Electrical evidence for the encapsulation of C$_{60}$ inside a carbon nanotube: Random telegraph signal and hysteric current-voltage characteristics

We present electrical evidence for the encapsulation of C$_{60}$'s inside a carbon nanotube: random telegraph signals (RTSs), and hysteric current-voltage characteristics. The RTSs is ascribed to the instability of the quantum harmonic oscillations of C$_{60}$'s. RTSs are smeared out at a temperature which is consistent with the energy level of the vibrational quantum mediated by the van der Waals binding between the carbon nanotube and C$_{60}$'s. In addition, hysteric behavior in cyclic current-voltage characteristics is explained by the longitudinal motion and resettlement of the C$_{60}$'s with the modulation of the size of the quantum dot mediated by the C$_{60}$ insertion.