Quantum Interference in Carbon-Nanotube Electron Resonators

A new mechanism is proposed to explain the slow conductance fluctuations in the conductance-gate voltage plot observed in the nanotube electron resonators. It is found that the slow conductance fluctuation is an intrinsic quantum interference phenomenon and exists in all metallic nanotube resonators except zigzag ones. Analytical expressions for both slow and rapid oscillation periods of the conductance fluctuations have been derived, which are well consistent with the existing experiments. It is predicted that the ratio of the slow oscillation period to the rapid one is independent of the gate-voltage efficiency, and determined only by the nanotube length used in experiments.

Figure 1

A theoretical model of an armchair nanotube electron resonator. The atoms on a highlighted ring construct an interface. (a) and (b) are schematic three-dimensional and two-dimensional pictures, respectively. The electron trajectories for an electron injected from a channel are illustrated in (c).

Figure 2

Zero-bias conductance vs gate voltage of an armchair nanotube device with $\alpha =0.01$, $u_1=1.0\mathrm{e}\mathrm{V}$, $u_2=6.0\mathrm{e}\mathrm{V}$, and $M=1624$ rings of atoms. Inset, a plot in a narrower energy region near $V_g=0$.