Magnetic field induced localization in carbon nanotubes

TL;DR

Applying a magnetic field along the axis of carbon nanotubes causes extended electronic states to gradually localize at the ends, ultimately suppressing transport when a threshold field is exceeded, depending on nanotube properties.

Contribution

This study demonstrates how magnetic fields induce localization of electronic states in carbon nanotubes, revealing a controllable mechanism for transport suppression.

Findings

Magnetic field modifies momentum quantization in CNTs.

States become localized at the ends with increasing magnetic field.

Transport is suppressed beyond a certain magnetic field threshold.

Abstract

The electronic spectra of long carbon nanotubes (CNTs) can, to a very good approximation, be obtained using the dispersion relation of graphene with both angular and axial periodic boundary conditions. In short CNTs one must account for the presence of open ends, which may give rise to states localized at the edges. We show that when a magnetic field is applied parallel to the tube axis, it modifies both momentum quantization conditions, causing hitherto extended states to localize near the ends. This localization is gradual and initially the involved states are still conducting. Beyond a threshold value of the magnetic field, which depends on the nanotube chirality and length, the localization is complete and the transport is suppressed.