Theoretical Analysis of AC Transport in Carbon Nanotubes with a Single Atomic Vacancy: Sharp Contrast between DC and AC Responses in Vacancy Position Dependence

Abstract

AC transport properties of metallic carbon nanotubes with a single atomic vacancy are investigated using the Keldysh nonequilibrium Green's function method. We found that the susceptance does depend on the position of the vacancy, which makes a strong contrast to the positionindependence of the DC conductance. In addition, the susceptance indicates an inductive response in spite of the small DC conductance, when the distance between the center of the nanotube and the vacancy is larger than a certain threshold. The position dependence of the susceptance can be understood as a consequence of the breaking of parity symmetry. #

Anomalous satellite inductive peaks in alternating current response of defective carbon nanotubes

“…7,8 The correlation between low-frequency admittance and DC conductance is well-known in other systems. [9][10][11][12] Very recently, based on nonequilibrium Green's function (NEGF) method and tight-binding approximation, we examined the influence of a single atomic vacancy on the AC response and clarified that electron scattering by the vacancy state around the Fermi level induces capacitive response 13,14 in contrast to pristine metallic CNTs which behave inductively.…”

Alternating current response of carbon nanotubes with randomly distributed impurities

“…In our previous studies, [16][17][18] we have clarified that electron scattering induces a capacitive response. Here, it should be noted that the electron scattering in these cases involves a decrease in the DC conductance, which is in sharp contrast with the present case of long-range impurity scattering.…”

“…10,11 In addition, we have also examined the influence of a single defect on the AC response, which strongly decreases the DC conductance, [12][13][14][15] and we have clarified that electron scattering by the defect state induces a capacitive response. [16][17][18] The effects of the kinetic inductance and electron backscattering on the AC response have been studied and understood for the above simple cases. However, it is unclear whether the findings obtained from such simple systems are sufficient to understand real systems, which are more complicated.…”

“…This suggests that there is a competition between two dominant factors that determine the emittance behaviors: the kinetic inductance, which contributes to the inductive response 4,6,8,9,18 and is proportional to the transport time of electrons, and the electron scattering, which leads to the capacitive response. [16][17][18] Based on this fact, we can understand the emittance responses as follows. When the CNT length is small (<200 nm), the effect of electron scattering is weak as can be observed in the DC conductance behaviors.…”

“…From these results, we can conclude that the AC transport behaviors for short-range impurity scattering can be understood in a manner similar to the cases of simpler systems examined in our previous investigations. 4,[16][17][18] We next examine the effect of long-range impurity scattering on the AC response. Figure 1(b) shows the AC response of (10,10) metallic CNTs with randomly distributed long-range impurity potentials.…”