Zero-Field and Field-Induced Interactions between Multicore Magnetic Nanoparticles

Abstract

In this paper, the Langevin dynamics simulation method is used to study magnetic interactions between a pair of multicore magnetic nanoparticles subjected to a uniform magnetic field. Multicore nanoparticles are modelled as spherical rigid clusters of single-domain superparamagnetic cores coupled via dipole-dipole interactions. It is shown that the magnetic force between two well-separated clusters in a strong applied field can be accurately described within the induced point-dipole approximation. However, this approximation also assumes that there are no interactions between clusters in the zero-field limit. On the contrary, simulations indicate the existence of a relatively small attractive magnetic force between clusters, even in the absence of an applied field. It is shown that this force is a direct superparamagnetic analog of the van der Waals interaction between a pair of dielectric spheres.

Heating ability modulation by clustering of magnetic particles for precision therapy and diagnosis

“…The model's features can be discussed along with the ones of recent approaches to the properties of compact particle clusters, based either on numerical solutions of the LLG equation [42,[61][62][63] or Monte-Carlo simulations [43,[64][65][66].…”

From Single-Core Nanoparticles in Ferrofluids to Multi-Core Magnetic Nanocomposites: Assembly Strategies, Structure, and Magnetic Behavior

“…The influence of the van der Waals interaction among MMCs was also investigated (Figure 27d). The magnetic moment is a crucial factor for understanding the spontaneous and magnetically induced clustering of MMCs colloids [272]. Spontaneous or magnetically induced, if the magnetic moment is large enough such that the attraction energy exceeds the thermal energy, MMCs will end up forming clusters whose shape and size depend on the field intensity and field exposure time.…”

Libraries of Uniform Magnetic Multicore Nanoparticles with Tunable Dimensions for Biomedical and Photonic Applications

“…4−7 In the absence of a magnetic field, these materials exhibit the superparamagnetic behavior characteristic of their nanocrystalline composition. 8 When an external magnetic field is applied, however, the individual crystallites collectively magnetize, ultimately forming magnetic domains encompassing the entire cluster. 8−11 It is this combination of superparamagnetism, large magnetic volume, and small dimension that underlies their value as materials for drug delivery, magnetic hyperthermia, magnetic resonance imaging, and responsive photonic crystals.…”

“…Magnetic multicore particles are an important class of nanomaterials whose unique properties are relevant to both medical and optical technologies. − Also referred to as nanoclusters or colloidal nanocrystal clusters, these systems are composed of tens to hundreds of sub-10 nm iron oxide crystallites hardly aggregated into larger, porous clusters. − In the absence of a magnetic field, these materials exhibit the superparamagnetic behavior characteristic of their nanocrystalline composition . When an external magnetic field is applied, however, the individual crystallites collectively magnetize, ultimately forming magnetic domains encompassing the entire cluster. − It is this combination of superparamagnetism, large magnetic volume, and small dimension that underlies their value as materials for drug delivery, magnetic hyperthermia, magnetic resonance imaging, and responsive photonic crystals. ,− …”