Tuning electronic transport in cobalt-filled carbon nanotubes using magnetic fields

Probing electrical properties of individual carbon nanotubes filled with Fe3C nanowires

The electrical properties of individual multiwall carbon nanotubes (CNTs) filled with Fe₃C nanowires (Fe-CNTs) grown by chemical vapor deposition were investigated. The individual Fe-CNTs were measured by two-probe configuration in a scanning electron microscope, in which one probe was used to contact one end of the nanotubes and the other varied its contact position to measure the resistance along the Fe-CNTs. The data suggest that the ferromagnetic nanowires and the CNTs were well connected into a conduction network, and the resistance of the individual Fe-CNTs decreased as the filling rate increased. Analysis shows that the encapsulated ferromagnetic nanowires played a profound part in determining the electrical behavior of individual Fe-CNTs. The results may be useful for understanding of electronic transport of individual Fe-CNTs and applications based on individual Fe-CNTs.

Fe-functionalized paramagnetic sporopollenin from pollen grains: one-pot synthesis using ionic liquids

The preparation of Fe-decorated sporopollenins was achieved using pollen grains and an ionic liquid as solvent and functionalizing agent. The integrity of the organic capsules was ascertained through scanning electron microscopy studies. The presence of Fe in the capsule was investigated using FT-IR, X-ray photoemission spectroscopy and energy-dispersive X-ray spectroscopy. Electron paramagnetic resonance and magnetization measurements allowed us to demonstrate the paramagnetic behavior of our Fe-functionalized sporopollenin. A few potential applications of pollen-based systems functionalized with magnetic metal ions via ionic liquids are discussed.

Fe3C-filled carbon nanotubes: permanent cylindrical nanomagnets possessing exotic magnetic properties

The present study aims to deduce the confinement effect on the magnetic properties of iron carbide (Fe3C) nanorods filled inside carbon nanotubes (CNTs), and to document any structural phase transitions that can be induced by compressive/tensile stress generated within the nanorod. Enhancement in the magnetic properties of the nanorods is attributed to tensile stress as well as to compression, present in the radial direction and along the nanotube axis, respectively. Finally, the growth of permanent cylindrical nanomagnets has been optimized by applying a field gradient. Besides presenting the growth model of in situ filling, we have also proposed the mechanism of magnetization of the nanotubes. Magnetization along the tube axis has been probed by confirming the pole formation. Fe3C has been selected because of its ease of formation, low TC and incompressibility.