Persistent charge and spin currents in the long wavelength regime for graphene rings

Abstract

We address the problem of persistent charge and spin currents on a Corbino disk built from a graphene sheet. We consistently derive the Hamiltonian including kinetic, intrinsic (ISO) and Rashba spin-orbit interactions in cylindrical coordinates. The Hamiltonian is carefully considered to reflect hermiticity and covariance. We compute the energy spectrum and the corresponding eigenfunctions separately for the intrinsic and Rashba spin-orbit interactions. In order to determine the charge persistent currents we use the spectrum equilibrium linear response definition. We also determine the spin and pseudo spin polarizations associated with such equilibrium currents. For the intrinsic case one can also compute the correct currents by applying the bare velocity operator to the ISO wavefunctions or alternatively the ISO group velocity operator to the free wavefunctions. Charge currents for both SO couplings are maximal in the vicinity of half integer flux quanta. Such maximal currents are protected from thermal effects because contributing levels plunge ($\sim$1K) into the Fermi sea at half integer flux values. Such a mechanism, makes them observable at readily accessible temperatures. Spin currents only arise for the Rashba coupling, due to the spin symmetry of the ISO spectrum. For the Rashba coupling, spin currents are cancelled at half integer fluxes but they remain finite in the vicinity, and the same scenario above protects spin currents.

References in corpus (11)

• The electronic properties of graphene
• Electronic States of Graphene Nanoribbons
• Intrinsic and Rashba Spin-orbit Interactions in Graphene Sheets
• Spin-orbit coupling in curved graphene, fullerenes, nanotubes, and nanotube caps
• Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes
• Magnetic confinement of massless Dirac fermions in graphene
• Aharonov-Bohm effect and broken valley-degeneracy in graphene rings
• Currents and pseudomagnetic fields in strained graphene rings
• Antiferromagnetism in hexagonal graphene structures: Rings vs dots
• Engineering Quantum Spin Hall Effect in Graphene Nanoribbons via Edge Functionalization
• Spin superfluidity and spin-orbit gauge symmetry fixing

Cited by in corpus (12)

• Proximity induced spin orbit effects in graphene on Au
• Topological and noninertial effects in an Aharonov-Bohm ring
• Quantum oscillation and wave packet revival in conical graphene structure
• Spin-orbit induced equilibrium spin currents in materials
• Ferromagnetic order induced on graphene by Ni/Co proximity effects
• Charge and spin polarized currents in mesoscopic rings with Rashba spin-orbit interactions coupled to an electron reservoir
• Equilibrium currents in a Corbino graphene ring
• Effect of magnetic field on the electronic properties of an $\alpha$-$T_3$ ring
• Dirac electrons in quantum rings
• Robustness of persistent currents in two-dimensional Dirac systems with disorders
• Topologically protected wave packets and quantum rings in silicene
• Persistent currents in topological and trivial confinement in silicene