Metal-Semiconductor Transition and Fermi Velocity Renormalization in Metallic Carbon Nanotubes

Abstract

Angular perturbations modify the band structure of armchair (and other metallic) carbon nanotubes by breaking the tube symmetry and may induce a metal-semiconductor transition when certain selection rules are satisfied. The symmetry requirements apply for both the nanotube and the perturbation potential, as studied within a nonorthogonal $\pi$-orbital tight-binding method. Perturbations of two categories are considered: an on-site electrostatic potential and a lattice deformation which changes the off-site hopping integrals. Armchair nanotubes are proved to be robust against the metal-semiconductor transition in second-order perturbation theory due to their high symmetry, but can develop a nonzero gap by extending the perturbation series to higher orders or by combining potentials of different types. An assumption of orthogonality between $\pi$ orbitals is shown to lead to an accidental electron-hole symmetry and extra selection rules that are weakly broken in the nonorthogonal theory. These results are further generalized to metallic nanotubes of arbitrary chirality.

Submitted to Phys. Rev. B, 23 pages, 4 figures

References in corpus (8)

• Tuning carbon nanotube bandgaps with strain
• Metal-to-semiconductor transition in squashed armchair carbon nanotubes
• Electronic response and bandstructure modulation of carbon nanotubes in a transverse electrical field
• Reversible Band Gap Engineering in Carbon Nanotubes by Radial Deformation
• Possibility of a Metallic Field-Effect Transistor
• Analysis of band-gap formation in squashed arm-chair CNT
• Locally addressable tunnel barriers within a carbon nanotube
• Metal-Semiconductor Transition in Armchair Carbon Nanotubes by Symmetry Breaking

Cited by in corpus (1)

• Terahertz emitters and detectors based on carbon nanotubes