Dynamics and Collective State of Ordered Magnetic Nanoparticles in Mesoporous Systems

In this paper we present a study of superparamagnetic and superspin glass states of magnetic nanoparticles confined in mesoporous templates. Characterization utilizes dynamic magnetization techniques, ac susceptibility, and ferromagnetic resonance, in addition to dc magnetization curves. In order to differentiate between the intrinsic and collective properties, we considered three magnetic nanoparticles systems with comparable size, shape, and crystallinity but with different intrinsic magnetocrystalline anisotropy. Further, confinement effects were studied by considering three different geometries of nanoparticles. The effect of the geometrical confinement and intrinsic anisotropy of the nanoparticles are discussed based on known theoretical predictions