Magnetic trapping of nanometer- and micrometer-sized particles

Nanometer- and micrometer-sized particles (NPs and MPs) of gas-phase Co, Fe, and Fe–Nd–Dy–B were magnetically trapped on a substrate. For the magnetic trapping of NPs, two stepwise evolutions were investigated: (1) the formation of NP aggregates above a critical diameter of 8nm and (2) increase in the length to a few micrometers, which is the result of the equilibrium between the magnetostatic and thermal energies of NPs and the granular linear chains such as granular nanorods and nanofibers. The magnetic trapping of MPs or MPs∕NPs is particularly interesting because of the sequential pearl-necklace-like growth and magnetic separation in the linear chains.