Symmetries and the conductance of graphene nanoribbons with long-range disorder

Jürgen Wurm, Michael Wimmer, and Klaus Richter
Phys. Rev. B 85, 245418 – Published 8 June 2012

Abstract

We study the conductance of graphene nanoribbons with long-range disorder. Due to the absence of intervalley scattering from the disorder potential, time-reversal symmetry (TRS) can be effectively broken even without a magnetic field, depending on the type of ribbon edge. Even though armchair edges generally mix valleys, we show that metallic armchair nanoribbons possess a hidden pseudovalley structure and an effectively broken TRS. In contrast, semiconducting armchair nanoribbons inevitably mix valleys and restore TRS. As a result, in strong disorder metallic armchair ribbons exhibit a perfectly conducting channel, but semiconducting armchair ribbons exhibit ordinary localization. TRS is also effectively broken in zigzag nanoribbons in the absence of valley mixing. However, we show that intervalley scattering in zigzag ribbons is significantly enhanced and TRS is restored even for smooth disorder if the Fermi energy is smaller than the potential amplitude. The symmetry properties of disordered nanoribbons are also reflected in their conductance in the diffusive regime. In particular, we find suppression of weak localization and an enhancement of conductance fluctuations in metallic armchair and zigzag ribbons without valley mixing. In contrast, semiconducting armchair and zigzag ribbons with valley mixing exhibit weak localization behavior.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
2 More
  • Received 25 November 2011

DOI:https://doi.org/10.1103/PhysRevB.85.245418

©2012 American Physical Society

Authors & Affiliations

Jürgen Wurm1, Michael Wimmer2, and Klaus Richter1

  • 1Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
  • 2Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 85, Iss. 24 — 15 June 2012

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×