Effects of band structure and quantum interference on the differential conductance of infinite metallic single-wall carbon nanotubes

Abstract

Using a π-orbital tight-binding (TB) model within a perturbative formalism, the effects of substitutional impurities on the conductance of infinite metallic single-wall carbon nanotubes (MSWCNTs) are studied. The perturbative scheme is based on the energy dissipation of electrons travelling through the nanotube. A general expression for the differential conductance (DC) is presented, and scattering processes are investigated. It is demonstrated how the DC depends sensitively on the nature of the electronic band structure and velocity of carriers moving in the nanotube. We have shown that the quantum interference (QI) of electronic waves scattered by impurities plays a meaningful role. In particular, for the case of a couple of impurities the DC exhibits periodic oscillations comprising both positive and negative values. The negative differential conductance (NDC) stemming from the QI and rotational symmetry selection rule is very sensitive to the relative distance and symmetry of two impurities. This signature is absent for the case of a single impurity. In fact, the NDC can be attributed to the zero-temperature/elastic weak-localization correction to the conductance. As a result, the faster/higher and slower/shorter oscillations can then effectively be achieved by metallic zigzag and armchair nanotubes, respectively. A corrigendum for this article has been published in 2007 J. Phys.: Condens. Matter 19 469001

Effect of electron-RBM phonon interaction on conductance of metallic zigzag carbon nanotubes

“…Now consider a bias voltage eV << E F , where E F is the Fermi energy of electrons in the nanotube, applied on the mesoscopic structure including a metallic zigzag SWCNT, which its length is much larger than its diameter and it is connected to metallic reservoirs. It is assumed that the length of two metallic electrodes is in the order of λ F , hence, the transportation of ballistic electrons through the nanotube is robust against the edge effect 42,43 . In addition, the rate reduction of the electric field in the nanotube is proportional to a/L (where 1.25 < a < 1.75 Å) and L is the nanotube length 44 .…”

Aharonov–Bohm differential conductance modulation in defective metallic single-walled carbon nanotubes

“…In the presence of an uniform magnetic field B parallel to the nanotube axis, the wrapping modes are modified according to q/r t → q/r t + Φ ρ /r t [31], so the magnetic field dependent band-structure E ± q+Φρ (k) is [44] E ± q+Φρ (k)…”

“…Further, for later calculations, we have exploited the corresponding Bloch's states of an isolated nanotube previously derived in Ref. [44].…”

“…The full descriptions of the model in the absence of the magnetic field can be found in Ref. [44]. Here, we just add the AB-flux in its band-structure, so the Hamiltonian of the whole system is given by…”

“…In the above equation the first term, describing the kinetic energy of electrons for a perfect nanotube, is given by [44,46] Ĥtube…”