2007/06/30 by P. Recher, Patrik Recher, B. Trauzettel +7 · 15 citations
Chemistry · Materials Science · Physics and Astronomy · #Antiferromagnetism #Chemistry #Condensed matter physics #Degeneracy (biology) #Geometry #Graphene #Graphene research and applications #Hexagonal lattice #Lattice (music) #Magnetic field #Magnetic flux #Observable #Physics #Quantum and electron transport phenomena #Quantum mechanics #Ring (chemistry) #Scattering #Topological Materials and Phenomena #Zigzag #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.76.235404
published as Phys. Rev. B 76, 235404 (2007) · 7 pages, 7 figures, replaced with considerably extended new version
arxiv created 2007/09/28 · openalex publication_date 2007/12/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We analyze theoretically the electronic properties of Aharonov-Bohm rings made of graphene. We show that the combined effect of the ring confinement and applied magnetic flux offers a controllable way to lift the orbital degeneracy originating from the two valleys, even in the absence of intervalley scattering. The phenomenon has observable consequences on the persistent current circulating around the closed graphene ring, as well as on the ring conductance. We explicitly confirm this prediction analytically for a circular ring with a smooth boundary modeled by a space-dependent mass term in the Dirac equation. This model describes rings with zero or weak intervalley scattering so that the valley isospin is a good quantum number. The tunable breaking of the valley degeneracy by the flux allows for the controlled manipulation of valley isospins. We compare our analytical model to another type of ring with strong intervalley scattering. For the latter case, we study a ring of hexagonal form with lattice-terminated zigzag edges numerically. We find for the hexagonal ring that the orbital degeneracy can still be controlled via the flux, similar to the ring with the mass confinement.