Tuning the magnetic properties of iron-filled carbon nanotubes

We tuned the magnetic properties of iron-filled multi-walled carbon nanotubes (Fe@CNTs) by careful manipulation of the synthesis parameters in a two zone furnace. Due to the small dimensions of iron filling in these samples they have some of the highest values of magnetization saturation reported for Fe@CNTs. Magnetic characterization of the Fe@CNTs revealed that their coercivity can be systematically tuned by varying the pyrolysis temperature, whereas the saturation magnetization can be significantly enhanced by optimization of the sublimation temperature. The rate of argon flow is seen to have little influence on either the saturation magnetization or the coercivity. Furthermore, the study of remnant magnetization as a function of time revealed that magnetization decay rates can be considerably varied.