frequency, f_{b ,} and ferromagnetic resonance frequency, f_r. The magnetic material used has negative magnetocrystalline anisotropy. Magnetisation process of the particles were obtained. The phase transition from superparamagnetism to ferromagnetism was also investigated.