Effect of dipolar and exchange interactions on magnetic blocking of maghemite nanoparticles

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

“…The estimation of the latter, in the case of dendroncapped clusters, falls in the range that predicts a blocking process associated with intermediate strength dipolar interactions (0.05 < ψ < 0.13) and not to a spin glass state that would have been expected for values in the range 0.005 < ψ < 0.05 [125]. In the dendron-based system, the superparamagnetic behavior likely originates from nanoclusters incorporating a larger average distance among their constituent nanocrystals.…”

Comparison of surface effects in SiO2 coated and uncoated nickel ferrite nanoparticles

“…The lesser dipolar interactions are also evident by a continuous increase of FC curve of coated nanoparticles (see Fig. 4(a)) below the respective blocking temperature [31]. Silica matrix acts as a spacer among the nanoparticles which reduces both the interparticle interactions and agglomeration.…”

Highly crystalline superparamagnetic iron oxide nanoparticles (SPION) in a silica matrix

“…A recent paper by Han 37.8 emu/g, and coercivities of 810 Oe and 1180 Oe, respectively [67]. Nadeem et al prepared ultrafine maghemite nanoparticles with size of about 4 nm, high coercivity of 3008 Oe and low saturation magnetization [68]. These magnetic properties arise both from the atoms which reside on the surface of the nanoparticles, and from the finite number of atoms in the nanoparticle crystalline core.…”

“…These magnetic properties arise both from the atoms which reside on the surface of the nanoparticles, and from the finite number of atoms in the nanoparticle crystalline core. It has been shown that particle size, morphology, defects, core-shell and dipolar interactions have a large influence on the magnetic properties of the samples [1,56,62,63,65,[67][68][69][70][71][72][73][74]. Moreover, the finite size and surface effects are usually masked by the presence of particle size distribution and by a magnetic interaction between the particles, and it is very difficult to distinguish the real contribution of finite size and surface effects on the magnetic properties.…”