Selective Excitations of Transverse Vibrational Modes of a Carbon Nanotube through a “Shuttle-Like” Electromechanical Instability

Figure 1

Sketch of the model system considered. A metallic carbon nanotube is suspended over the trench between two metallic leads which are mantained at the same electrochemical potential, while an STM is put at distance $d$ above the point $z_0$ along the nanotube axis. A bias voltage $V_b$ is applied between the STM tip and the supporting leads, so that electrons can tunnel to and from the suspended carbon nanotube. The distance between the nanotube and the STM tip affects the electron tunneling rate between them, while the tunneling rate between the nanotube and the leads is constant (the vibration amplitude and the STM-nanotube equilibrium distance $d$ shown are exaggerated for clarity).