Finite-size version of the excitonic instability in graphene quantum dots

Journal Article · Sat Oct 15 00:00:00 EDT 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.84.155456· OSTI ID:21596905

Paananen, Tomi; Egger, Reinhold ^[1]

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1. Institut fuer Theoretische Physik, Heinrich-Heine-Universitaet, D-40225 Duesseldorf (Germany)

By a combination of Hartree-Fock simulations, exact diagonalization, and perturbative calculations, we investigate the ground-state properties of disorder-free circular quantum dots formed in a graphene monolayer. Taking the reference chemical potential at the Dirac point, we study N{<=}15 interacting particles, where the fine structure constant {alpha} parametrizes the Coulomb interaction. We explore three different models: (i) Sucher's positive projection (''no-pair'') approach, (ii) a more general Hamiltonian conserving both N and the number of additional electron-hole pairs, and (iii) the full quantum electrodynamics problem, where only N is conserved. We find that electron-hole pair production is important for {alpha} > or approx. 1. This corresponds to a reconstruction of the filled Dirac sea and is a finite-size version of the bulk excitonic instability. We also address the effects of an orbital magnetic field.

• OSTI ID: 21596905
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 15; Other Information: DOI: 10.1103/PhysRevB.84.155456; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON
FINE STRUCTURE
GROUND STATES
HAMILTONIANS
HARTREE-FOCK METHOD
HONEYCOMB STRUCTURES
INSTABILITY
MAGNETIC FIELDS
PAIR PRODUCTION
PERTURBATION THEORY
QUANTUM DOTS
QUANTUM ELECTRODYNAMICS
SIMULATION
APPROXIMATIONS
CALCULATION METHODS
ELECTRODYNAMICS
ELEMENTS
ENERGY LEVELS
FIELD THEORIES
INTERACTIONS
MATHEMATICAL OPERATORS
MECHANICAL STRUCTURES
NANOSTRUCTURES
NONMETALS
PARTICLE PRODUCTION
QUANTUM FIELD THEORY
QUANTUM OPERATORS