Figure 1

Schematic drawing of the setup used here. A sharp metal tip is attached to a piezoelectric actuator and is used to make electrical contacts to individual, iron filled, carbon nanotubes protruding from the sample.Reuse & Permissions

Figure 2

Sequential TEM images showing the induced movement of iron. A gold tip (on the left, positively biased) is in electrical contact with an iron filled carbon nanotube (on the right): (a) a current of electrons flows from the right to the left (at time $t=0$); (b) the iron core breaks up (at $t=2\min $); (c) iron migrates in the same direction as the electron flow (at $t=3\min $).Reuse & Permissions

Figure 3

Measured thresholds for iron migration: (a) current vs the nanotube outer diameter; and (b) current density (calculated using TEM images) vs the nanotube outer diameter. A threshold in the current density suggests a threshold in the electromigration force. The solid lines are a parabolic fit to the data in (a). (c) Measured resistance, at the electromigration threshold, vs the nanotube diameter. The solid line is a $1/\pi r^2$ fit, indicating a diffusive conduction mechanism.Reuse & Permissions

Figure 4

Sequential TEM images demonstrating the nanopipette action (the transferred iron is indicated by an arrow): (a) schematic drawing of the setup; (b) iron has been migrated to the end of a fixed nanotube; (c) iron is retrieved using a nanotube attached to the movable tip; (d) the nanotube is directed at the side of a large nanotube; (e) the iron is deposited. (f) The iron particle can be retrieved again and (g) it is ready to be deposited elsewhere.Reuse & Permissions