Persistent currents in a graphene ring with armchair edges

Abstract

A graphene nano-ribbon with armchair edges is known to have no edge state. However, if the nano-ribbon is in the quantum spin Hall (QSH) state, then there must be helical edge states. By folding a graphene ribbon to a ring and threading it by a magnetic flux, we study the persistent charge and spin currents in the tight-binding limit. It is found that, for a broad ribbon, the edge spin current approaches a finite value independent of the radius of the ring. For a narrow ribbon, inter-edge coupling between the edge states could open the Dirac gap and reduce the overall persistent currents. Furthermore, by enhancing the Rashba coupling, we find that the persistent spin current gradually reduces to zero at a critical value, beyond which the graphene is no longer a QSH insulator.

References in corpus (6)

• Energy Gaps in Graphene Nanoribbons
• Intrinsic and Rashba Spin-orbit Interactions in Graphene Sheets
• Aharonov-Bohm effect and broken valley-degeneracy in graphene rings
• Aharonov-Bohm oscillations in disordered topological insulator nanowires
• Anomalous Aharonov-Bohm conductance oscillations from topological insulator surface states
• Persistent currents in a graphene ring with armchair edges

Cited by in corpus (6)

• Persistent currents in a graphene ring with armchair edges
• Localized electron states near the armchair edge of graphene
• Effect of magnetic field on the electronic properties of an $\alpha$-$T_3$ ring
• Relativistic fermion on a ring: Energy spectrum and persistent current
• Electronic Properties of Graphene Quantum Ring with Wedge Disclination
• Persistent current-carrying state of charge quasuparticles in $np$-ribbon featuring single Dirac cone