Orientation-dependent magnetic behavior in aligned nanoparticle arrays constructed by coaxial electrospinning.

A modified electrospinning process has been utilized to align magnetite (Fe(3)O(4)) nanoparticles inside highly oriented poly(ethylene oxide) nanofibers. The structural characterization of the fiber encapsulated nanoparticle arrays via electron microscopy has been detailed, and the magnetic behavior has been studied using vibrating sample magnetometry. The fiber encapsulated nanoparticle arrays exhibit orientation-dependent magnetic behavior with respect to the applied magnetic field. A strong anisotropy along orthogonal axes is obtained for aligned arrays and is manifested as a notable increase in the coercivity and remanence magnetization in the parallel field configuration. The magnetic behavior of isotropic fibers is also examined as a reference and no orientation dependence is observed. The results were found to corroborate theoretical predictions from the chain-of-spheres model. Such hybrid nanoparticle arrays may find relevance in applications requiring an orientation-dependent physical response and in the directional transfer of signals.