Published online by Cambridge University Press: 01 February 2011
Closely-spaced ferromagnetic nanoparticles are of interest for applications that include data storage, magnetic imaging and drug delivery. Here, we use off-axis electron holography and micromagnetic simulations to study the magnetic properties of iron nanoparticles encapsulated in three-dimensional arrays of carbon nanotubes. The nanotubes constrain the shapes, sizes and separations of the nanoparticles, as well protecting them from oxidation. We record magnetic induction maps from individual particles that each contain a single magnetic domain. We also discuss the use of electron holography to assess magnetostatic interactions between adjacent particles.