Modeling stability of trapped ferromagnetic nanoparticle chains

The stability of ferromagnetic nanoparticle chains trapped in nanopores and subjected to external magnetic field is analyzed analytically and numerically in order to study the possibility of directing the assembly of strongly interacting nanoparticles in a two-dimensional array of nanopores. The hysteretic behavior of single-domain particles is described by the Stoner-Wolfharth model and accounted for with a time-stepping technique. The magnitude of the critical magnetic field needed to eject all but one particle from the pore is calculated as a function of field direction, number of particles in the chain, and other parameters showing the practical possibility of assembling a single ferromagnetic particle per surface site.